Results 1 to 11 of 11
  1. #1
    Join Date
    Feb 2010
    Location
    Milwaukee, WI
    Posts
    62

    OAT failure effecting the heating cycle?

    Working on a Carrier M# 48HJ3006. The unit is on CCN. It is telling me there is a OAT sensor failure (reading -40). Is it effecting the heating cycle? I have to reset the unit to start up the heating cycle but it will eventually lock out again.

  2. #2
    Check unit manual if available, if not talk to carrier. I believe those sensors have a variable resistance depending on temperature. OHM out the sensor and compare to charts in manual (or what carrier tells you) if the sensor seems accurate then the board has failed. If the sensor reading is way off then you need to replace the sensor.

  3. #3
    Join Date
    May 2004
    Location
    SE Pennsylvania
    Posts
    927
    Unit manual http://www.docs.hvacpartners.com/idc...8-50h-t-2t.pdf

    The OAT sensor will only effect the economizer and low ambient cooling lock out. Is there a code for the heating module?

  4. #4
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
    Posts
    3,718
    It there a premierelink controller in the unit?

  5. #5
    Join Date
    Jul 2009
    Location
    Columbia, MD
    Posts
    3,973
    i don't know much about this unit but, most units are rated to work down to -40*f ambient. if your sensor is reading -40* it might lock out the unit because its too cold.

  6. #6
    A -40 reading on the ccn is either an open sensor, a disconnected sensor or possibly a bad input. This will not effect your heat stage at all. Is it a VVT system or conventional? If its VVT, heat will be based on your supply air. If conventional, it will be off your space temp sensor. Have a look at your occupied/unoccupied settings also.

  7. #7
    Join Date
    Feb 2010
    Location
    Milwaukee, WI
    Posts
    62
    yes, the preimer link is mounted on the duct below the unit.

    That's what I thought too that the OAT is only for the Econmizer but it seem to be locking out the unit. And there is no code for heating module.

    I just want to make sure that it is the OAT that is causing the problem and not the board too.

  8. #8
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
    Posts
    3,718
    Quote Originally Posted by xxcels View Post
    yes, the preimer link is mounted on the duct below the unit.

    That's what I thought too that the OAT is only for the Econmizer but it seem to be locking out the unit. And there is no code for heating module.

    I just want to make sure that it is the OAT that is causing the problem and not the board too.
    When you say it locks the heat out is the plink in heat mode? Is there a fault code on the igc?

  9. #9
    Join Date
    Feb 2010
    Location
    Milwaukee, WI
    Posts
    62
    After some troublingshooting today I notice on the ccn that the SFS (supply fan status) is off. But the blower fan is running. I reset the unit. It goes through its normal heating operation but the cnn never detected that the fan kick in. How do I check my fan status? Before ruling that it is a bad board.

  10. #10
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
    Posts
    3,718
    Is the fan status input even being used?

  11. #11
    Join Date
    Feb 2010
    Location
    Milwaukee, WI
    Posts
    62
    I got 24v at the board. I traced it to the unit. The wires go into this little gray box (not sure what it is call) that clamp around a blue wire going into the fan relay. I am pretty sure that is where my problem is. But then I moved it around and BAMN! the heatin kicked in and the cnn detect the SFS.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event