Window air conditioner freezing up

[Gary_in_Indiana]

Tonight, for the second time this spring, a large window air conditioner I use in a shop office has frozen up. By "frozen up" I mean that it has developed frost and then solid ice on the fin area on the inside while it's still running.

It has been incredibly humid here today with all of the rain we've had combined with temperature highs near ninety again today.

I actually seem to recall encountering this problem many years ago on a different AC in a different property but have no recollection of what solution I implemented. Can anyone refresh my memory on this one? I turned fifty this week and the memory isn't what it used to be. /forums/images/graemlins/wink.gif Thanks.

 

[Cliff_Johns]

Oddly enough, I think air conditioners freeze up when they are low on Freon.

Sounds backwards, but I think it works that way.

Cliff

 

[Egon]

Iced up condensor fins is a commom problem on hot humid days. This usually happens to Ac units that are on their highest cool setting and may be undersized for the service conditions they are placed in.

Set the air conditioner at a very low cool setting and then slowly ramp it up till you find the point at which the condenser begins to accumulate ice drops. Then back off on the cold setting. This will keep the unit running efficiently. It may take longer to cool down the area. As soon as ice forms might as well turn it off and wait for all the ice to melt as the init can not work properly.

Egon

 

[Bird]

I agree with both the other guys. Egon's suggestion will help, but like Cliff, the only time I've had that happen was when the unit was low on freon. In fact, it happened to my central A/C unit late last summer (9/14/03). I got up one morning, noticed it was running but not moving any air, didn't sound exactly right, found the evaporator coils completely iced over, shut it off, and it took over 4 hours for it to all melt off. That evening, I had freon added and have had no more problem. However, since it's 7 years old, I've been wondering whether I'd have the same problem later this summer.

Egon, I always have to stop and think about which is which, but I think it's the evaporator coils that ice up instead of the condenser, isn't it?

 

[MikePA]

<font color="blue"> This usually happens to Ac units that are on their highest cool setting and may be undersized for the service conditions they are placed in.</font>
A unit that's low on freon would be undersized for the service conditions. Everyone is correct! /forums/images/graemlins/cool.gif /forums/images/graemlins/grin.gif

 

[Gary_in_Indiana]

<font color="blue"> "Everyone is correct!" </font>

Even me? /forums/images/graemlins/smile.gif Maybe the reason I don't remember doing anything to fix the problem is because I just shut it off and, when I tired to use it the next time, it worked so I never really DID anything. /forums/images/graemlins/wink.gif /forums/images/graemlins/smile.gif /forums/images/graemlins/grin.gif

 

[PineRidge]

A couple of reasons that an evaporator on a window air conditioner might freeze the condensate:

unit filter plugged or restricted,
unit evaporator coil restricted or dirty,
ambient temperature too low, (no load on equipment)
unit thermostat setpoint too low.
unit low on feon,

Check that filter and make sure the coils are clean. Good luck to you! /forums/images/graemlins/grin.gif

 

[Egon]

It's one or the other Bird. The evaporator would sound like the right one.

Seems with my small size seven feet I always one or two of them in my mouth!!!

Egon /forums/images/graemlins/tongue.gif

 

[bgott]

Slide it out of the case and run it outside and wash the coils. They sell an acid for cleaning coils at an A/C supply house. Clean the condenser while you're at it. The blades on the squirrel cage fan might need a good cleaning while you're at it. I used to pick up window A/Cs off of the side of the road and clean them. Most of them would last another year or two in my rentals. If they spring a refrigerant leak they are usually not worth fixing. Most window A/Cs these days use secondary cooling on the condenser coils. That means they let the condensate off of the evaporator coil puddle up under the condenser fan and get blown over the condenser rather than drain out a hole in the bottom of the unit. It helps the unit work really well but also rots the fins and tubes out of the condenser. You don't see this until you open the unit up for cleaning or service and look at the inside.

 

[fractal]

Uhmm. Ok, guess I am the odd guy out.

I heard that air conditioners "ice up" when they are OVERSIZED. Seems they need to run long enough to get up to heat. If they are oversized, they run a short time, get the room cold, and shut down.

Course, I could be remembering wrong. Either way, the problem is your AC is not properly matched to the place you are trying to cool. There are plenty of calculators out there to help you determine how many BTU's you need given your sq ft, facing, windows and insulation. Too big or too small are both bad.