HVAC Technician Interview Questions + Scorecard

HVAC technician interview questions for shop owners: a 3-step interview, 31 questions, good answers, red flags, a 1-5 scorecard, and questions to avoid.

A bad hire costs you callbacks, unhappy customers, and weeks of training that walks out the door. A good interview won't catch everything, but a consistent one catches a lot more than "seems like a good guy." This guide gives you a simple three-step process, 31 questions grouped by what they test, what a strong answer sounds like, red flags to watch for, a printable scorecard, and the questions you should not ask.

This is practical advice, not data. There are no made-up statistics here. Nothing in this guide is legal advice. Employment law varies by state and city, so check with an employment attorney or your state labor agency before you change how you hire.

Before the interview: know what you're hiring for

Write down three things before you post the job:

• The level. Helper/apprentice, service tech, install tech, or lead tech. The questions and the bar are different for each.
• The must-haves. For example: valid driver's license and a clean enough record to be insured on your trucks, EPA Section 608 certification if they'll handle refrigerant, and any state license your market requires.
• What "good" looks like at 90 days. Running calls alone? Hitting a callback target? Writing clean tickets? If you can't describe it, you can't interview for it.

If you're still deciding whether you can afford another tech at all, run the numbers first with the hire another tech calculator. For pay ranges and what other shops offer, see HVAC tech pay and hiring benchmarks.

The three-step interview

Use the same steps and the same core questions for every candidate at the same level. It's fairer, it makes candidates easier to compare, and it gives you a written record of why you chose who you chose.

Step 1: Phone screen (15 minutes)

The goal is to rule out obvious mismatches before anyone drives across town.

• Confirm the must-haves: license to drive, certifications, availability for the schedule and on-call rotation you actually run.
• Ask 3 or 4 questions: why they're looking, what kind of work they've been doing, what they want next, and what pay range they're looking for.
• Tell them the pay range and schedule up front. It saves both of you time.
• Notice the basics: did they answer the phone or call back promptly? Were they clear and polite? That is roughly how they'll sound to your customers.

Step 2: In-person interview (45 to 60 minutes)

Two people from your shop if you can (for example, the owner and a lead tech or service manager). Both score separately on the same sheet, then compare.

• Technical questions (pick 5 to 8 from the list below, matched to the level).
• Customer and communication questions (pick 3 or 4).
• Reliability and attitude questions (pick 3 or 4).
• Lead tech questions if you're hiring a lead.
• Leave 10 minutes for their questions. Good candidates ask good questions.

Step 3: Ride-along or bench test (2 to 4 hours)

Talking about a repair and doing one are different skills. Before you make an offer, watch them work.

• Bench test: set up a unit or trainer in the shop with a planted fault (a failed capacitor, a bad contactor, a miswired thermostat, a low charge on a unit you control). Ask them to diagnose it and talk you through what they're doing.
• Ride-along: they shadow a senior tech on real calls. Watch how they treat the homeowner, how they handle tools and the customer's home, and whether they ask smart questions.
• Be clear about pay. If the working interview involves real work, check your state's rules on paying for it. Many shops simply pay for the hours as a matter of course.
• Score it on the same scorecard below.

Technical questions

Pick the ones that fit the level. You don't need a lead-tech answer from an apprentice, but you do want to see how they think.

Refrigeration basics

• Q1. Walk me through the refrigeration cycle, starting at the compressor. Good answer: compressor raises pressure and temperature of the vapor; condenser rejects heat and the refrigerant condenses to liquid; metering device drops the pressure; evaporator absorbs heat and the refrigerant boils to vapor; back to the compressor. Bonus if they mention where superheat and subcooling are measured.
• Q2. What's superheat, what's subcooling, and when do you charge by each? Good answer: superheat is how far the suction vapor is above its saturation temperature; subcooling is how far the liquid is below its saturation temperature. They should know that fixed-orifice systems are typically charged by superheat and TXV/EEV systems by subcooling, and that they follow the manufacturer's charging chart or instructions.
• Q3. A customer says the system runs all day and the house won't cool down. High superheat, low subcooling. What are you thinking? Good answer: points toward an undercharge, likely a leak, and they'd look for it rather than just add refrigerant. They should also mention checking airflow and filters first.
• Q4. Low superheat, high subcooling on a TXV system. What could that be? Good answer: possible overcharge, or a restriction or problem on the high side. What matters is that they reason through it and mention confirming with other readings, not guessing.
• Q5. How do you find a refrigerant leak, and what do you tell the customer? Good answer: electronic detector, bubbles, nitrogen pressure test, dye where appropriate; explains repair options and costs honestly instead of "topping it off" forever.

