Home A/C coils are frozen ... any action required besides leaving A/C off for a while

If the coils freeze up on your home A/C unit, does leaving the unit off to “thaw” for a day or two solve the problem? Or do I have to perform some kind of maintenance (or call someone to come out)?

Not really data but more of an anecdote, but when this happened to us a few months ago, leaving the A/C off solved things for a while, but then the coils would freeze up again… until we called in a pro, who replaced the unit’s main board (yeah, even A/C’s have those now) – to the tune of about $120 :eek:. But now it works perfectly.

So until somebody who actually knows something shows up, I’ll say you probably need to call in the pros.

ETA: The service person said the part of the board that had gone was some feedback circuit that controlled unit defrosting. This is the same guy who installed the unit originally and whom I’ve known for well over 10 years and trust completely, so I don’t think he was fleecing me.

Yes, you have a problem that requires service. Usually low on refrigerant.

Couple things you can try. Low refrigerant is one cause of coil icing, but another is low airflow across the coil. This can be caused by the blower motor not running or a broken/slipping drive belt. It can also be caused by dust accumulation in the coil, which can be solved by blowing it out, or the filters might simply need to be changed. Stating flat out that you need professional service, however, is inaccurate at best.

If you turn off the compressor but leave the fan running, the coils will defrost much faster.

Thanks for the advice, everyone. :slight_smile:

Ours was almost always dirt on the coils. (Old unit - it was a nasty job in a bad location to clean them, so it tended to be ‘forgotten’.)

I’d check the coils and replace the filters first. If that doesn’t fix it, call for service.

If problem is not solved you can experience carry over (commonly called slugging) the end result can be a new compressor.

Possable causes

  1. Dirty air filter
  2. Dirty evap coil
  3. restriction in the duct work.

These can be cleared by a DYI
4. Low charge
5. Liquid line restriction
6. Problem with expansion device
7. Control board problems
And a few others.

Calling a pro can be less expensive than attempting it yourself.