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Issue with Carrier infinity heat pump

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zepfan
zepfan Member Posts: 470
in A-C, Heat Pumps & Refrigeration

we are having an issue with a carrier infinity heat pump model# 38ydb060320.
installed in 2006. The issue the system runs fine for a few days, then locks out on Code 6 “thermal cut out in high stage. The unit is reset, and the unit restarts. I was out last week and the compressor was not hot at all. The system was running a 125-325 (410 a) with a 90 degree outside ambient. 10 degrees of subcooling, and 12 degree super heat. Everything seemed normal. According to the manual for the unit this could either be the overload in the compressor tripping prematurely, or the start relay not opening. I had a meter across the start capacitor and the relay seemed to open every time I cycled the unit. The unit ran fine for three days and then tripped out again today.
I guess the board could be bad, but was wondering if anyone else has had this issue? And is it possible to run the unit on just low stage? It never displays a cutout in low stage, and the home has several other systems, and this one appears to be oversized. This would just be a temporary fix as the homeowner knows based on the age of the heat pump, it will need to be replaced eventually.

The system has a communicating air handler attached to it (FE4A) and the first generation infinity user interface. Any suggestions would be much appreciated

Thanks to all

Comments

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 20,545
    edited June 13

    Is the thermal cutout wired to the board? How does the control know it is the thermal cut out?

    What I am getting at is you could wire a "tattle tale" or a low amp fuse across the thermal cutout to prove it is tripping.

    You just have to make sure the amp draw on the overload circuit is more than the fuse or tattle tale is rated for.

    Don't see any reason you could not run on low stage, it should have a two stage stat.

    I found the manual it talks about the VC/VH trip but doesn't describe what makes it trip. Looks like two wires from the control board to two legs of the 240 volt they must be monitoring the compressor amp draw somehow through the board.

    zepfan
  • pecmsg
    pecmsg Member Posts: 7,311
    https://forum.heatinghelp.com/discussion/comment/1898455#Comment_1898455

    with computers it doesn’t work like that!

  • 109A_5
    109A_5 Member Posts: 4,223

    How did you determine it is just high stage fault, I'm not getting that from the description (different manual maybe ?). A Y2 lockout locks out both Y1 and Y2.

    Seems that code is for low voltage. I trust you inspected the L1, L2 wiring all the way back to and in the circuit breaker panel. Was the voltage measured at the compressor during a Y2 call ?

    image.png

    https://siglernorcal.com/docs/service/VC-VH.pdf

    VC=Voltage common; VH= voltage hermetic.

    image.png image.png

    https://www.shareddocs.com/hvac/docs/1009/Public/0D/38YDB-5SI.pdf

    https://siglernorcal.com/docs/service/VC-VH.pdf

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • 109A_5
    109A_5 Member Posts: 4,223

    OK, I guess you are seeing this.

    image.png

    Seems like you have eliminated some of the expected causes.

    image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • 109A_5
    109A_5 Member Posts: 4,223
    https://forum.heatinghelp.com/discussion/comment/1898455#Comment_1898455

    "Is the thermal cutout wired to the board? How does the control know it is the thermal cut out?"

    I suspect no phase shift voltage differential VC to VH (Voltage across the Compressor Capacitor) due to no compressor load since the thermal cut out is open (when and if that scenario is happening).

    image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • zepfan
    zepfan Member Posts: 470

    thanks to all that responded. The thermal cut out is the actual internal overload in the compressor. I suspect that it is either prematurely tripping, the board is bad, or the ODF is locking up. If that were the case I would think there would be a hp cutout error.
    I think the board senses thermal cutout by seeing that the compressor contactor is energized, and there is no amp draw on the start winding.


    Strange thing is since I posted this the unit has been online and cooling with no alarms

  • mattmia2
    mattmia2 Member Posts: 17,562

    did you check the caps by measuring the voltage across and current through and calculating the capacitance and comparing it to the rating? i'd check the fan cap too while i was there. it is confusing tht they use the nonpolarized capacitor symbol for relay contacts…

  • 109A_5
    109A_5 Member Posts: 4,223
    https://forum.heatinghelp.com/discussion/comment/1898500#Comment_1898500

    "I think the board senses thermal cutout by seeing that the compressor
    contactor is energized, and there is no amp draw on the start winding."

    So how does it measure the "amp draw on the start winding" ???

    I'm sticking with;

    The no phase shift voltage differential VC to VH (Voltage across
    the Compressor Capacitor) due to no compressor load since the thermal
    cut out is open (when and if that scenario is happening).

    Especially since either the S or the R compressor winding can be the start winding.

    image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • pecmsg
    pecmsg Member Posts: 7,311

    it meat thermistors resistance.
    find the cause!

  • pedmec
    pedmec Member Posts: 1,469

    I believe that you might have a bad compressor. The carrier infinity 2 stage units used to use the Bristol compressors. They didn't unload a cylinder or have the DC voltage solenoid built into the dome of the compressor for staging. They were built to reverse direction for high or low function. I would check to see if this is a Bristol compressor first and if it is reach out to Carrier for tech support

  • Upnorth45TC
    Upnorth45TC Member Posts: 3

    I believe every time I have encountered this specific error code it required a replacement of the compressor. If I remember correctly the error code generated references the condition (damaged in this case) of the internal windings of the compressor. I hope I am wrong for the sake of the homeowner.

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