Electrical troubleshooting

• Q6. The outdoor unit isn't running but the indoor fan is. Walk me through your diagnosis. Good answer: a logical order. Check for 24V at the contactor coil, check line voltage, check the contactor, capacitor, and compressor/fan motor, check the disconnect and breaker. They work safely and verify power is off before touching anything.
• Q7. How do you test a run capacitor? Good answer: power off, discharge it safely, measure microfarads with a meter, compare to the rating and its tolerance.
• Q8. What's the difference between checking voltage and checking amperage, and when do you use each? Good answer: voltage tells you if power is present and at what level; amp draw tells you how hard a motor or compressor is working compared to its rating.
• Q9. Tell me about a no-heat call on a heat pump or furnace you had to figure out. What was it? Good answer: a specific, real story with steps. Vague answers ("I just fixed it") are a warning.
• Q10. What's your lockout/tagout habit on a service call? Good answer: they turn off and verify power at the disconnect, and they don't skip it when they're in a hurry.

Refrigerants, A2L, and certification

• Q11. What EPA Section 608 certification do you hold? Good answer: they know their type. EPA offers four types: Type I (small appliances), Type II (high- or very high-pressure appliances), Type III (low-pressure appliances), and Universal (all types). Most residential and light commercial split systems fall under Type II or Universal. EPA also states that Section 608 credentials do not expire, so an older card is still valid. Ask to see the card and keep a copy.
• Q12. Have you worked on any A2L refrigerant systems yet? What's different about them? Good answer: they understand A2L refrigerants are classified as lower-flammability, and they mention following the manufacturer's installation instructions, using tools and recovery equipment rated for A2Ls, and any training they've taken. "Never touched one, but here's what I know" is fine for a newer tech. For background, see our A2L refrigerant transition guide.
• Q13. How do you recover refrigerant, and what do you do with the recovery cylinder? Good answer: proper recovery machine and cylinder, doesn't overfill, labels and handles the cylinder correctly, never vents.
• Q14. When do you pull a vacuum, and how do you know it's good? Good answer: after opening a system or on new installs, pull down with a micron gauge, then do a decay test to confirm it holds.

Installs and airflow (for install techs)

• Q15. How do you check airflow on a system you just installed? Good answer: static pressure readings compared to the equipment's rated limits, temperature split, and checking the duct and filter setup.
• Q16. What do you check before you leave a new install? Good answer: a checklist. Charge verified, vacuum done, electrical tight, condensate draining, thermostat set up, area cleaned, customer walked through it.

Customer and communication questions

• Q17. A homeowner is upset because a repair costs more than they expected. What do you say? Good answer: stays calm, explains what's wrong and why in plain words, offers options, doesn't pressure or argue.
• Q18. How do you explain a failed part to someone who knows nothing about HVAC? Ask them to actually do it, for example with a capacitor. You want simple words and no talking down.
• Q19. Tell me about a time a customer was unhappy with your work. What happened next? Good answer: takes ownership, fixes it, tells you what they learned.
• Q20. How do you feel about presenting options and maintenance plans to customers? Good answer: sees it as helping the customer choose, not "selling." Red flag: either refuses to ever mention options, or talks about pushing people into things they don't need.
• Q21. What do you do when you arrive at a home and before you leave? Good answer: introduces themselves, uses shoe covers or drop cloths, explains what they'll do, cleans up, reviews the work and the invoice with the customer.

Reliability and attitude questions

• Q22. Why are you leaving your current job? Listen for a real reason. Some bad-mouthing is normal; blaming everyone for everything isn't.
• Q23. Tell me about a callback you caused. What happened and what did you change? Good answer: admits it happened and learned something specific. "I don't get callbacks" is a red flag. For more on this, see our guide to reducing callbacks.
• Q24. How do you handle the busy season: long days, on-call, back-to-back calls? Good answer: honest about what they can do, and shows they've done it before.
• Q25. What have you learned in the last year, and how did you learn it? Good answer: classes, manufacturer training, videos, a mentor, their own reading. Shows they keep getting better on their own.
• Q26. What would your last service manager say is your biggest weakness? Good answer: something real, plus what they're doing about it.
• Q27. How do you take care of the truck and inventory you're given? Good answer: keeps it stocked and clean, reports low parts, treats it like it matters.

Lead tech questions: mentoring and judgment

• Q28. How would you train a new helper on their first week? Good answer: a plan. Safety first, shadowing, then doing tasks with them watching, then alone. Patience matters more than speed.
• Q29. A newer tech keeps missing the same step and it's causing callbacks. What do you do? Good answer: talks to them privately, shows them the right way, checks the next few jobs, and brings it to the manager if it doesn't improve.
• Q30. When a junior tech calls you from a job stuck on a diagnosis, how do you help? Good answer: asks what they've checked and what readings they got, guides them to the answer instead of just giving it, and follows up afterward.
• Q31. Tell me about someone you trained. Where are they now? Good answer: a specific person they helped improve (no need for names), and pride in that.

