HVAC not working? Start with what it is actually doing.

• Air is blowing but it is warm A dirty filter, a frozen coil, a failed capacitor outdoors, or a refrigerant leak.
• It cools, just never enough on 110F days A dirty condenser coil, duct leakage, or a system that was never sized for the heat.
• Some rooms are cold and others are not Duct leakage or a balance problem, not a broken AC.
• There is ice on the refrigerant line or the coil Airflow starvation or low refrigerant. Turn it off so it thaws before it damages the compressor.
• It quit working right after a dust storm A filter or outdoor coil loaded with dust. Check the filter first.
• I want the full checklist before I call anyone The free checks to run before you pay for a visit.

• Nothing happens at all when I turn it on Thermostat batteries, a tripped breaker, or the float switch in a full drain pan.
• It keeps tripping the breaker shut it off first A hard-starting compressor or a short. Stop resetting it after the second trip.
• It runs constantly and never shuts off A stuck contactor, a thermostat calling nonstop, or a system losing the fight with the heat.
• It turns on and off every few minutes Short cycling, often an oversized system, a restriction, or a failing part.
• The outdoor fan is not spinning Often a failed capacitor or fan motor. Turn it off so the compressor does not overheat.
• It stopped after a monsoon power outage A tripped breaker or a control that needs a proper reset sequence.
• I just want to reset it properly There is a right order and a right wait time.

• Banging or clanking A loose or failing component, sometimes in the compressor. This one gets worse, not better.
• Squealing or screeching A belt on a package unit or a failing motor bearing.
• Hissing or bubbling Often a refrigerant leak, sometimes a duct leak.
• A loud noise I cannot place Match the sound to the cause before anyone quotes you a part.
• It smells musty, burning, or like rotten eggs shut it off first Musty is usually the coil or drain. Burning and rotten eggs are both stop-now situations.
• The heat pump is making a noise Some heat pump sounds are normal defrost. Others are not.

• The furnace clicks but never lights Ignitor or flame sensor, the usual first-cold-night failures.
• It is the first cold night and the heat will not come on A system idle since spring: dust, a weak ignitor, or a thermostat still set to cool.
• The furnace blows cold air A safety limit shut the burner down, often from a clogged filter.
• The heat pump is not heating Reversing valve, defrost control, or auxiliary heat not engaging.
• The heat pump outdoor unit is frozen or steaming Steam during defrost is normal for a few minutes. Ice that stays is not.

• Water is leaking or the drain pan is full shut it off first A clogged condensate line. Left alone it stains ceilings.
• The mini split head is dripping water A blocked drain or a head that is not level.
• The thermostat screen is blank or unresponsive Batteries, or the float switch cutting power, before anything expensive.
• My smart thermostat will not cool Usually a wiring or C-wire issue from the install.
• I have a Honeywell thermostat acting up Model-specific resets and fault codes.
• I think the system is low on refrigerant Refrigerant does not get used up. If it is low, there is a leak.

• It worked in June and quit cooling in the monsoon Humidity, not a broken cooler. Evaporative cooling needs dry air.
• The pads are dry or the water is not flowing The pump, the float valve, or a clogged distribution line.
• It smells musty Old pads or standing water in the pan.
• Water is leaking onto the roof A float valve stuck open or a cracked pan.

Anything involving refrigerant, the sealed system, gas, or the inside of the electrical panel needs a licensed pro. Federal rules require EPA Section 608 certification for anyone who handles refrigerant, and in Arizona HVAC contractors are licensed by the Registrar of Contractors, which you can check at roc.az.gov. Filters, thermostat batteries, breakers, condensate lines and clearing the outdoor unit are homeowner jobs, and our maintenance guides walk through those.

When you do need a pro, Climate Pros Tucson matches you with a licensed local company across the Tucson area. Two questions worth asking the matched company: can a tech come, yes or no, and what is the diagnostic fee as a dollar figure. A company that won't answer either one on the phone is telling you something. If an older adult or someone at risk is in a hot house, say so when you call, and see our emergency HVAC page.

If the system is old enough that you're weighing the repair against replacing it, our repair versus replace guide walks the decision without invented prices, and every service we refer is listed with what that scope usually includes.