Commercial HVAC repairs: what to check before you call.
By Tyler Wayne, FMP · Working B2B HVAC Rep on the Wasatch Front · Updated October 2026
Before you call for a commercial HVAC repair, check the thermostat or schedule, the breaker and disconnect, the filter and any error codes. Write down what the unit is doing and when it started. If you smell gas, hear banging from a heat section or a carbon monoxide alarm goes off, skip the checks and call right away.
Safety first
- Smell gas: leave the area and call your gas utility and your service provider.
- Carbon monoxide alarm: get people out and call for help.
- Don't open electrical panels or go on a roof without the right training and access.
Quick checks a facility team can do
1. Thermostat and schedule
Is it set to the right mode and temperature? Is the building schedule in unoccupied mode? A surprising number of no heat calls are a schedule that never switched to winter.
2. Power
Check the breaker for that unit. A tripped breaker can be reset once. If it trips again, leave it off and call.
3. Filters
A badly loaded filter can freeze a coil in summer or trip a heat section on high limit in winter.
4. Condensate
Many units shut themselves off when the condensate drain backs up. Water around the unit or ceiling stains are a clue.
5. Error codes
Many units and thermostats show a code or a blinking light. Take a photo of it.
What to tell the tech
- Which unit, and what area it serves.
- What it's doing: no heat, no cooling, noise, smell, water, tripping.
- When it started and whether it's constant or on and off.
- Anything that changed recently: storms, power outages, roof work, tenant changes.
- Photos of codes, the nameplate and anything unusual.
Common repairs by season
Summer
- Failed capacitors and contactors on hot afternoons.
- Condenser coils clogged with cottonwood fluff, which raises pressure and trips the compressor.
- Low refrigerant from leaks.
Winter
- Dirty flame sensors and failed igniters on gas heat sections.
- Cracked heat exchangers found at startup.
- Frozen coils from outside air dampers stuck open.
- Boiler lockouts on the first cold mornings.
Repair or replace?
If a unit keeps coming back, read repair or replace a 15 year old rooftop unit. Most repeat repairs show up first in good preventative maintenance reports.
Repairs by city
Local notes by city: Salt Lake City, Sandy, West Jordan, Draper, Lehi, Saratoga Springs, American Fork, Orem and Provo.
Common questions
Should I reset a unit that keeps shutting off?
Reset a tripped breaker once at most. If it trips again or the unit locks out repeatedly, leave it off and call. Repeated resets can turn a small problem into a big one.
What should I do if I smell gas near a rooftop unit?
Leave the area, keep people away and call your gas utility and service provider.
Why does my rooftop unit stop cooling on hot afternoons?
Common causes are dirty condenser coils, a failed capacitor or contactor, or low refrigerant. A tech can check all three on one visit.