Heat pump strangeness

Discussion in 'Shop Talk' started by WanderingOak, Apr 7, 2005.

  1. WanderingOak

    WanderingOak Well-Known Member

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    Yesterday was the first day that it was warm enough to turn on the air-conditioning. When I switched the thermostat over from heat to cool, the gas furnace (backup heat) came on, rather than the air conditioning. I tried several times, at different thermostat settings, and no matter what I did, the furnace fired up. I switched off the furnace at the breaker, and now the thermostat might as well not be there, because it doesn't do anything. I can't even get the blower to come on without the furncace. I am hoping that this is a thermostat problem, because I really don't know what else would cause this problem. Does anybody out there have any insight?
     
  2. farminghandyman

    farminghandyman Well-Known Member Supporter

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    the only thing that comes to mind is the possiblity of the wires being mouse chewed and shorting out, and engerizing the wrong system.

    or a relay stuck but when you switch it over you should be using a diffrent set of wires or at a differnt pair of the wires to the thermostate

    QUestion has the heat pump been working on the heating cycle of the heat pump,? has the AC/heat pump compressor and system been working right up to this time?
     

  3. WanderingOak

    WanderingOak Well-Known Member

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    Now that I have been thinking about it, I have not heard the comperssor part of the heat pump cycle at all for a while. My gas bill has been a bit high of late, so the compressor taking a lunch break could be the cause. I see a large repair bill in my future :rolleyes: , especially since I plan on selling the house soon. I'm not a HVAC tech, so I don't have the tools to even think about working on this myself.
     
  4. farminghandyman

    farminghandyman Well-Known Member Supporter

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    I would sugest you call in a good heating/AC repair person that you trust, or one that comes highly recomended,

    It may be some thing simple in the control box or a wiring problem or relay, because even if the AC unit was not working, the furance should not be coming on, in the cooling mode.

    it could be as simple as a lose wire that is shorting out two terminals and making the furance the only working unit of the system,

    but if you have little knowledge of the systems find some one who does, it may save you more money in the long run,
     
  5. WanderingOak

    WanderingOak Well-Known Member

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    I've got somebody coming over this afternoon. I did find a wiring access pannel open in the crawl-space a few weeks ago. It might have something to do with this problem, and it might not. My A/C is at least five years old (came with the house), so it might be a good idea to get a newer system before selling. I definitely want it working before I put it on the market.
     
  6. 2story

    2story Well-Known Member

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    the average life of a HP is 15 year's. It sound like a cheap fix, compared to replacing!
     
  7. WanderingOak

    WanderingOak Well-Known Member

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    I paid $75.00 for a service call to be told that the problem was in the external thermostat. The t-stat was faulty, which didn't let the heat pump function. All that was working was the gas powered emergency heat (which also cuts in below 20 degrees). He turned the t-stat down to 0 degrees, so now the heat pump works again. It won't automaticly switch over to gas power at low termerautres, so lets just hope that it stays above 30 degrees until I get this fixed. Or course, he didn't have a thermostat in his truck, although he said it takes about 5 minutes to replace- just three color coded wires and two mounting screws. If I knew what I was doing, I could have figured this out on my own. I wonder how much propane I wasted while this thing was malfunctioning.
     
  8. farminghandyman

    farminghandyman Well-Known Member Supporter

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    yes I know the feeling, ( we had ours freezing up, and i checked out what I thought was ever thing and come to the conclusion it must be low on charge, they come out and we have a life time filter and it was washed and cleaned ever week, but over the years it slowly plugged up, not letting the air flow, DID I ever feel stupid, $80 for having them come out and wash out the filter with a garden hose, we were washing it in the shower with a hand held unit, and not using enough pressure or flow to wash it out completely,)

    but look at it this way, the $75 and the thermostat is much cheaper than a new heat pump, and my guess is $2000 for a new heat pump.
    The heat pump does not run for free, my guess is your propane did not cost you much more if any more than the electricity would have to run the heat pump.