The HVAC job market is tight enough that most shops are actively recruiting — but that doesn't mean every candidate gets hired. Service managers still cut plenty of people loose after the first conversation, and it's almost never because the person couldn't wire a contactor. It's because they fumbled basic technical questions, gave vague answers about past callbacks, or showed zero curiosity about how the company actually operates.
This guide covers 40 questions that come up consistently in HVAC interviews, organized by category. For each one, you'll get a clear picture of what the interviewer is really evaluating and how to frame a strong response. Not scripts — frameworks. The actual words should come from your experience.
Before you start reading, pull up current openings on HVACJobs.IO and identify two or three positions you're genuinely interested in. The best interview prep is knowing the specific company you're walking into.
How HVAC Interviews Actually Work
The format depends heavily on company size.
At a small shop — owner-operated, 3 to 15 techs — the interview is usually one conversation with the owner or service manager, often in the shop or a back office. It's informal. The owner might walk you to a piece of equipment and ask you to talk through what you'd check. These conversations go deep fast. Owners don't waste time on HR screening questions; they want to know if you can do the work without hand-holding.
At a mid-to-large company — regional or national service organizations, large mechanical contractors — expect two or three rounds. First is an HR phone screen (15-30 minutes, mostly soft skills and schedule availability). Second is a technical interview, often with the service manager or a lead tech. Some companies add a hands-on skills assessment. The questions are more structured and they're often comparing you against other candidates on a scoring rubric.
Know which environment you're walking into. The preparation is different.
Section 1: Technical Knowledge (Questions 1-14)
These are the questions that eliminate the most candidates. Interviewers aren't looking for textbook recitation — they're looking for applied understanding. There's a difference between someone who memorized what superheat means and someone who has actually adjusted charge based on it.
1. Walk me through the refrigeration cycle.
What they're evaluating: Whether you have a solid mental model of how the system works, not just the steps memorized. A weak candidate rattles off "compressor, condenser, expansion valve, evaporator" and stops there. A strong candidate explains what's happening to the refrigerant at each stage — the state change, the pressure change, and why it matters.
How to answer: Start at the compressor. Explain that the refrigerant enters as a low-pressure vapor, gets compressed to a high-pressure vapor, then moves to the condenser where it rejects heat to the outdoor air and becomes a high-pressure liquid. From there, the metering device drops the pressure and temperature before the refrigerant enters the evaporator, where it absorbs heat from the indoor air and boils back to a vapor before returning to the compressor. If you want to impress, mention the relationship between pressure and saturation temperature.
2. What's the difference between superheat and subcooling, and what do your readings tell you?
What they're evaluating: This is the single most common technical question in HVAC interviews, and it eliminates a surprising number of candidates. Interviewers want to know you can use these measurements diagnostically, not just define the terms.
How to answer: Superheat is the temperature of the refrigerant vapor above its saturation point, measured at the suction line. It tells you the refrigerant has fully boiled before it hits the compressor — liquid refrigerant reaching the compressor is a fast way to destroy it. Target superheat on a TXV system is typically 8-12°F at the evaporator. Subcooling is the temperature of the liquid refrigerant below its condensing point, measured at the liquid line leaving the condenser. It confirms you have a solid column of liquid reaching the metering device. Target subcooling on most residential equipment is 10-15°F. Too little superheat suggests overcharge or metering device issues; too little subcooling often points to undercharge or a restricted liquid line.
3. A customer calls and says their system is running but not cooling. Walk me through your diagnostic process.
What they're evaluating: Systematic thinking. Interviewers have seen too many techs who swap parts hoping to get lucky. They want to see a methodical approach that narrows down the failure point before touching anything.
How to answer: Start with the simple stuff — confirm the thermostat is set correctly and the filter isn't blocked. Then check if both the air handler and condenser are running. Measure supply and return air temperatures; if delta-T is low, that points you toward the refrigerant circuit. Pull out the gauges: suction and discharge pressure will tell you a lot. Measure superheat and subcooling. Check static pressure if you suspect an airflow issue. The point is to develop a theory before you start replacing components, not after.
