Over a year ago, I installed a White Rodgers demand defrost board (http://www.amazon.com/dp/B006JQ368W/ref=pe_385040_30332190_TE_3p_dp_1) because I was tired of the regular board defrosting unnecessarily. With the recent snowstorm here in southeast PA, we were not home, but I noticed my home's temperature was not maintaining. I figured there was an issue with the heat pump not being dug out. When I got home, it was of course iced over pretty bad. I dug it out and pulled the cover and as you would expect, all the lines inside were frosted over. The frost sensor from the demand board was still in place on the line going to the coils, but it would not kick into defrost. I currently have it defrosting manually, but I am wondering why this would occur? There was a good 1/4" of ice/snow on all sides of the unit, and with the lines being frosted, I figured it would kick in by itself. It's always been OK until this storm, so I don't quite understand what could be going on here.
Demand Defrost not working properly
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It was taking too long running in defrost mode, so I got the hot water hose. I did notice that the OAT sensor was sitting outside the unit lodged in some ice. Would this have any effect on it? I moved it back inside the unit around the wires behind the main panel, so it should get a pretty good air temp reading.
Also, the LED is solid red indicating there are no faults.
Also, the LED is solid red indicating there are no faults.
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Hopefully someone knowledgable will offer some troubleshooting steps for you but I assume there are no sensor fault codes? Are you terminating defrost at the default of 70, or something shorter? I actually installed a WR demand defrost board (47D01U-843) a couple weeks ago--thinking just like you--that I'd like to eliminate unnecessary defrosts but I have to be honest and say I wonder what will happen when we get significant freezing rain or snow. And I was in a little turmoil deciding where to place the coil sensor. My original sensor was just after the TXV, yet a couple installation videos show placing it on the lower coil.
With 1/4" of ice will a manual defrost actually remove it, or do you think you should unbury your outdoor faucet and hose and spray water on it, possibly removing the louvers if possible and possibly even removing the fan to access the inner coil. Obviously, just be careful so as to not hit nor bang on your system. Best of luck!
With 1/4" of ice will a manual defrost actually remove it, or do you think you should unbury your outdoor faucet and hose and spray water on it, possibly removing the louvers if possible and possibly even removing the fan to access the inner coil. Obviously, just be careful so as to not hit nor bang on your system. Best of luck!
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Ha - I type slower than you; you already answered part of that in your follow-up. As a side note, do you have any means of data logging to see at what intervals and time periods your unit has gone into defrost the last couple days?
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The OAT should be sitting outside the cabinet in the air (free of ice)
And yes... if the oat is covered in ice it will insulate it from the air temperature and cause faulty defrosting.
I do. I actually have an Allen Bradley PLC doing my home controls, and I was disappointed to learn that it had only spent a total of 238 seconds in defrost mode today, which was nothing!
Good to know about that OAT. I will try to relocate it underneath the unit where it gets good readings but won't become frozen.
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