Inside unit coil frozen problem, plese help!


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Old 04-19-09, 09:58 PM
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Inside unit coil frozen problem, plese help!

Hi, everyone. Newbie and Dummy here. I have had inside unit frozen coil problem since last summer. It comes and goes. Whenever I heard noise from the inside unit without the sound from the blower, I know the coil is frozen. I then switch off the unit and wait for a couple of hours, the unit will back to work again if I switch it on.

Service guy came twice. He checked the temperature immediately after the compressor and it was OK (said not able to check Freon pressure because it was difficult to access the opening). Checked relay in both outside and inside unit, they seemed OK. These checkups were done when the unit was working, because whenever he came and switched on the unit, the unit would be working.

So he could not figure out the problem. He suggested me to change the fan motor. I also learn from the web that overheated motor would stop running. I feel not ready to spend the $400 plus as I doubt it would solve the problem, as I found out a way to get around and I would really like to figure out the reason first:

Now every time the temperature is high, I would turn on the blower first (by turning from auto to always-on), then turn on the A/C (from off to cool). This way the unit would be running fine. The blower would keep running for 8 hours without problem (longer time not tested), which makes me think the inside relay is not defect and the fan motor is fine.

Do you think this is a thermostat problem? Would you please suggest more test that I can do? I appreciate any input.
 
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Old 04-20-09, 04:49 AM
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Only two things will freeze a coil. Low air flow from a dirty coil/filter, Blocked air flow, or fan not running. 2nd thing is low on refrigerant.
 
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Old 04-20-09, 07:10 AM
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Thank you for your reply. The filter and coil are clean, and there is no blockage of air flow. I am pretty sure that the reason is that the fan failed to run, but do not know what to change. As I described, if I turn the fan to "always on" I do not have any problem. Only if I switch fan to "auto", frozen coil will occur at some point (within 1-4 days), not immediately. It seems at some points when the fan automatically switches off, it can not switch on again.
 
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Old 04-29-09, 05:05 PM
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if you have no auto fan in cooling check the configeration on the stat if you had it something ...is missing.if you get fan/on the relay boared is working that relay.
 
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Old 04-30-09, 10:14 AM
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Frozen coil/Leaking unit

I seem to have a similar problem with my Gibson home A/C unit. The unit came on but you could not feel any air coming out of the vents. Noticed the fan was coming on outside but checked upstairs in the attic and discovered a section of the unit was frozen. I changed the filter, then turned the unit to fan and left it on, set at 70 degrees to melt the ice. The ice melted into the pan but no air came out of the vents still.

I had an A/C tech check it out and he indicated the evaporator coil is leaking freon and it has caused the coolant level to drop, which caused the unit to build ice. He wants to replace the coil and refill the coolant. He indicates the evaporator coil is still under warranty so it would be free to replace, but he will charge $600 for the evaporator coil replacement labor and $200 to refill the coolant.

First time home owner, so don't know much about this stuff. Does all of this sound about right to you?
 
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Old 04-30-09, 10:47 AM
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The Pro's will be around...but I don't think thats excessive..IF the coils are the real problem.

How did he find the leak..did he use an electronic sniffer of some sort? Did he put dye in the system? OR was he just guessing? Did he hook up gauges and test pressures?

If you didn't get any air..there still must be a problem..clogged coil or something. Its possible a good cleaning would fix it. You should turn the system completely off for a few hours to let the ice melt..then just turn the fan on and see if you get airflow.
 
 

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