4. What causes a compressor to fail, and how do you diagnose one?
What they're evaluating: Depth of experience. This question separates techs who fix symptoms from techs who identify root causes.
How to answer: Common causes include liquid slugging (refrigerant or oil returning to the compressor), low voltage, overheating due to poor airflow or high ambient, loss of lubrication, and running on two legs of power. To diagnose a failed compressor, check voltage at the terminals first — many apparent compressor failures are actually capacitor failures or low-voltage problems. Measure amp draw and compare to the nameplate RLA. Check winding resistance with an ohmmeter and megohm test to ground if you suspect a grounded winding. A compressor that trips on thermal overload repeatedly has an underlying issue that needs to be found before you replace it.
5. Explain the difference between a TXV and a fixed orifice metering device. When would you see each?
What they're evaluating: Whether you understand how different metering devices behave and what that means for diagnosis.
How to answer: A fixed orifice (piston or orifice plate) is passive — it doesn't adjust to load changes. It's common on lower-cost residential equipment and simpler applications. A TXV (thermostatic expansion valve) modulates based on suction line superheat, maintaining a more consistent superheat across varying load conditions. TXVs are more common on commercial equipment and higher-efficiency residential systems. The diagnostic difference matters: on a fixed orifice system, charge is critical because there's no compensation for under or overcharge. On a TXV system, if superheat is way off, you check the valve before assuming the charge is wrong.
6. How do you verify a proper system evacuation?
What they're evaluating: Whether you actually pull a proper vacuum or just pull it down quickly and move on.
How to answer: The right answer here involves a micron gauge, not just a manifold gauge. Pull the system down to 500 microns or lower. Then isolate the system from the vacuum pump and watch the micron gauge. If the reading rises quickly and stabilizes at a high number, you have a leak or residual moisture. If it rises slowly and stabilizes around 1,000-1,500 microns, you're seeing refrigerant boiling off and should keep pulling. You're done when the reading holds below 500 microns after isolation. A lot of shops skip the micron gauge — that's a problem.
7. You're looking at a wiring diagram for a unit you've never seen before. How do you approach it?
What they're evaluating: Whether you're comfortable with electrical work on unfamiliar equipment, which you'll deal with constantly.
How to answer: Start by identifying the power supply — single-phase or three-phase, what voltage. Find the control transformer (usually 24V secondary). Trace the thermostat circuit and understand what each call — Y, W, G, O/B — does in that system. Follow the load circuits: what controls each output, and what safety devices (pressure switches, high limits, float switches) are in series. Most equipment follows similar logic even if the layout differs. The legend and component locator on the diagram are your friends.
8. What refrigerants have you worked with, and what's your understanding of the R-410A phaseout?
What they're evaluating: Current awareness of the industry transition. This is increasingly important given the 2025 regulatory changes.
How to answer: You should know that R-22 has been fully phased out — it's no longer produced or imported in the US. R-410A is in the process of being phased out under the AIM Act and EPA Section 608 updates, with new residential and light commercial equipment required to use lower-GWP refrigerants starting in 2025. The likely replacement in most residential equipment is R-454B (sold as Puron Advance by Carrier, and as other trade names by different manufacturers). R-454B is an A2L refrigerant — mildly flammable — which means installation and service procedures are different. Leak detection requirements, brazing protocols, and ventilation requirements change with A2L refrigerants. If you haven't done A2L training yet, say so honestly and mention you're planning to get it.
9. Walk me through how you'd check for refrigerant leaks on a commercial rooftop unit.
What they're evaluating: Systematic leak search technique and familiarity with commercial equipment.
How to answer: Start where leaks are most common — brazed fittings, flare connections, service valves, and anywhere vibration is present (compressor discharge, fan motor mounting areas). Use an electronic leak detector as your primary tool, working from the bottom of the coil up since most refrigerants are heavier than air. Follow any positive readings with UV dye detection if the system has been previously charged with dye. Mark the leak location, verify the leak rate with soapy solution or electronic detector confirmation, repair it, pressure test the repair, re-evacuate the affected section, and recharge. Document the leak location and repair in your service ticket.
