coil iced up, but not defrost board, dirty coil, or low freon

10 years ago

I had pretty technicians from a prestigious HVAC company coming twice to check why the heat pump coil outside iced up. First time with the first guy said that my freon was low, so he added it. I worked slightly better but the coil still iced up within a week. I called the company back, and they sent two different guys here. They said that the defrost board was bad.

I ordered the board and replaced it myself and used the hose with the spraying nozzle to clean the coil without dissembling anything (spraying the water directly through the slotted panels of the cage). Then air came out still cool yet it was "slightly" warmer than before with the old control board and uncleaned coil. It took about one or two hours for the unit to work properly (meaning: sending out warm air). I am not sure if the outdoor temperature did the trick or not. It was a good mid day about 50 degree.

This morning was about 29 degree outside. The unit kept working hard for 3 hours but only did 2 degree rise . The air sent out from the vent felt only slightly warmer than the room temperature. I had thought that the problem solved yesterday after my feeling the warm air out of the vent. This morning I checked the heat pump, and as I suspected it, it was iced up again.

I literally used pliers pulling out all the pine straws and leaves stuck between the coil and the slotted panels and hosed them down. Actually the unit was not dirty at all due to no trees or shrubs surroundings. There weren't many straws or leaves to clean up. I would suspect that the coil still too dirty to work right.

I have read articles about iced up coil, and low refrigerant, dirty coil, and malfunction of defrost board seem to be the only 3 reasons for icing up coils......WHat can I do now? Please help.....

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Comments (4)

klem1
10 years ago
The louvered panels need to be removed while cleaning coils. Water must be sprayed in opposite direction to normal air travel. If that requires removal of additional panels or motor,it's still nessary if coils are to be cleaned. Spraying water in same direction as air flow drives trash deeper into coils. When you say there are no trees or shrubs,that's only one source of trash. Weeds and grass contrubite lots of coil clogging material as do several tree species blocks away.
SpecialtyAirInc
10 years ago
I agree. You should clean it thoroughly. Also, take care not to go any deep if you cannot fix it. You might want to use a coil foaming cleaner.
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chueh
Original Author
10 years ago
Thanks both. OK... would you mind explaining to me how to determine the direction of NORMAL AIR TRAVEL. Is it the same way as the fan blades travel??? I just sprayed water from inside (not really inside, but just tilt the hose in an angle to spray the water outwards). I thought that this way the dirt or grime would be pushed outward.

By the way, I was actually trying to take the panels off, starting the top first. However, the fan was attached to the top penal and there was a cord attached to...that's why i gave up. I am just a 120 pound female..... :-) However, my hubby can help me at least hold the top panel up for me to lose up any attachment. How do we do that??? Without being disassembled on the top, the side panels cannot be disassembled either.
klem1
10 years ago
My bad but disassembly is usualy obivous to those who get involved with this type stuff. Due to the hundreds of different configurations,it's not possible to give step by step but here's an overview. Make certain electric power is off to unit. Assuming fan is facing up,air enters from exterior of sides so water must enter from inside and exit to outside. The idea is to push debris back to the direction it ame from. Most techs label and disconnect wires then remove top along with motor and set it aside until finished. If side panels can then be removed,that helps. Believe it or not,that's about all that can be said because normaly,the first time one sees it done they are only watching or teacher is standing behind them. Look at it this way. If your employer hired you a helper while you were on vacation,could you write down and mail a note telling them how to do the job which they have no experience with? Baby steps need to be taken before diving all the way in. Good luck