What is wrong? › Commercial HVAC
Warm air with normal airflow: condenser fan, capacitor, compressor or refrigerant
If the condenser fan is dead the compressor is overheating on every cycle, and a compressor is the most expensive part in the unit.
What is probably happening
- The condenser fan motor or its capacitor has failed. The unit runs but cannot reject heat, then trips on high pressure and restarts. That is the start-stop pattern.
- A dirty condenser coil doing the same thing more slowly, especially near a kitchen exhaust or cottonwood trees.
- A refrigerant leak, so the unit runs and runs but the air never gets cold.
- A compressor that has failed, which is a repair-or-replace decision on an older unit.
Do this in the next five minutes
- Turn cooling Off at the thermostat. Running a unit that is short-cycling or has a dead fan makes the damage worse.
- Note what you heard: humming, clicking, starting and stopping every few minutes. Tell the technician.
- Check the lease if you rent (see the ownership leaf). Then call for a same-day visit.
- Ask for the model and serial from the data plate so you know the unit's age before anyone talks replacement.
- Keep doors closed and stock cool while you wait.
Do not
- Do not go on the roof to look at the fan. OSHA's fall protection rule starts at 4 feet, and the fan blade is unguarded from above.
- Do not accept a refrigerant top up without a leak search and a written leak location.
- Do not decide on replacement on the phone. Ask for readings first.
Who to call
A licensed commercial HVAC contractor with EPA Section 608 Type II or Universal certification
Rooftop units are high pressure appliances. Anyone opening the refrigerant circuit must hold EPA Type II or Universal certification.
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What it should cost
$100 to $3,000, averaging $350
HVAC repair, national range. A capacitor or fan motor is at the low end, a compressor at the high end
Source: Angi, HVAC repair cost, updated August 2026. View source
National published range, not a quote for your job. The full cost table for this trade is on the commercial hvac page.
Ask this contractor, on the phone, before anyone comes out
Tap each one as you ask it.
- What did you find: fan motor, capacitor, contactor, coil, leak or compressor? Please write it down.
- If you found a leak, where is it and what will it cost to fix it rather than top it up?
- What refrigerant does this unit use, and does that change the repair price?
- If the compressor has failed, what is the unit's age and what is the repair versus replace cost side by side?
End the call if
- A whole-unit replacement quote on the first visit with no pressure or electrical readings.
- Refrigerant added with no leak search.