10. How do you approach a no-heat call on a gas furnace?
What they're evaluating: Furnace diagnostic process and understanding of ignition sequences.
How to answer: Watch the furnace go through its ignition sequence before touching anything — most modern furnaces will tell you what's wrong through LED fault codes. Confirm gas pressure at the manifold (typically 3.5" WC for natural gas on most residential equipment). Check the igniter: hot surface igniters fail frequently and can be cracked without being visually obvious — measure resistance. Verify the flame sensor is clean; a coated flame sensor causes intermittent lockouts. Check for proper airflow — a clogged filter or restricted return can trip the limit switch. If the heat exchanger is questionable, run a CO test and combustion analysis.
11. What's your process for commissioning a new split system after installation?
What they're evaluating: Attention to detail and whether you follow a real startup procedure or just turn it on and leave.
How to answer: Verify refrigerant line connections are tight, the system has been properly evacuated, and the charge is correct for the line set length (most manufacturers have a charging chart for line set adjustments). Verify electrical connections at both the air handler and condenser — check voltage at the unit, not just the breaker. Confirm control wiring is correct and the thermostat is programmed. Let the system run, verify delta-T across the coil, pull superheat and subcooling readings, and check static pressure if you have access. Check for any installation defects before the customer sees the system running. Fill out and leave the startup documentation.
12. Explain how a heat pump operates in heating mode.
What they're evaluating: Whether you understand the refrigerant cycle runs in reverse in heating mode and can explain the reversing valve.
How to answer: In heating mode, the refrigerant circuit is reversed compared to cooling. The outdoor coil becomes the evaporator — it absorbs heat from the outdoor air even when temperatures are low. The indoor coil becomes the condenser, rejecting that heat to the indoor air. The reversing valve (energized in cooling on most manufacturers, de-energized in heating) switches the refrigerant flow path. Defrost mode matters here too: when the outdoor coil ices up, the system temporarily reverses back to cooling mode to melt the ice, which is why the system might briefly blow cool air inside during defrost and the auxiliary heat may come on.
13. What's your approach to a system that trips on high-pressure lockout?
What they're evaluating: Whether you look for the cause or just reset the switch and leave.
How to answer: High-pressure lockout means the discharge pressure exceeded the high-pressure switch cutout. Before resetting anything, figure out why. Common causes: dirty condenser coil, failed condenser fan motor or blade, blocked airflow around the outdoor unit, refrigerant overcharge, non-condensable gases in the system, or a failed high-pressure switch. Check the condenser coil and fan operation first since those are the most common culprits. Measure discharge pressure while the unit runs — if it's riding high even with good airflow, check for overcharge or non-condensables. Never just reset a safety switch and walk away.
14. How do you handle refrigerant recovery, and what does proper recovery documentation look like?
What they're evaluating: Legal compliance knowledge and professionalism. Also relevant for the EPA question that will likely come up in Section 3.
How to answer: Recovery is required by law before opening any refrigerant circuit — you cannot vent refrigerant intentionally. Use a recovery machine rated for the refrigerant type, with a recovery cylinder that's been verified to be within its hydrostatic test date and not overfilled. Know the required recovery levels under EPA 608: for systems with compressors 200 BTU/hr or greater, you need to recover to specified vacuum levels depending on the system type and the year the recovery equipment was manufactured. Keep a service log documenting the amount of refrigerant recovered, added, and the cylinder number. Proper records protect you legally and are required for systems over 50 lbs refrigerant charge.
Section 2: Experience and Skills (Questions 15-24)
These questions are about pattern recognition — interviewers want to know how you behave in real situations, not how you'd theoretically handle them.
15. Tell me about the most difficult diagnostic you've ever faced. What made it hard, and how did you figure it out?
What they're evaluating: Critical thinking under pressure and intellectual honesty. They're also listening to see if you take personal credit for figuring things out or if you credit your team or reference materials appropriately.
How to answer: Pick a real story — not your most dramatic, but one that shows a logical process. Set up the situation briefly, explain what made it hard (intermittent fault, conflicting symptoms, unusual equipment), and walk through your diagnostic steps. Don't skip the part where you were wrong about something and had to reconsider. That's the part that shows you're honest and adaptable.
