Heat Pumps and Electric Heating - Heat pump, Aux lite on, air cold!

Now I have another problem. Outside temperature 40 degrees. RUDD system.
The AUX (green light) comes on but the air from the registers starts running very cool to cold. If I shout off the heat at the thermostat then back on several times fast, the register air will start to warm up and the AUX lite go's off. Sometime during the night or early morning it will do the same thing again and I have to repeat the shut off/on procedure.
Is this the reversing valve sticking or is there another possibility?
Changeling

PS. The thermostat is about 15 years old. What is the best thermostat going?

Does kind of sound like the r/v sticking or could be the stat not sending the signal through the "O" wire.

When it's blowing the cold to cool air, go out and check the outdoor unit and see if it's blowing warm air and what the copper lines feel like.

On most units the R/V should fail in heat are like is always in heat mode. Its only when you go to AC or defrost that the valve should have to work.

ED ;)

I was thinking Rheem/Ruud was backards.

On most units the R/V should fail in heat are like is always in heat mode. Its only when you go to AC or defrost that the valve should have to work.

ED ;)

Hi Ed, I don't know how to decipher what you said. Can you please elaborate a little more. Can it be the Thermostat or is it definately the R/V?
Thanks, Changeling

The reversing valve on most units is in heat mod all the time. Like they say if it fails you can get heat if you need it. Now when you go to AC or defrost then the valve should work or open. That way the liquid freon goes into the indoor coil to cool it when it goes to a gas there. Lets try this. Turn the tstat to heat and push it up. Does the big copper line get hot???? Now turn the tstat to AC and push it down. Does the big copper line get cold and wet???? This should tell you if it works or not.


ED ;)

The reversing valve on most units is in heat mod all the time. Like they say if it fails you can get heat if you need it. Now when you go to AC or defrost then the valve should work or open. That way the liquid freon goes into the indoor coil to cool it when it goes to a gas there. Lets try this. Turn the tstat to heat and push it up. Does the big copper line get hot???? Now turn the tstat to AC and push it down. Does the big copper line get cold and wet???? This should tell you if it works or not.


ED ;)

Ed, I will follow your instructions to the letter! How long should I wait between each sequence, Hot and Cold?
Sorry it's that dam analytical mind of mine tripping in. The last time this happened they said it was the R/V, and it cost me about $600.00 for them to fix!
Changeling

Just 5 --10 minutes

ED

I went through this same thing last winter with my brand new heat pump. It kept blowing out cool air and ran all the time because the thermostat was never satisfied with the desired temperature. After I finally got the builder to send his HVAC guys out, they realized that my reversing valve was stuck on the A/C mode and that was the problem. When you are in heat pump mode, the copper piping outside should be hot, and when you are in A/C mode, the piping should be cold. I also ended up having a crack in my coils and was leaking freon but that's another story in itself. Good luck and I hope everything works out for you. Jim :)

Ed, I performed the tests as you directed. In heat mode it's hot, in air mode it's cold.
Keep in mind that the problem I described doesn't happen everythime the heat comes on. just 2 or 3 times a day/night. :wall:
Changeling

That tell us the RV does work. So like Matt said the next time it just blowes cold air and is calling for heat. Check the out door unit. See if its running and in heat or cool. feel the big copper line.

ED ;)

That tell us the RV does work. So like Matt said the next time it just blowes cold air and is calling for heat. Check the out door unit. See if its running and in heat or cool. feel the big copper line.

ED ;)

I will do exactly as you suggest and let you know. It didn't do it yesterday or last night, that I know of.
Changeling

That tell us the RV does work. So like Matt said the next time it just blowes cold air and is calling for heat. Check the out door unit. See if its running and in heat or cool. feel the big copper line.

ED ;)

Ed , A "Distant" neighbor that i talked to today said it could possibly be the "Thermostat" and I should check it out, "Whatever", I pulled the cover off and the 'Mercury" filled vials and everything else was "Encrusted" with dust to the point that the top of the vials appeared to have a light covering of snow on them!! This can't be right!
There is one vial on top of another separated by about 1.75 inches and these are directly related to a spring !
It is extremely sensitive to "touching" so i don't know exactly how to clean it so i figured I would check with you first!
Can I just spray it with contact cleaner or is this dangerous ?

I know you had asked Ed but for what it's worth here's my two cents worth. Turn the thermostat "Off", turn the temperature setting all the way one way or the other, take the canned air you use on the keyboard & have at it. Stay far enough back so you don't blast the thermostat. I prefer the air or nitrogen to the 3M dust remover since it is actually a refrigerant (R-134A, the same stuff as is in your car A/C).

Hi Grady. I tried the compressed air , it just blew off the loose dust. The vials are still encrusted. I guess through the years some cooking oil in the air or whatever got on them with the dust. I'm going to take some swabs like you clean you ear with and use some alcohol to clean them.

Grady, can you recommend a really good replacement thermostat? This one is over 20 years old so maybe it should be replaced.
I understand they have some digital ones now, I don't think they work off the mercury filled vials, but not sure.

For your heat pump there dont mess with a programmable one on the heat pump. What you save on set back it cost you on the pick up. Cause the strip heaters cut in. Might look at a honeywell T841A

ED ;)

Hello Ed. I cleaned the vials, spring, everything this morning with the swabs and alcohol. So far it has definitely made a difference in the heat not popping on and off so much. its about 32 to 35 degrees out side and I haven't seen the Aux heat light yet! However, we are only talking a few hours so far. I hope that tonight "Murphy's Law" doesn't kick in and everything falls to hell again.
I have not experienced any more of the "Aux Lite on" and cold air either since I complained about it. However I received my electricity bill for the last 29 days. Keep in mind I'm single, use washing machine and dryer once a week at most and keep the thermostat on 72 degrees!
Crap, when i went to check what I keep the thermostat at the Aux lite was on, it is 38-39 degrees outside, I switched it on and off several times, now it's running without the Aux lite on!!!!
The electric bill by the way says I used 3055 KWH in the last 29 days ($199.00 this month)!
Ed, what in the Hell is going on? :wall: