Question 1

What can I safely check on my commercial AC before calling a technician?

Accepted Answer

You can check the thermostat mode and setpoint, replace the batteries if the display is blank, look at the breaker, inspect or replace a dirty air filter, make sure supply and return vents are open and unblocked, and look for a visible condensate drain backup. Do not open electrical panels on the unit.

Question 2

There's ice on my AC lines or coil — what should I do?

Accepted Answer

Switch the system off at the thermostat and leave it off. Do not chip or scrape the ice off the coil — you will damage the fins. Let it melt on its own, then call. Ice usually means a low refrigerant charge from a leak or restricted airflow from a dirty filter.

Question 3

Why is my AC blowing warm air even though the fan is running?

Accepted Answer

The air-handling side is working but the refrigeration side is not. Common causes are a low refrigerant charge from a leak, a compressor that has lost capacity, or a contactor that is not closing to start the outdoor unit. Check the thermostat is set to Cool below room temperature, check the filter, and confirm the outdoor unit is actually running.

Question 4

What does it mean if the outdoor or rooftop unit won't come on at all?

Accepted Answer

It points to an electrical or control failure upstream of the refrigeration loop — a tripped breaker or disconnect, a failed contactor, a bad capacitor, or a thermostat that is not making the call. Check the breakers and the thermostat first.

Question 5

Why is water leaking from my indoor AC unit?

Accepted Answer

The condensate drain is clogged or backed up, so the moisture the coil pulls from the air has nowhere to go and overflows the pan. A backed drain can also trip a safety float switch that shuts the whole unit down.

Question 6

Should I keep running the AC if it is making a new noise?

Accepted Answer

If the noise is severe, switch the unit off to prevent further damage. A new noise usually points to a specific mechanical failure — a failing fan motor, a worn compressor, a failing contactor, or a refrigerant issue. Note whether the noise is from the indoor unit or the outdoor/rooftop unit.

Symptom	Likely Causes
Blowing warm air	Low refrigerant charge from a leak, compressor lost capacity, or a contactor not closing to start the outdoor unit.
Won't turn on	Tripped breaker, blown fuse, thermostat not calling for cooling, or a failed contactor or capacitor at the unit.
Runs but the room won't cool down	Low refrigerant charge, compressor losing capacity, restricted airflow from a dirty filter, or a partially iced coil.
Ice on the lines or coil	Low refrigerant charge from a leak or restricted airflow starving the coil. Switch the system off and let it melt.
Water leaking inside	Clogged or backed-up condensate drain overflowing the pan; can also trip a safety switch that shuts the unit down.
Turns on and off a lot (short cycling)	Restricted airflow from a dirty filter or blocked vents, a tripping safety switch, or a failing contactor.
Loud or new noise	Failing fan motor, worn compressor, loose or failing contactor, or a refrigerant issue.
Outdoor/rooftop unit not running	Tripped breaker or disconnect, failed contactor, bad capacitor, or a control/thermostat issue.
Thermostat set wrong	Not set to Cool, setpoint at or above room temperature, dead batteries, or the thermostat not making the call.

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