16. What tools do you carry on your service truck?
What they're evaluating: Whether your toolset matches the type of work they do. A residential tech with a well-stocked truck for residential work may look light for commercial. They're also evaluating whether you invest in your own tools or expect the company to provide everything.
How to answer: Cover the core categories: manifold gauges (and whether they're digital or traditional), micron gauge, refrigerant scale, multimeter (mention the brand — Fluke is the industry standard and signals you're serious), clamp meter, combustion analyzer if you do gas work, a good set of wrenches and hex keys, core tools, brazing equipment if you're field brazing, and any specialty tools relevant to what you do. If there are gaps, be upfront about it rather than exaggerating.
17. What types of HVAC systems have you worked on? What's your strongest area?
What they're evaluating: Fit for the specific role. A company that does high-rise commercial work doesn't want a tech whose entire background is residential split systems, and vice versa.
How to answer: Be specific. "Residential" is too broad — say residential split systems, heat pumps, packaged units, mini-splits. For commercial, name the specific equipment types: RTUs, chillers, fan coil units, VAV systems, DDC controls. Name the brands you've worked on extensively. Then directly answer what your strongest area is and why — employers appreciate honesty about what you know well versus where you're still developing.
18. How do you handle a callback? What's your approach when a repair you did didn't fix the problem?
What they're evaluating: Professional accountability. This question separates mature techs from defensive ones. The defensive answer blames the equipment, the customer, or bad luck. The mature answer takes ownership.
How to answer: Say you go back the same day whenever possible. Explain that your first step is to actually listen to the customer — they may have observed something that changes the diagnosis. Then re-approach the system fresh, considering whether your initial diagnosis was wrong or whether there's a secondary problem you missed. Be honest that callbacks are part of the job and that how you handle them affects the company's reputation.
19. Describe your experience with building automation systems or commercial controls.
What they're evaluating: Whether you can navigate DDC (Direct Digital Control) systems, BACnet, or proprietary building automation platforms, which matter significantly for commercial and industrial work.
How to answer: Name the specific platforms you've worked with — Johnson Controls Metasys, Siemens Desigo, Honeywell Niagara/WebCT, Automated Logic, Tridium, or others. Be honest about your depth of experience: there's a difference between navigating an existing BAS to read sensor data and actually programming sequences of operation. If your controls experience is limited, say so and mention your interest in developing that skill.
20. How do you stay current with new equipment and technology?
What they're evaluating: Whether you're self-directed about learning or wait to be trained. The HVAC industry is changing fast enough that passive techs fall behind.
How to answer: Name specific resources you actually use — manufacturer training (Carrier University, Lennox Learning Solutions, Trane TechUniversity, Daikin Training), trade publications, ACCA membership, online communities, YouTube channels from actual HVAC professionals. If you're working toward NATE certification or additional specialty certifications, mention it. Interviewers at good companies know the difference between techs who invest in themselves and techs who don't.
21. What's the largest or most complex system you've personally worked on?
What they're evaluating: Whether your experience scale matches their work. They also want to see if you can talk intelligently about complex equipment.
How to answer: Give specific numbers where you can — tonnage, the type of equipment, the scope of work you personally performed versus supervised. If you've worked on chillers, VRF systems, or large commercial equipment, describe the specifics. If your experience has been primarily residential, own that and explain what makes you confident you can scale up.
22. Tell me about a time you caught something that prevented a major failure or safety issue.
What they're evaluating: Thoroughness and safety awareness. They want techs who find problems before they become emergencies, not techs who do the minimum and leave.
How to answer: A good answer here involves noticing something beyond the original scope of the service call — a cracked heat exchanger discovered on a maintenance visit, a corroded electrical connection that would have failed in a few weeks, a refrigerant leak that was just starting. Describe what you noticed, what you did about it, and how you communicated it to the customer or your manager.
23. How do you handle multiple service calls in a day when you're running behind?
What they're evaluating: Time management and communication skills. Bad techs silently fall behind and surprise everyone at 6 PM. Good techs communicate proactively.