Red flags

These aren't automatic disqualifiers, but they're worth probing:

• Can't explain the basics of the refrigeration cycle for the level they claim.
• Says they "top off" systems without looking for the leak.
• Skips safety steps, or jokes about working live when it isn't needed.
• Talks down to customers, or treats presenting options as tricking people.
• Every past boss, customer, and coworker was the problem.
• Never had a callback or a mistake.
• Late or no-show to the interview without a heads-up.
• Claims a certification but can't show the card.
• On the bench test: guesses and swaps parts instead of testing.

Printable scorecard (1 to 5)

Score each area right after the interview, before you talk to anyone else. 1 = well below what the role needs, 3 = meets the bar, 5 = clearly above. Write one sentence of evidence for every score. Use the same sheet for every candidate at the same level.

How to use it:

• Decide in advance what total, or what minimum in any one area, you need to move forward. For example, you might require at least a 3 in every technical area for a service tech, and let a helper score lower on technical items if they score high on attitude and learning.
• Compare scores between interviewers and talk through any area where you're 2 or more points apart.
• Keep the sheets. They show you chose based on job-related reasons.

Questions to avoid (the legal part)

This section only covers what we could confirm on U.S. Equal Employment Opportunity Commission (EEOC) pages. It is general information, not legal advice, and state or local laws may add more rules.

The basic rule. The EEOC says it is illegal to discriminate against a job applicant because of race, color, religion, sex (including transgender status, sexual orientation, and pregnancy), national origin, age (40 or older), disability, or genetic information. It also says that pre-employment questions should generally be limited to what's needed to decide whether someone is qualified for the job, and that questions that would reveal those protected traits if answered should generally be avoided. Source: EEOC, "Prohibited Employment Policies/Practices"

That same page also says:

• Employers should not ask for a photograph of an applicant; if needed for ID, it can be obtained after an offer is made and accepted.
• If you require a test, it must be necessary and related to the job. Keep your bench test focused on real tasks the job requires.

Specific topics to avoid before an offer:

• Marriage, kids, and pregnancy. The EEOC lists these as pre-employment inquiries that may be regarded as evidence of intent to discriminate: whether the applicant is pregnant, marital status or plans to marry, number and age of children or plans to have children, child care arrangements, spouse's employment, and spouse's name. Source: EEOC, "Pre-Employment Inquiries and Marital Status or Number of Children" Instead, ask the job question: "This role includes an on-call rotation one week a month and some Saturdays in summer. Can you meet that schedule?"
• Disability and health. The EEOC says employers generally cannot ask disability-related questions or require medical exams until after a conditional job offer. Before an offer, you may ask whether the applicant will need an accommodation to perform a specific job duty. Source: EEOC, "Pre-Employment Inquiries and Disability" Instead of "Do you have a bad back?", describe the duty and ask the job question: "This job involves working in attics and crawlspaces and carrying equipment up ladders. Can you perform these duties, with or without an accommodation?"
• Citizenship. The EEOC says most employers should not ask whether an applicant is a U.S. citizen before making an offer. Work eligibility is verified with Form I-9 after the person accepts the offer, and employers must not do the I-9 or E-Verify process before then. Source: EEOC, "Pre-Employment Inquiries and Citizenship"
• Religion. The EEOC says most employers should avoid questions about religious affiliation, such as place of worship, days of worship, and religious holidays. Source: EEOC, "Pre-Employment Inquiries and Religious Affiliation or Beliefs" If you need weekend coverage, just state the schedule and ask if they can work it.
• Arrests and convictions. The EEOC says an employer cannot refuse to hire people simply because they have been arrested. Employers can consider conviction records, but should look at the nature and seriousness of the offense, the time that has passed, and the nature of the job. It also notes that some states restrict asking about criminal history until later in the hiring process. Source: EEOC, "Arrest and Conviction Records" Check your state and city rules before you add this question to your application.

A simple test: if the question isn't about whether they can do this job, on this schedule, safely and well, don't ask it.

About EPA Section 608 certification

If the tech will attach gauges, add refrigerant, or remove refrigerant, EPA rules require Section 608 certification. EPA states that technicians must pass an EPA-approved test given by an EPA-approved certifying organization, that the credentials do not expire, and that apprentices are exempt as long as they are closely and continually supervised by a certified technician. That last point matters if you're hiring helpers who don't have their card yet. Source: EPA, "Section 608 Technician Certification Requirements"

After the interview

• Decide fast. Good techs often have more than one offer. Try to make a decision within a few days of the ride-along.
• Check references, using the same few questions for each: would you rehire them, how were they with customers, how reliable were they.
• Put the offer in writing: pay, schedule, on-call, tools and truck, benefits, start date.
• Plan the first 90 days before day one. The interview is only the start. Our guide to hiring and keeping HVAC technicians covers onboarding and why techs leave.
• Know what a miss costs. The technician turnover cost calculator shows what a bad hire or a quick quit actually costs your shop, which makes it easier to justify a careful interview.

Swap bench tests

If you'd like to trade interview questions and bench-test setups with other owners, post them in the Growth Room Discord.