AR15.Com Archives
 My Central Air A/C Unit Keeps Freezing Up. How Come?
mk1iii  [Member]
6/29/2005 9:56:13 PM
It didn't start doing untill this year. I have it set to cool down to only 71 and after a few hours the line running from the outside condenser into the house freezes up. It'll be blowing air out the seems of the unit in the basement but not throughout the house and it's not that air isn't really cool either.

Once I shut it off for a better part of the day it's good to go again until it happens again. Sometimes a day, maybe a couple of days.

Any ideas? Condensate line blocked? How would I fix that if it was? Something else?

Thank you for any advice you may offer.

Mark
MikeTx  [Member]
6/29/2005 9:59:30 PM
The condenser is dirty and needs to be cleaned out. That's the thing with the fins real close together.
The_Camp_Ninja  [Team Member]
6/29/2005 10:01:48 PM
Also, something as simple as a dirty air filter will do this thing you speak of.
Only_Hits_Count  [Member]
6/29/2005 10:02:27 PM
"Only 71" !!!!???

try it on 78ish..

my guess would be low freon.
WildBoar  [Team Member]
6/29/2005 10:03:13 PM
clean filter, clean the coils, check pressure make sure airflow in your house is not restricted( wont really effect freezing but good to do anyway)
fxntime  [Team Member]
6/29/2005 10:07:10 PM
Originally Posted By The_Camp_Ninja:
Also, something as simple as a dirty air filter will do this thing you speak of.
[/quote
] First place I'd look also. Then the condenser, you can get a coil cleaner that will help immensely for that. If at all possible, hose it from the inside out. If no go then check the hi and lo side pressures and see if it's low on freon. [Bout this time you will need to call an A/C guy]My 25 year old A/C still works perfectly and puts out 58 or so degree air. A little TLC goes a long way with A/Cs.
cjklekar  [Member]
6/29/2005 10:09:46 PM
From my experience w/ mobile A/C units...freezing up is an indicator of low freon...dichlorodifluoromethane...
viper5194  [Team Member]
6/29/2005 10:13:05 PM
Mine froze up last year one time, checked the filter it was dirty as hell... changed it and it worked for the rest of the summer. This year it froze up again, checked it and again it was a dirty air filter. The coil requires air passing over it to keep from freezing. To defrost it faster, remove the filter and turn the fan on only, without the ac.. Itll defrost in about 2 hours........ If its low on freon itll freeze up as well but id place my money on the filter....
jrzy  [Team Member]
6/29/2005 10:16:43 PM

Originally Posted By viper5194:
Mine froze up last year one time, checked the filter it was dirty as hell... changed it and it worked for the rest of the summer. This year it froze up again, checked it and again it was a dirty air filter. The coil requires air passing over it to keep from freezing. To defrost it faster, remove the filter and turn the fan on only, without the ac.. Itll defrost in about 2 hours........ If its low on freon itll freeze up as well but id place my money on the filter....



Yep the HVAC guy told me that when he put in the AC units in the new house.
He said not enough return air flow will freeze the units up.
DrMark  [Team Member]
6/29/2005 10:16:45 PM


This recently hapened to me. My brother-in-law in the business said primary causes are restricted airflow (e.g. clogged filters) or low refridgerant levels. My filters were fine so I called service. Refridgerant was low, he charged it, and it's been working fine.

bear3351  [Team Member]
6/29/2005 10:19:20 PM
I had that problem a couple of years ago, check the return air ducts, make sure they are not blocked, you may need to open/install another return.

Also check that that the water that is collected somewhere in the unit can get out, that was my problem! somehow I removed a pvc pipe that was attached to the unit (in the basement) and it was clogged. I replaced the pipe and problem solved.
aerod1  [Member]
6/29/2005 10:23:16 PM
If your unit was low on refrigerant you probably have a leak, which needs to be repaired. If not you will be doing this again. Just "topping off" the charge is only a band aid.
freemanesq  [Member]
6/29/2005 10:59:17 PM

Originally Posted By cjklekar:
From my experience w/ mobile A/C units...freezing up is an indicator of low freon...dichlorodifluoromethane...



Agreed. We just did this at my house (I hope it's your return air). The low level of freon allows it to uncondense (what ever that word is) before it gets to the exchange in the house.

R.
fight4yourrights  [Team Member]
6/29/2005 11:01:50 PM
Defrost cycle isn't working
KEA  [Member]
6/29/2005 11:04:53 PM
I had clean filters & kept the coils relatively clean for 6 years when mine started this. Finally pulled the drum fan out and found the 'cupped' blades were more like round rods - full of hard dirt - which didn't push much air. Cleaned them out and everthing went back to normal for a couple of more years.
MC_Man  [Team Member]
6/29/2005 11:05:23 PM

Originally Posted By cjklekar:
From my experience w/ mobile A/C units...freezing up is an indicator of low freon...dichlorodifluoromethane...



That's R12, used in older automobiles, and now basically outlawed. Chlorodifluoromethane is R22, commonly used in home AC units. Or maybe mobile units use R12... I could be wrong.
Troy  [Site Staff]
6/30/2005 2:02:31 AM
Another cause for freezing is if the insulation (usually foam) on the line to the unit has been damaged or removed. Without the insulation, the line will freeze. My dog ate mine once.

-Troy
k9dpd  [Team Member]
6/30/2005 2:09:32 AM
mine did this at the start of the AC year and the problem was the outside temp was cooler than 71 and it caused it to freeze up, now the the outside temp stays above 71 we have no problems
mk1iii  [Member]
7/1/2005 8:46:54 AM

Originally Posted By fight4yourrights:
Defrost cycle isn't working



Gee F4YR, I never thought of that.

Thank you guys. I changed the filter and it hasn't done it again yet. The insulation has started to break up around the pipe coming into the house so that may have contributed as well.

Appreciated it!

Mark
jcncc  [Member]
7/1/2005 9:02:05 AM
Low Freon
fight4yourrights  [Team Member]
7/1/2005 12:58:25 PM

Originally Posted By mk1iii:

Originally Posted By fight4yourrights:
Defrost cycle isn't working



Gee F4YR, I never thought of that.

Thank you guys. I changed the filter and it hasn't done it again yet. The insulation has started to break up around the pipe coming into the house so that may have contributed as well.

Appreciated it!

Mark




Well if the defrost were working, you wouldn't have it freezing up.