How to answer: Explain that you communicate early — if you can tell at 10 AM that you're going to be behind, you call dispatch then, not at 3 PM. Triage matters: a no-heat call in January outranks a maintenance visit. Be honest about what you can and can't get done in a day rather than overpromising and underdelivering.
24. What NATE certifications do you hold, or are you working toward?
What they're evaluating: Professional credentialing. NATE certification is the most widely recognized third-party credential in the HVAC industry. Many employers pay a premium for NATE-certified techs.
How to answer: List any NATE specialty certifications you hold — Air Conditioning, Heat Pumps, Gas Heating, Air Distribution, etc. If you don't have any yet, be honest and explain whether and when you plan to pursue them. Employers who pay for continuing education will want to know you're committed to it.
Section 3: Safety and Compliance (Questions 25-31)
Safety questions aren't just about protecting the company from liability — they're about making sure you're not going to hurt yourself, your coworkers, or a customer.
25. What does your EPA 608 certification cover, and what are the legal requirements for refrigerant handling?
What they're evaluating: Whether you actually know the regulations, not just that you have a card.
How to answer: EPA Section 608 certification is legally required for any technician who purchases, handles, or recovers refrigerants covered by the Clean Air Act. The four types are Type I (small appliances), Type II (high- and very high-pressure equipment), Type III (low-pressure equipment), and Universal. The Universal certification covers all equipment types and is what most working techs carry. The law prohibits intentional venting of refrigerants, requires recovery before opening any system, and has specific recovery level requirements based on system size and compressor capacity. As of 2025, EPA is also rolling out updated regulations under the AIM Act covering newer A2L refrigerants.
26. Walk me through your lockout/tagout procedure before servicing a condenser.
What they're evaluating: Whether you actually follow LOTO or whether you just say you do.
How to answer: Notify affected personnel before starting. Turn off the thermostat or disconnect control power to prevent the system from being called on. Go to the electrical disconnect or breaker and shut off power to the unit. Lock it out with your personal lock — not a shared lock. Tag it with your name and contact information. Verify de-energization with your meter at the unit's terminals before touching any components. If the unit has capacitors, discharge them before working on the electrical panel. For three-phase commercial equipment, verify all three legs are dead. Do not remove your lock until you are done and clear of the equipment.
27. What are the signs of a cracked heat exchanger, and what do you do when you find one?
What they're evaluating: Carbon monoxide safety awareness and professional response to a serious finding.
How to answer: Signs include visible cracks on inspection, rust streaking from the heat exchanger into the blower area, combustion odors in the supply air, or elevated CO readings in the living space. A combustion analyzer will show elevated CO in the flue gases. Some techs use the flame deflection test — watch for flame movement when the blower comes on, which indicates air from the heat exchanger side affecting combustion. When you find a cracked heat exchanger, you red-tag the unit, shut off the gas supply, and document your finding in the service record. You don't just recommend replacement — you shut it down. That's non-negotiable.
28. Have you ever worked in a confined space? What are the requirements?
What they're evaluating: Whether you've had formal confined space training and understand the distinction between permit-required and non-permit spaces.
How to answer: OSHA's confined space standard (29 CFR 1910.146) defines confined spaces as areas large enough to enter, with limited entry/exit, and not designed for continuous occupancy. A permit-required confined space additionally has one of the following: contains or could contain a hazardous atmosphere, has material that could engulf the entrant, has internal configuration that could trap a person, or contains any other serious safety hazard. Permit-required spaces require atmospheric testing before entry, continuous monitoring, a trained attendant, a rescue plan, and written permits. Mechanical rooms with refrigerant equipment can qualify as permit spaces depending on the refrigerant charge and ventilation. If you've had OSHA confined space training, say so.
29. How do you protect yourself from heat-related illness during summer service calls?
What they're evaluating: Whether you take this seriously. Heat stroke is a real occupational hazard for HVAC techs working on rooftops and in attics in August.
