Auto Switch-over From Heat Pump to Furnace

[Madrona]

I have a 2003 Itasca Horizon 32TD with the basment heat pump. The way it is supposed to work, and has always worked, is you set a temp at the One Place panel and select Electric Heat. If the heat pump can work (above 36 degrees, I believe) it does, if not, because it's colder, the gas furnace kicks in.

We keep the coach plugged in at home via 120 volt 12g extension cord. I select 20 amps at the panel and half the heat pump works. However, I found yesterday, only the furnace is coming on, not the heat pump. I tried everything I can think of but no luck.

I disconnected the coach from power, waited and plugged back in. I turned off the heat entirely and turned back on. I checked the breakers, turned each off and back on. No luck. The heat pump DOES work if I choose Cool and lower the temperature setting on the One Place thermostat.

I opened the door to the heat pump and removed the electrical panel cover. I was looking for a fuse but didn't find one. There is one green light glowing on the panel.

Where should I look next?

[Wizard]

Check the 12 volt circuit breakers, though I doubt thats it cause the furnace uses 12v also, past that I'll leave it to the experts. The t'stat runs off 12v.

[jettyjock]

normally electric heat means strip heaters, or sometimes called emergency heat. If you have strip heaters there should be a seperate circuit breaker for it. A heat pump has a valve, when put in heat mode makes the freon bo backwards from cooling mode. When it comes on you will hear the valve shifting.

[ernieh]

What happens when you try to run the AC/Heat on the generator?

I keep my unit plugged in to a 20a circuit in my garage and that power supply is marginal for any of the higher draws. You may have fried something due to low voltage.

[CC38EL]

This sounds like your reversing valve is stuck or broken in the cool only position. When mine does that, I run it in cool mode for a while....then turn off the whole thing at the thermostat.

I flip the circuit breakers, wait about 5 minutes, then turn every thing back on. Select electric heat and it starts working.

If yours doesn't you may need to open it up to see if the valve is fried.

[Meurigd]

Strangely enough, I've got a similar problem with my '07 Meridian, except the heat pump will not switch on at all, for either heating or cooling. Just happened today. I suspect my problem is electrical, probably a breaker somewhere. I've flipped the breakers at the panel at the foot of the bed, but are there any heat pump breakers in that panel at the rear of the coach in the shore power input compartment that I need to get to for this problem ?
The gas furnace works fine, but the circulating fan does not even come on when the switch is in the elec position.
Sorry to interrupt the post, but my problem is so similar I did not think that I should start a new topic. (I've got the dash pulled apart to work on the radio at the moment, so I have not had a chance yet to get stuck into the heat pump thing).
Thanks for any help
Meurig Davies 2007 Meridian 36G

[Madrona]

Originally Posted by ua40j

This sounds like your reversing valve is stuck or broken in the cool only position. When mine does that, I run it in cool mode for a while....then turn off the whole thing at the thermostat.

I flip the circuit breakers, wait about 5 minutes, then turn every thing back on. Select electric heat and it starts working.

If yours doesn't you may need to open it up to see if the valve is fried.

Thanks, Jim, I'll give that a try. We have had storm after storm here. This problem started after a windstorm that knocked out the power a couple nights ago. The power was off, on, off, on, off, on then off for a day. Might have knocked out some electronic component, I suppose...

[DancinCampers]

The following quoted from my service manual, trouble shooting section:

No Heating: Electric Mode
(Green LED Light Circuit)
F/FY Circuit Open to the T-stat

Rare occasions have occured where the green LED light is ON and the F/FY circuit is open, thus preventing compressor operation. To verify this possibility, temporarily bridge across the F & FY terminals at the t-stat or at the PC Board. Replace the board if the green light is ON and the jumper completes the open circuit initiating compressor operation.

[Madrona]

Originally Posted by ernieh

What happens when you try to run the AC/Heat on the generator?

I keep my unit plugged in to a 20a circuit in my garage and that power supply is marginal for any of the higher draws. You may have fried something due to low voltage.

I did start the generator thinking that maybe more juice would make the difference. It didn't. Furnace starts first, the heat pump doesn't start at all when on heat. Maybe it was all the electrical surges that started and stopped multiple times during our storms. "Fried something" is what I'm thinking....

