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Thread: how to make the heat pump run?

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  1. #1
    DIY Junior Member Henry Lee's Avatar
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    Unhappy how to make the heat pump run?

    I live in Virginia. The temp is around 45F. I have Ducane heat pump outside. it is not running at all but the inside furnace fan is working well. I just changed the defrost circuit board since the HVAC service guy said the old one needed to be replaced. The thermostat seems in good condition because i just got a new Honeywell 5-1-1 programming one and works well. So far, the defrost circuit board and thermostat are all brand new. What is the problem to cause the heat pump not running? I pressed the valve button on the heat pump which can make it run. But it stops if i release the press. Is there possible to be the circuit board wiring problem?

    Any advice is appreciated. it is so cold here.

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
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    Sounds sort of like you had a refrigerant leak, and the system is low, causing a lockout. This is likely something a service tech might need to look at. If the reverse switch valve is not working, it can't make heat. Don't know enough about a heat pump to help more. Does the thermostat have a setup so it can control a heat pump? Is it hooked up properly? There may be a dip switch or jumper that needs to be moved. Carefully read the installation instructions again and make sure you use the section on a heat pump to verify it is wired properly.
    Jim DeBruycker
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    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    Moderator & Master Plumber hj's Avatar
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    Not all thermostats are compatible with heat pumps, so that MIGHT be a factor. I am not sure what that button does, so cannot comment on whether it is bypassing some safety circuit, or not being energized by the air handler or thermostat.

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    DIY Junior Member Henry Lee's Avatar
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    I bought the brand new Honeywell TH6320U1000 5-1-1 Programmable Thermostat. It works for heat pump. The HVAC service guy came and set the thermostat and air handler wiring. He said if i got the new circuit board and get it replaced. It should
    work. But it didn't work as the guy told me.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    Recheck the wiring...http://customer.honeywell.com/techli...69-1920EFS.pdf There are lots of ways to mess up the programming. If the thermostat is not setup for exactly your type of system, it won't work; it's not just geting the wires to the right place, you have to program the computer for exactly the type of system you have.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    DIY Junior Member Henry Lee's Avatar
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    thanks for your reply.

    Thanks for the reply from jadashua.

    The heat pump is not running at all but the inside furnace fan works and gets some heat. I just changed the defrost circuit board since the HVAC service guy said the old one needed to be replaced. Freon level is ok. I pressed the button (contactor) on the heat pump and it ran. But it stops running if i stop pressing the contactor. So you think i need go back to recheck the thermostat wiring?

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    Plumber jimbo's Avatar
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    On as thermostat like your new one, you have to go through the set-up program and set up the O/B function. That is, there is a terminal which will signal the outside reversing valve. That terminal may be set to send 24 volts on a call for HEAT, or a call for COOL. It probably defaults to call for cool. You need to find out on -your heat pump which way the reversing valve works, and then program the T-stat accordingly.


    But....if the outdoor unit does not turn on at all ( fan running? compressor running?) then it is a problem besides the reversing valve.
    Last edited by jimbo; 12-04-2010 at 07:18 PM.

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    General Engineering Contractor ballvalve's Avatar
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    Love those guys that change parts as a method of troubleshooting.

    If its too cold, seems the pump would shut down and call for the heat strips to cut in. Maybe the strips do not work?

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    DIY Junior Member jseger's Avatar
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    Henry,

    Did you ever figure out what the problem was with your heat pump? I live in VA as well and have the exact same issue. HVAC technician came in and said the wall thermostat was bad. He installed a new Honeywell thermostat but the heat pump still would not work. Then the technician said the Defrost Control board on the heat pump was bad. That was replaced with a new one and the heat pump still does not work.

    If I manually press the contactor on the heat pump, it comes on. So it does not seem to be the contactor or compressor. I double checked the thermostat connections and settings and they are exactly as prescribed in the instructions. Next step might be to put the old thermostat back and see if that works.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    Sometimes, the installer may not follow the recommended color code on the wiring, and if you blindly install a new thermostat without carefully marking the old one's wire positions, it will never work. So, check out the air handler side to ensure that the wires are on the 'proper' places, then check the thermostat again. Ideally, it should be just a straight-through red-red, yellow-yellow, etc...but if someone was sloppy???
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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