How to answer: Hydrate before you're thirsty, not after. Work the attic first thing in the morning when possible, not at 2 PM. Take regular breaks in cooler environments when working extended periods in high-heat conditions. Know the difference between heat exhaustion (heavy sweating, weakness, cool/pale/moist skin) and heat stroke (hot/dry skin, confusion, loss of consciousness) — heat stroke is a medical emergency. Know your coworkers' signs if you're working as a team. Good shops have protocols around this; it's a reasonable thing to ask an employer about.
30. What's your understanding of Section 608 violations and the consequences?
What they're evaluating: Whether you understand that refrigerant venting isn't just bad practice — it's a federal violation with serious consequences.
How to answer: Intentional venting of refrigerants covered by Section 608 is a federal violation. Fines can reach up to $44,539 per day per violation under current EPA penalty guidelines. More immediately, your EPA certification can be revoked. The liability doesn't just fall on the company — individual technicians can be held responsible. The practical takeaway is that recovering refrigerant properly isn't optional even when it's inconvenient. Most good companies have zero tolerance here.
31. How do you handle working with natural gas equipment — what are the safety checks you do before firing up a furnace?
What they're evaluating: Gas safety awareness and whether you have a systematic pre-fire checklist.
How to answer: Check for gas leaks at every connection before firing — use soap solution or a gas detector at the regulator, shutoff valve, manifold, and burner connections. Verify flue is intact and clear. Check that the heat exchanger area is clear of debris and combustibles. Verify gas pressure at the manifold inlet. Confirm airflow is adequate before firing — inadequate airflow causes overheating and trips limits. Light the burner and verify stable flame. Run a combustion analysis if you have the equipment. Verify CO levels in the flue and in the supply air before leaving the job.
Section 4: Behavioral and Soft Skills (Questions 32-38)
These questions make techs uncomfortable because there's no technical answer to memorize. But they're where a lot of the hiring decision actually gets made.
32. Tell me about a time you dealt with an angry or frustrated customer. What happened and how did you handle it?
What they're evaluating: Whether you get defensive, make excuses, or actually take care of people. Service managers hear about problem customers constantly — they need techs who don't make the situation worse.
How to answer: Pick a real situation. Don't say you've never had an angry customer — everyone has. The structure that works: let them talk without interrupting, acknowledge what they're frustrated about, take ownership of what you actually can control, and explain clearly what you're going to do. Don't promise what you can't deliver. Don't throw your company under the bus even if the problem was the company's fault. Close by describing the outcome.
33. Do you prefer working alone or as part of a crew?
What they're evaluating: Fit for the role they're hiring. Commercial and industrial work often involves crews; residential service is often solo. Neither preference is wrong, but a mismatch creates problems.
How to answer: Be honest, but also demonstrate flexibility. If you prefer solo work because you're efficient independently, say that — but also show you can collaborate. If you prefer crew work, show you can also work independently when needed. The worst answer is "whatever you need" with no self-awareness behind it.
34. How do you handle a situation where you're not sure what's wrong with a system?
What they're evaluating: Intellectual honesty versus overconfidence. Techs who fake certainty are more dangerous than techs who ask for help.
How to answer: Describe a systematic process for narrowing down the problem when you're stuck — checking manufacturer technical literature, calling technical support, reaching out to a more experienced coworker, or in some cases telling the customer you need to do additional research before recommending a repair. The answer that kills candidates here is "I always figure it out" — that's not credible and signals someone who would replace parts guessing before admitting they're stuck.
35. What would you do if you showed up to a job and the equipment was obviously installed incorrectly — wrong size, improperly charged, ductwork that can't be right — but the previous tech was someone from your own company?
What they're evaluating: Integrity and professional judgment. This situation happens and how you handle it reveals a lot about your character.
How to answer: The right answer is to document what you found accurately, repair what you can, and report the situation to your manager — not cover it up, not throw a coworker under the bus publicly to the customer. The customer deserves an honest assessment of their system's condition. Your manager needs to know about quality problems. You don't make it your mission to investigate why it happened.
36. How do you manage your truck and keep track of parts inventory?
What they're evaluating: Organization and professional habits. A tech who runs out of common parts in the field or can't find their tools is a liability.