[Madrona]

Originally Posted by DancinCampers

The following quoted from my service manual, trouble shooting section:

No Heating: Electric Mode
(Green LED Light Circuit)
F/FY Circuit Open to the T-stat

Rare occasions have occured where the green LED light is ON and the F/FY circuit is open, thus preventing compressor operation. To verify this possibility, temporarily bridge across the F & FY terminals at the t-stat or at the PC Board. Replace the board if the green light is ON and the jumper completes the open circuit initiating compressor operation.

Thanks, Dan, that gives me a place to start. Dang, there are a lot of wires, etc. on and around that board. It's gonna be crowded getting in there. I'll jump it at the thermostat but I bet your troubleshooting is correct and that board needs to be replaced...

[two2go]

If you have more than 4 deg. between the thermostat air temperature and the set temperature, the furnace will come on rather than the heat pump. That's the way my unit works, anyway. I'm also surprised your unit will run on 20 amps. Mine won't unless I'm on 30 amps minimum.

[Madrona]

Originally Posted by two2go

If you have more than 4 deg. between the thermostat air temperature and the set temperature, the furnace will come on rather than the heat pump. That's the way my unit works, anyway. I'm also surprised your unit will run on 20 amps. Mine won't unless I'm on 30 amps minimum.

Hmmmm.... Not really sure if there were 4 degrees difference or not. I'll check that out, good info, thanks! I was surprised mine ran also, but it has done it for months. It is a 12g cord, but even so, I was surprised. I just hate eating up all my propane!

[rvGator]

I agree with two2go. It fix my problem last winter.

[Hikerdogs]

Originally Posted by two2go

If you have more than 4 deg. between the thermostat air temperature and the set temperature, the furnace will come on rather than the heat pump. That's the way my unit works, anyway. I'm also surprised your unit will run on 20 amps. Mine won't unless I'm on 30 amps minimum.

That's the way ours works as well. Another thing that may be happening is that your temperature sensor may not allow the heat pump to operate down to 36*. Ours usually won't work below 38*. Some people we travel with can't get theirs to work below 40* while, others canget theirs to work down to 34*. 36* may be the average temperature that the heat pump is locked out, but by no means is it the absolute temperature.

[ernieh]

Originally Posted by two2go

If you have more than 4 deg. between the thermostat air temperature and the set temperature, the furnace will come on rather than the heat pump. That's the way my unit works, anyway. I'm also surprised your unit will run on 20 amps. Mine won't unless I'm on 30 amps minimum.

On mine, and I'm pretty sure yours also, heat pump AND furnace will come on if more than 4 degrees of rise are called for.

[Hikerdogs]

Originally Posted by ernieh

On mine, and I'm pretty sure yours also, heat pump AND furnace will come on if more than 4 degrees of rise are called for.

That's true, but if the outside temperature is below the minimum the sensor will allow the heat pump to work only the gas furnace will run.

[Martind4]

Our coach is a little older than the 2003 model and we have a red reset button in electrical box of our basement air. If you have problems with intermittent power, the compressor might have kicked out on high pressure. Here is a pic of the reset button in the upper right. Newer coaches don't have this reset button.

[two2go]

Originally Posted by ernieh

On mine, and I'm pretty sure yours also, heat pump AND furnace will come on if more than 4 degrees of rise are called for.

Winnebago applications may be different. On my Dolphin according to the manual and in practice, if the heat pump cannot satisfy the thermostat call (more than 4 deg. inside difference or below 38 deg. outside), the gas furnace becomes the primary heat source and the heat pump is locked out. There is a counter in the logic board, and if the call is bypassed to the furnace three times in succession, the heat pump is locked out for 2 hours. That is unlikely because the inside temperature would have to continue to drop while the heat pump is running.

In practice, I jump out of bed on a cold morning and set the thermostat carefully not more than 4 degrees above the indicated temp. and the heat pump comes on. Since the unit is under the bed, the cat panics and jumps off which wakes the DW who starts cursing me both for the cat jumping off her and the noise of the A/C unit under her. I ignore both, make coffee, and keep tweaking the thermostat up to maintain a 4 deg. separation until the desired room temp is achieved. Once both of us have had our coffee and the cat has had her kibbles, peace is restored and all is well until the next morning. I do this to conserve propane, and because I can.

[DancinCampers]

I have added a switch on the pigtail to the LP furnace from the t-stat, which allows me to raise the set point without the gas furnace ever coming on. Originally installed to keep our bikes safe, our furnace is right above our hitch.

[Wizard]

In real cold weather we use cube heater sitting on the table in the kitchen. Let whatever else help it out.