Blockage in Coil


Old 05-12-03, 07:21 AM
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Blockage in Coil


I noticed a few days ago a severe icing problem at the outlet of my outside unit and the inlet to the coil of my inside unit. The outside unit is only 2 years old and the evaporator coil in the inside air handler unit was replaced ~ 4 years ago.

Anyway, I called a local service guy to check it. He thought it was low on refrigerant as his gauges indicated that. He added a few pounds of freon but was unable to get anything into the coil because it was still frozen. After a while he successfully unfroze the line, but he said his pressure was fluctuating widely which he thought indicated a plugged up coil and it would need replacing.

After he left, the unit was keeping up nicely with temperature and there was no longer any icing at either the outside or inside unit. I will get a second opinion on this, but my question is if the coil is "plugged" up, why is it now operating fine? Is this possible given the above indications and fixes? My feeling was the unit probably needed more time to completely thaw which was why the pressure was fluctuating so much, but I'm not sure. Any info anyone can provide is appreciated as I don't want to undrgo coil replacement unless I have no choice.

Thanks, all!
Old 05-12-03, 08:37 AM
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Hi Steve,

I'd get a 2nd opinion on it as well..

It's hard to give you an answer on here since we don't have our gage on the unit, and seeing what's happing.. I'd have this check soon to just make there's no damage being done to both section of the A/C system.
Old 05-12-03, 09:13 AM
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????????? Did he make sure that the inside A coil was clean , air filter was clean and the blower wheel was clean. That you had good air over the coil there before he pulled his gauges?Im with jay get someone else to look at it ED
Old 05-12-03, 06:05 PM
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you cannot charge a unit when it is frozen. if he tried to put refrigerant into the system before inspecting it for restrictions, coil, blower, filter, etc, do not call him again. he is no pro. it probably was low on refrigerant and after it thawed he was able to charge it. did he offer a leak detection service? has it run low before? what warranty do you have...many coils and condensers have 5 year all parts. if the leak is an one of these pieces of equipment you need to know, or that "freon pumper" will be billing you regularly!
Old 05-12-03, 08:38 PM
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HVAC4U is very very correct...step away from the unit. One does not add refrigerant without having the proper airflow going across the coil in the first place unless they enjoy the risk of damaging a compressor from overcharging or don't know what they are doing. There are a multitude of causes for units icing up and fluctuating pressures, such as faulty metering devices, breakdowns in filter/driers etc, in addition to being low on refrigerant, even though that is most likely the cause in your case.
Additionally, you really do need to find out why a unit as young as yours required the addition of refrigerant. Definitely call for a second opinion...and this time, be sure the second tech is experienced, licensed and certified to work on your unit.
Old 05-13-03, 06:44 AM
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Thank you all for the great input. Unfortunately I was not there at the time the service call was done, so I can't determine what steps he took. I do not think he visually investigated the coil. He did ask about the blower motor (I replaced it approximately 3 weeks ago). I suspected that could have caused a problem or it may be an unrelated incident.

I agree too the unit is pretty new to need a freon charge.
The filter was recently changed, so the only other issue may be something clogging the coil which I will inspect myself. I am scheduling a second opinion, as I am curious as to why this all occurred. When I replaced the motor, the AC had been running fine with no problems, but at the low speed. I changed the speed when I noticed the AC not keeping up with the temperature. Is it possible its running at the low speed did not move enough air and caused the freeze-up?

Thank you, again, for the wonderful advice. It is both helpful and educational.
Old 05-13-03, 07:04 AM
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Most definately low air flow can cause freeze-up.
My suggestion would be to ensure that the coil is completely defrosted and then get a new serviceperson to come to diagnose it.
Make sure you tell him/her the whole story as it could be overcharged.

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