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

• Air is blowing but it is warm A dirty filter, a frozen coil, or a refrigerant leak.
• It cools, just never enough on hot days Undersized system, duct leakage, or a coil that needs cleaning.
• 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 before it damages the compressor.
• I want the full checklist before I call anyone Seven checks that resolve a large share of no-cool calls.

• Nothing happens at all when I turn it on Thermostat batteries, a tripped breaker, or the float switch in the 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 or a thermostat calling continuously.
• It turns on and off every few minutes Short cycling, usually an oversized system or a restriction.
• The outdoor fan is not spinning Most often a failed capacitor, which is one of the cheaper repairs.
• It stopped after a power outage A tripped breaker or a control board that needs a 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 compressor component. This one gets worse, not better.
• Squealing or screeching A belt 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. 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 will not ignite Igniter or flame sensor, the two most common and least expensive failures.
• It clicks but never lights Same family, walked through step by step.
• 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.

• Water is leaking or the drain pan is full shut it off first A clogged condensate line. Left alone it stains ceilings.
• 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 introduced at install.
• I have a Honeywell thermostat acting up Model-specific reset 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.

Anything involving refrigerant, the sealed system, gas, or the inside of the electrical panel needs a licensed tech, and in California refrigerant work legally requires EPA Section 608 certification. Filters, thermostat batteries, breakers, condensate lines and clearing the outdoor unit are all homeowner jobs, and our maintenance guides walk through those.

When you do need a pro, Climate Pros SD matches you with a licensed local one across San Diego County. Two questions worth asking whoever you call: is a tech available today, yes or no, and what is the diagnostic fee as a dollar figure. A company that will not answer either one on the phone is telling you something.

If the system is old enough that you are weighing the repair against replacing it, our repair versus replace guide has the math, and every service we cover is listed with what it includes.