AC interior coils freeze; can it be due to dirty exterior condensor?

[gm]

We had a recent incident were the coils in the return air plenum froze. The filter was not dirty. But due to a problem with our dryer, which vents next to the exterior condensor unit, there was a lot of lint on the exterior fan. The repairman said that was the problem, and want to charge $375 to acid wash it to clean it off.

I know coils can freeze from low freon levels and from low airflow over the coils due to a dirty filter, etc., but can the inside coils freeze due to inefficient heat transfer on the OUTSIDE unit?

Thanks.

[m Ransley]

The crook wants 375 to wash it! do it yourself with a hose.

[Mark]

You are correct, low freon can cause a PORTION of the indoor coil to freeze, the portion closest to the expansion valve. Low airflow on the indoor coil can cause the indoor coil to freeze.

But Low airflow on the outdoor coil will NOT cause the indoor coil to freeze.

Mark

[udarrell]

Wow! Guess I need to go into the condenser coil cleaning business.

If you can't get it thoroughly unblocked with a water hose, rent a power washer. Some even heat the water for you. It is always a good idea to use soft water. Never use detergents as many have an oil base the will insulate the fins!

With any pressure nozzle make sure the stream is straight with the fins or it will bend them!

- udarrell

[Stormin Mormon]

No, that does not sound possible. Clogged outdoor unit would warm up the indoor coil, not freeze it.

$375 for an exterior coil cleaning? Wow, I'm too cheap.

[Peter]

Probably. I just finished cleaning (DIY) an indoor ceiling mounted evaporator coil. The service mechanic wanted $500.00 for the job.

I did it with a hose, floor covering, bucket and about 3 cans of condenser coil cleaner. The finished result looked pretty good. Didn't even need a fin comb.

But another question... I need to purchase a vacumn pump for air conditioning repairs,,, probably both home and automotive.

Which size and quality vacumn pumps are used by the pro's ???

Thanks !!

Peter

[mm]

Of course this guy is not getting the job.

[Richard J Kinch]

You don't need a good vacuum if you rinse with refrigerant several times. (Assuming it's legal to vent, of course.)

[Richard J Kinch]

Could be a problem in your orifice (debris clog) or TXV (clog or unresponsive). Not a dirty condensor.

Condenser problems like that are easily diagnosed by playing a garden hose on it to temporarily improve the heat transfer.

[Al Moran]

Doh! Idiot.

[Stormin Mormon]

Would you suggest to take the fan off, and pressure wash from the inside, out?

[gm]

Thank you all for the replies; they pretty much confirm my suspicions that the freezing problem is not due to debris blocking the exterior fins/coils. Looks like I'll be getting a second opinion from another contractor.

[Robert Allison]

Do NOT use a pressure washer to clean the coil. You WILL bend the fins and then you will have a worse problem. Use a cleaning solution and a fin comb to clean and straighten the coil fins.

As to the original question, dirty fins outside will not cause the coil on the inside to freeze up. You are probably low on freon.