[Val97]

Hello I have a 12 year old heat pump system and am currently running my furnace on E-heat which should bypass the heat pump however this morning my air conditioning machine kicked on and the fan would not turn off. I turned the thermostat off and the fan still ran until I pulled the main switch. The furnace is still running on e-heat. What could be wrong with my heat pump/air conditioner?

 

[Bitters]

Have you recently replaced the stat?

 

[Val97]

No The stat is the same age as the units

 

[beenthere]

Might have a short in the low voltage wiring.

 

[Val97]

At the thermostat circuit board or a circuit board within the furnace?
Thanks so much for the replies

 

[Bitters]

I would check the stat wires in the furnace first. Then check the stat wires outside, make sure no critters have been chewing on them.

 

[DOUG1111]

At the thermostat circuit board or a circuit board within the furnace?
Thanks so much for the replies

I would look close-with power off @the control board @ the furnace- Look both sides for burnt spot - When in E-heat does the fan cycle off?? Pics-control board :vs_worry: Be careful of electric!!! AMP draw on the blower mtr?? Info of AMP draw is on the mtr.-- 24VAC short- check the T/S wires inside & out, may be short to metal?

 

[supers05]

I'm also thinking a short somewhere. Model numbers of the indoor/outdoor units will be helpful

Cheers!

 

[DOUG1111]

What was the fix??????

 

[Val97]

The furnace is a Lennox Merritt Seies
Series G40UH(X)
Air conditioner/ heat pump - Lennox 10HPB series

There does not appear to be anything chewed on as far as wires.

The control board was replaced last year

Thanks for all of your replies!!

 

[supers05]

That model is coming up as a gas furnace. (g40uh) Please confirm. If it is, you should have a fuel conversation board somewhere.

Cheers!

 

[Val97]

Yes it is a gas furnace and that is the model.

 

[DOUG1111]

The furnace is a Lennox Merritt Seies
Series G40UH(X)
Air conditioner/ heat pump - Lennox 10HPB series

There does not appear to be anything chewed on as far as wires.

The control board was replaced last year

Thanks for all of your replies!!

What was the reason the control board was replaced last year????? Did you look @ the board both sides???

 

[Val97]

The board was replaced because the furnace would come on and turn off in just a few seconds. I have attempted to attach a picture of the board. There do not appear to be any burnt spots

 

[Val97]

The thermostat was on E-heat but yet the heat pump kicked on... I heard a noise outside that sounded like the compressor I went outside and saw the fan running
which made no sense since I am running e-heat. I came inside and switched the thermostat to the off position and the fan still continued to run. I had to go back out to the air conditioner and turn off the heat pump at the main on the outside of the house. The furnace is still operating fine on e-heat and I have just kept the switch off at the main outside to the heat pump.

 

[beenthere]

Contactor in heat pump may be stuck or burnt closed.

 

[DOUG1111]

Contactor in heat pump may be stuck or burnt closed.

^^Yes I agree! ^^^^ Sorry I thought we were talking about the inside blower staying on. Do you know what a contactor is?????

 

[Val97]

Yes and it is burnt but what would all the sudden one day signal that electromagnet when I am running on emergency heat ?

 

[DOUG1111]

Yes and it is burnt but what would all the sudden one day signal that electromagnet when I am running on emergency heat ?

The outside fan mtr is plugged into the defrost control board-- is the board getting a call from T/S???

 

[beenthere]

Could have a short in the low voltage wires to it.