HVAC problems

Start with the free checks. Is the filter dirty? Is the breaker tripped? Is the thermostat on the right mode with fresh batteries? Is the outdoor unit's disconnect switch on? Is anything blocking the return vents? A surprising share of service calls end with the technician doing exactly one of these.

Short cycling — the system turning on and off in short bursts — is worth taking seriously. It can mean a dirty filter, a failing capacitor, a refrigerant problem, or an oversized system that was never sized correctly in the first place. ACCA's Manual J load calculation exists precisely to prevent that last one.

Two symptoms are safety issues, not comfort issues: a gas smell, and a carbon monoxide alarm. Leave the house and call the gas utility or 911. Do not wait for an HVAC appointment. Similarly, treat a cracked heat exchanger diagnosis as something to verify with photos and a second opinion — it is a real hazard and also a common upsell.

How to choose

Change the filter first, always

Carrier's guidance is to change filters at least every other month to keep the system from overworking. A clogged filter can cause weak airflow, a frozen coil and short cycling all at once.

Refrigerant is not consumed — if it's low, there's a leak

A contractor who tops up refrigerant every season without finding the leak is selling you a subscription. Ask for leak detection and a repair plan.

Ice on the indoor coil or refrigerant line means shut it off

Turn the system to fan-only and let it thaw before a technician arrives. Running a frozen system can damage the compressor, which is the expensive part.

Rooms that are always too hot or cold are usually a duct problem

Adding a bigger unit will not fix bad duct design. This is a Manual D and airflow question, and it is often cheaper to fix than to replace equipment.

Get the diagnosis in writing

Part name, what failed, what it costs, and what it costs to fix versus replace. If the technician cannot give you that on paper, get a second opinion.