Announcement Announcement Module
Collapse
No announcement yet.
Ok Bill your turn Page Title Module
Move Remove Collapse
X
Conversation Detail Module
Collapse
  • Filter
  • Time
  • Show
Clear All
new posts

  • Ok Bill your turn

    Carrier 38TDB036. Looked at it for my buddy earlier. I have a call for first and second stage cooling from the IFC to the control board on the condensing unit but only second stage is running. This unit has 1 contactor for each stage. Second stage contactor has a 24 volt signal but the first stage contactor does not. Pressures were really low when unit was running on only second stage.

    Im losing my call for first stage cooling in the condensing unit control board. I robbed the second stage signal wire and hooked it to the first stage contactor. The pressures were alot better. Figuring this unit was going to be running for a few days like this i went ahead and charged the unit accordingly. Started out with 30 degrees of superheat and ended up with 12.

    Any idea how carrier is staging this stinking thing?

    Andy

  • #2
    Re: Ok Bill your turn

    Staging is normally done through Temperature Deltas (Indoor and outdoor)

    Here is a link to the docs for this condenser

    http://www.commercial.carrier.com/co...PRD664,00.html


    This condenser should have on board diagnostics. I think there has to be at least 3 wires to the condenser to make onboard diag not reset at control power shut off (24 V supply to condenser all the time)

    Is this condenser paired with a variable or 2 speed evap blower? (If you robbed the second stage signal wire does the evap blower know that?)

    What type of control system is this system using? (standard 4 or 5 wire, solid state or electronic)

    How old is this system ( 5 year parts, 10 year compressor)

    Is this system using a standard TXV or an electronic metering device?

    Bill

    Comment


    • #3
      Re: Ok Bill your turn

      Originally posted by OkieBill View Post
      This condenser should have on board diagnostics. I think there has to be at least 3 wires to the condenser to make onboard diag not reset at control power shut off (24 V supply to condenser all the time)
      It does have onboard diagnostics but it never flashed any faults. Other than a VC/VH trip from me messing around.

      Originally posted by OkieBill View Post
      Is this condenser paired with a variable or 2 speed evap blower? (If you robbed the second stage signal wire does the evap blower know that?)
      Variable drive. I just assumed since I had a Y1 and Y2 signal from the IFC, the blower would know where it needed to be. Unless you are implying the condensor is going to report back to the IFC and confirm what stage is firing, but I dont think that is the case.

      Originally posted by OkieBill View Post
      What type of control system is this system using? (standard 4 or 5 wire, solid state or electronic)
      I never even went to the stat. I did forget to mention the outdoor unit was wired to the R,C,Y1,Y2 terminals and not the ABCD.

      Thanks for the link. I read through some of the docs but I still dont know how this thing is staged. Does a call for second stage close both contactors? Or does it drop out first stage then fire the second stage which is 100%? I tried manually closing the second stage contactor while the first stage was running. It didnt like that at all. Another thing that confuses me is why my pressures were so low when the second stage contactor was the only one closed. And when I did get first stage to fire (by robbing the second stage signal) why the first stage only pressures were within reason.

      Now I remember why im not a Carrier dealer! Thanks for the help so far!

      Comment


      • #4
        Re: Ok Bill your turn

        Originally posted by Ruudacguy View Post
        It does have onboard diagnostics but it never flashed any faults. Other than a VC/VH trip from me messing around.



        Variable drive. I just assumed since I had a Y1 and Y2 signal from the IFC, the blower would know where it needed to be. Unless you are implying the condensor is going to report back to the IFC and confirm what stage is firing, but I dont think that is the case.


        I never even went to the stat. I did forget to mention the outdoor unit was wired to the R,C,Y1,Y2 terminals and not the ABCD. ABCD is for the electronic control system "Infinity", Staging is controlled by the brains on the furnaces control board along with the stat.

        Thanks for the link. I read through some of the docs but I still dont know how this thing is staged. Does a call for second stage close both contactors? I have always thought the speeds were seperate windings so seperate contacts for each speed.

        Or does it drop out first stage then fire the second stage which is 100%? I tried manually closing the second stage contactor while the first stage was running. It didnt like that at all. Another thing that confuses me is why my pressures were so low when the second stage contactor was the only one closed. And when I did get first stage to fire (by robbing the second stage signal) why the first stage only pressures were within reason. (When you are changing speeds at the condenser is the IBM changing as well?) If you are faking out the condenser how does the Evap blower motor know what you are doing? This may be a cause for your pressure problems at one speed but not the other....

        Now I remember why im not a Carrier dealer! Thanks for the help so far!
        bill

        Comment

        Working...
        X