How to answer: Describe your actual system — weekly stock checks, tracking what you use and restocking before it runs out, keeping the truck organized so you can find what you need quickly, calling ahead to the supply house when you know you need something unusual. If your current company uses field management software for parts tracking, mention that. Companies that run tight dispatch operations need techs who don't lose time hunting for parts.
37. Tell me about a situation where you disagreed with your supervisor about how to handle something. What did you do?
What they're evaluating: Maturity and whether you're difficult to work with or whether you handle disagreements professionally.
How to answer: Pick a real example. Explain the disagreement factually without editorializing about who was right. Describe how you raised your concern — directly and privately, not in front of customers or coworkers. Describe the outcome. If your supervisor's approach turned out to be right, say so. If yours did, say that too — but without making it about winning.
38. How do you handle the physical demands of the job — attic work, rooftop work, confined spaces?
What they're evaluating: Whether you're realistic about the physical nature of the work and whether you have any conditions that would limit your ability to perform the job safely.
How to answer: Be direct and honest. If you've been doing the work for years, say that and describe the conditions you've worked in. If you have any relevant physical limitations, you're better served being upfront than having it discovered on your first week. Good companies accommodate reasonable needs; bad companies you don't want to work for anyway.
Section 5: Career and Motivation (Questions 39-40 and Beyond)
These questions seem easy, but they trip up more techs than you'd expect.
39. Why HVAC? How did you get into this trade?
What they're evaluating: Whether you chose this work or fell into it. Neither is disqualifying, but techs who are genuinely engaged with the trade are more reliable long-term hires.
How to answer: Tell the truth. If you fell into it, say so — lots of great techs did. But connect it to what you find satisfying about the work now. Diagnostic work appeals to people who like problem-solving. The trade offers good income without a four-year degree. You like working with your hands. The job is never the same twice. Whatever actually motivates you to show up and do good work — say that.
40. Where do you see yourself in five years?
What they're evaluating: Ambition and retention. A service manager doesn't want to invest in training someone who'll leave in six months. They also don't want a tech with no interest in growing.
How to answer: Match your answer to what the company can realistically offer. If you're interviewing at a shop where there's room to move into a lead or service manager role, express interest in that trajectory. If you want to stay on the tools and develop specialty expertise — refrigeration, controls, commercial chillers — say that. The worst answer is a vague "I just want to grow" with no specifics behind it.
Questions You Should Ask the Employer
An interview is a two-way evaluation. If you walk out without asking anything, you've either left important information on the table or signaled that you'll take any job regardless of fit. Here are six questions worth asking every time.
"Do you offer take-home trucks, and what's the policy?" Take-home vehicle policy affects your actual compensation significantly. A company that lets you take your truck home eliminates your commute from the equation. Ask whether it's personal-use allowed or strictly commute-only, and whether you're responsible for fuel on personal use.
"What does the on-call rotation look like?" This is one of the most important quality-of-life questions in HVAC. How many techs share on-call? How often are you on? What's the call volume on a typical on-call week? Is there an additional pay structure for on-call hours or after-hours calls? Small shops with two or three techs may have you on call half the year; larger operations spread it out further.
"What's the pay structure — flat rate, hourly, or some combination?" Flat rate rewards efficiency but can feel punishing on difficult or unusual jobs. Hourly is more predictable but doesn't reward techs who work faster. Some shops use a blended model. Knowing the structure helps you understand your earning potential accurately. Check your market value score and salary benchmarks before the interview so you know what the market looks like in your area.
"What does the tool allowance look like, and are there any tools the company provides?" Some companies provide core test instruments; others expect you to bring everything. Tool allowances vary from nothing to $1,000+ per year in credits at supply houses. Specialty tools for specific equipment are typically company-provided. Know what you're expected to bring.
"Do you support continuing education — manufacturer training, NATE prep, certifications?" Good shops invest in their techs because it pays off for the company. Ask whether they cover training costs, whether they pay your hourly rate while you're in training, and what certifications they encourage or require. If they have no answer or seem uninterested in the question, that tells you something.
"What does a typical career path look like for a tech at this company?" This reveals whether the company thinks about retention and development or whether they cycle through techs. A shop with a clear answer — "our last two service managers came up from the field" — is a different culture than one that has no idea how to respond.
