AC repair second opinion: when to get one, and what to check first

An AC tech tells you the compressor is shot, or the coil is leaking, or the whole system needs to go — and the quote has a comma in it. Before you sign, it's worth knowing whether the diagnosis holds up. Most techs are honest, but AC problems are easy to misdiagnose and easy to upsell, and a second opinion costs far less than the wrong repair.

When a second opinion is worth it

• The quote is over about $1,000, or you're being told to replace the whole system.
• The diagnosis is vague — "it's low on Freon," "it's old," "the system is failing" — with no specific failed part named.
• You're told to add refrigerant without a leak search. Refrigerant doesn't get used up. If it's low, it's leaking, and topping it off without finding the leak means paying again next summer.
• The unit is under 10–12 years old and you're hearing "replace it."
• You're being pressured to decide today, or offered a discount that expires when the tech leaves.

Cheap failures that get misread as expensive ones

A lot of "dead AC" calls come down to a handful of inexpensive parts. Ask whether these were checked before anything bigger is on the table:

• Capacitor — a common cause of the outdoor unit humming but not starting. A swollen or leaking top is a giveaway.
• Contactor — the switch that powers the outdoor unit. Pitted or stuck contacts cause no-start or won't-shut-off problems.
• Clogged condensate drain — trips the float switch and shuts the system down. Often fixed by clearing the line.
• Dirty filter or iced-up indoor coil — low airflow can make a healthy system look like it's failing.
• Thermostat or wiring — dead batteries, a wrong setting, or a loose low-voltage wire.

What to check yourself before anyone comes back

1. Replace or check the air filter.
2. Confirm the thermostat is on Cool, set below room temperature, with fresh batteries.
3. Check the breakers for the indoor and outdoor units and the outdoor disconnect switch.
4. Look at the outdoor unit: is the fan spinning? Is the coil packed with dirt or grass clippings?
5. Look for ice on the refrigerant lines or indoor coil. If you see ice, shut the system off and let it thaw before running it again.

Don't open the electrical panels on the units themselves — capacitors hold a charge even with the power off.

Questions to ask the contractor

• Which specific part failed, and how did you test it?
• Can I see the readings, or the old part?
• If it's low on refrigerant, where is the leak, and is the leak repair in this quote?
• Is the part under the manufacturer's warranty? Many units carry 5–10 year parts warranties if registered.
• What would the repair cost versus replacement, line by line?

Repair or replace?

A common rule of thumb: multiply the unit's age by the repair cost. If the number is over about $5,000, replacement starts to make sense; under it, repair usually wins. Age, refrigerant type, and how often it's broken down recently matter too — a 15-year-old system on its third major repair is a different story from a 7-year-old one with a bad capacitor.

Common questions

How much does an AC diagnostic usually cost?

Many companies charge a service-call or diagnostic fee, often somewhere around $75 to $200 depending on the area and time of day. Some credit it toward the repair if you hire them.

Is it rude to get a second opinion on an AC repair?

No. Getting a second opinion on a large repair is normal, and a good contractor will expect it. Ask for the diagnosis in writing so the second reviewer can see exactly what was found.

My tech says I just need more Freon. Is that right?

Refrigerant runs in a closed loop and isn't used up. If the system is low, there is a leak somewhere. Adding refrigerant can get you cooling again, but without finding and fixing the leak it will likely come back.

Can you tell what's wrong from photos?

Often, yes. Photos of the outdoor unit, the data plate, the indoor unit, the thermostat, and the written quote are usually enough to tell whether a diagnosis makes sense and what questions to ask. Some problems still need hands-on testing, and we'll tell you when that's the case.

This guide is general information, not a diagnosis of your specific home. For anything involving gas, a burning smell, sparking, or water near electrical, shut it off and call a licensed pro right away. See our disclaimer.