Page 3 of 3 FirstFirst 123
Results 27 to 39 of 39
  1. #27
    Join Date
    Nov 2012
    Location
    Arlington, TX
    Posts
    11
    Thanks everyone for the suggestion. Ohmed out all the wires and couldn't find a short. Going to run new wire to the thermostat. Had tried a new thermostat, thought that may have been the problem, but it didn't solve it.

  2. #28
    Join Date
    Mar 2009
    Location
    Mid-Mo
    Posts
    3,595
    I like in situations like this to start wiggling wires while the power is off. Especially where it penetrates thru walls and the unit cabinet.

  3. #29
    Join Date
    Jun 2012
    Location
    Fayetteville, NC
    Posts
    289
    did you disconnect the t stat wires and check for shorts? I'd ohm out some the components you haven't changed i.e coils

  4. #30
    Join Date
    Nov 2012
    Location
    Arlington, TX
    Posts
    11
    Quote Originally Posted by SgtBone View Post
    did you disconnect the t stat wires and check for shorts? I'd ohm out some the components you haven't changed i.e coils
    Very last thing I checked was the t-wire. Isolated it from the system. Nothing. Replaced thermostat. changed the control box with one rebuilt with all new components (I work in a apartment community so I have the spares ready to swap-out). Got to be the wire. It's the only thing that hasn't been changed. I have another apartment's air handler doing the same thing. Fortunately, it's vacant and I suspect whatever is causing this issue is going to be the same problem.

  5. #31
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,069
    Hope your not using doorbell transformers.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  6. #32
    Join Date
    Oct 2002
    Posts
    1,309
    Think this out. Older systems do not usually have a "common" wire run to the stat. Short the wires, what do you have?

    CU wire short, blows only on cool call.

    Did poster say primary is blown, check 208/230 volt tap is correct. Is "common" conductor in stat cable run?

  7. #33
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,275
    Quote Originally Posted by jledford382 View Post
    Is it blowing on the primary or secondary side?
    Transformers ALWAYS blow the primary. The wires are fine and more turns. The secondary has fewer turns of thick wire and never blows.

  8. #34
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,275
    Had one where the tstat wire was ran across a roof w/o conduit. The sun dryrotted the insulation and it shorted when it rained.

  9. #35
    Join Date
    Oct 2002
    Posts
    1,309
    It is possible that "R" is grounding to a water pipe, but transformer winding has to be connected to ground on "C" side.

  10. #36
    Join Date
    Jun 2012
    Location
    Fayetteville, NC
    Posts
    289
    Ohm out all your coils inside and out, if one has low resistance that may be it. Low resistance through a coil is basically a short since there is little to no load

  11. #37
    Join Date
    Nov 2012
    Location
    Tahlequah OK
    Posts
    131
    Is this a heat pump? I have had contactor 24 v coils in the heat pump or condenser do this. They are just beginning to go to ground and are very erratic. Some of them would run for a while before blowing the fuse.

  12. #38
    Join Date
    Nov 2012
    Location
    Arlington, TX
    Posts
    11
    Quote Originally Posted by welling service View Post
    Is this a heat pump? I have had contactor 24 v coils in the heat pump or condenser do this. They are just beginning to go to ground and are very erratic. Some of them would run for a while before blowing the fuse.
    Turns out that this was the problem, along with a lot of other spaghetti wiring that the previous maintenance tech had done. Had the thermostat wired for a heat pump. Had to call out the original contractors to come out and look at it. Thanks every one for your help. I am new to the game and learning. BTW, it turns out the the blower motor was wired to run 240v for both cooling and heating, he fixed that as well. You guys rock. Have a blessed thanksgiving...

  13. #39
    Join Date
    Nov 2012
    Location
    Tahlequah OK
    Posts
    131
    miscand the blower uses 240VAC in both modes. The difference is motor speeds. It is lower in heating mode.

Page 3 of 3 FirstFirst 123

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