Small Shop vs. Large Company: Adjusting Your Approach
If you're interviewing at a small owner-operated shop, don't overthink the format. The owner is evaluating you as a person as much as a technician. Show up on time, dress appropriately for the trade (clean work clothes, not a suit), and be direct. Ask about the business — what markets they serve, what equipment they specialize in, what the team looks like. Owners appreciate techs who want to understand the operation, not just collect a paycheck.
At a large regional or national company, the HR screen is mostly about confirming your experience matches the job description and checking for obvious red flags. Save your technical depth for the service manager interview. In the technical round, be specific — vague answers about "good troubleshooting skills" don't score well on a structured rubric. If there's a skills assessment, treat it seriously. A company that tests candidates in the field before hiring is usually the kind of company that runs a well-organized operation.
In either setting, your references matter more than people think. Have two or three former supervisors or leads who will pick up the phone and say something specific about your work — not just confirm your dates of employment.
Getting Prepared
Read through these questions and think about which ones you'd struggle with. The technical questions have right answers — if you're fuzzy on superheat and subcooling or your evacuation process is "pull it down for 30 minutes," address that before you walk into an interview. The behavioral questions don't have right answers, but they have better and worse ones. Think about your real experiences and how to describe them clearly.
The commercial vs. residential distinction matters for how you position yourself — if you're making a transition between the two, read up on commercial vs. residential HVAC career differences before your interview so you can speak to it intelligently.
Before your interview, check your market value score — knowing your number when the compensation question comes up puts you in a stronger negotiating position. When you're ready to start applying, browse open HVAC positions on HVACJobs.IO and filter by location, job type, and experience level. The right position and the right preparation at the same time — that's when interviews go well.
Frequently Asked Questions
What questions do HVAC employers ask most in interviews? Technical questions about the refrigeration cycle, superheat and subcooling, electrical troubleshooting, and refrigerant handling are the most common. Safety questions about EPA 608 compliance and lockout/tagout procedures come up in nearly every interview. Behavioral questions about handling callbacks and customer complaints round out the standard format.
How long does an HVAC job interview typically take? At a small shop, expect 30-60 minutes. At a large company with an HR screen plus a technical interview, the full process can take two or three separate meetings over a week or two. Some companies add a hands-on skills assessment, which can add another hour.
Do HVAC companies test your skills during the interview? Many do, especially for service technician roles. A common format is a practical assessment with a multimeter and a piece of live equipment in the shop. Some companies use a written technical test. Be prepared for either.
What should I bring to an HVAC interview? Copies of your certifications — especially EPA 608, NATE if applicable, and any manufacturer training certificates. Your driver's license. A list of references. If you carry your own test instruments (multimeter, manifold gauges), it's not unusual to bring them to demonstrate your setup, especially if the interviewer is likely to ask about your tools.
How should I answer technical questions I don't know the answer to? Be honest. Say you're not certain of the exact answer but explain how you'd find it — consulting the service literature, calling manufacturer tech support, or working through it systematically. Faking technical knowledge is easy to detect and immediately disqualifying. Admitting uncertainty while showing you have a process for resolving it is a perfectly acceptable answer.
What's the biggest mistake HVAC technicians make in interviews? Giving vague answers. "I'm a good troubleshooter" is meaningless. "I've spent three years primarily on commercial RTUs and I'm most comfortable diagnosing refrigerant circuit problems" tells an interviewer exactly what they need to know. Be specific about your experience, your equipment knowledge, and your limitations.
Should I negotiate salary in an HVAC interview? Not in the first conversation. Get an offer first. Once you have a specific number, you can negotiate — and you'll negotiate from a stronger position if you know what the market pays. Check salary benchmarks for your market before the interview so you walk in knowing your number.
What's the difference between EPA 608 Type II and Universal certification? Type II covers high- and very high-pressure refrigerants — which includes most of the equipment in commercial and residential HVAC. Universal certification covers all equipment types including low-pressure (Type III) equipment like large centrifugal chillers that use R-123. If you're doing any chiller work or want flexibility across all equipment types, Universal is the right credential.