Freezing evaporator - help troubleshooting please


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Old 07-08-14, 08:13 AM
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Freezing evaporator - help troubleshooting please

I have done some reading and looks like freezing could be restricted airflow or low freon/coolant whatever my system has. So.. Can someone give me a few poitners to check, before I call in a tech to recharge?

The issue is the evaporator coil is frozen frozen frozen. I turn on the AC unit, it works for a short amount of time, half hour maybe, while slowly freezing. By woks I mean cold air comes out the vents. After roughly half hour mark, the air stops coming out the vents. I look and see frozen evaporator at that point.

I checked the filter, but not real sure if its dirty/not. It looked fine. I shook/punched/banged the filter and some dirt and dust did shake off. Did not seem to help.

I do think the blower motor is going as I hear noise and air seems to be moving. However if there are any simple checks to be 100% certain that would be good to know.

There is water under the coil. It appears a drip pan of sorts is there and it is overflowing. I am not sure its due to thawing overwhelming the system, or a clog. Would this affect the cooling? Maybe a clogged pipe somewhere? What might be a good way to troubleshoot this?

The system is as follows:
Bryant Manufacturing
Model 300-511B
Serial 44W 11642 Series B

Images of frozen and image of coil to show dirty/not dirty are attached. Thanks for any help to troubleshoot.
 
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  #2  
Old 07-08-14, 08:21 AM
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I can't really tell from the pictures how clean/dirty the evaporator coil is, although it doesn't look particularly dirty. If you get a "normal" airflow through the system when the A/C isn't turned on (or rather the evaporator isn't frozen), then your airflow is probably sufficient, and it's likely low on refrigerant.

There should be piping, usually plastic, that drains the condensate (water) from the drip pan. It's not uncommon for the pipe to get blocked over time from "gunk" growing in it. You'll need to clean out the pipe. You can try applying vacuum to the open end of the pipe, or running a wire or snake through the pipe if you have a clean out opening in the pipe. The excess water in the drip pan won't cause the evaporator to freeze, however it should be taken care of.
 
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Old 07-08-14, 04:01 PM
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Very good news. AC has been running for hour or more now. Apparently, closing the vents in rooms I don't use caused a backup of air. Opening them made the air flow and stopped the freezing. Nothing wrong with my AC...
 
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Old 07-08-14, 04:27 PM
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Glad to hear that you solved your problem. The pros on here warn not to close too many ducts for just this reason, it restricts the airflow through the system and can result in the evaporator core icing over (as you found).
 
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Old 07-08-14, 05:10 PM
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i wish that was my problem for my evaporator freezing...
 
 

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