Heater and A/C not working

Discussion in 'HVAC Heating & Cooling' started by tjk34, Oct 29, 2013.

  1. tjk34

    tjk34 New Member

    Messages:
    7
    Location:
    CA
    Hello, I have a Payne Heater and cannot remember the A/C brand. We last used the A/C in August, all month. We went to fire up the heater and it does not work. The thermostat clicks on and flashes "heat" (normal) but the blower never comes on. We then tested the A/C and same thing. Does this mean we have a bad blower? No breakers are flipped
  2. Dana

    Dana In the trades

    Messages:
    2,790
    Location:
    01609
    There could be many things in the control link chain that would inhibit the blower from turning on. A model number might yield a web-available schematic to work from.

    Do the gas burners light off when you turn the thermostat on?
  3. DonL

    DonL Jack of all trades

    Messages:
    3,820
    Location:
    Houston, TX

    Is your thermostat battery operated ?

    Does it have a Fan Mode ?
  4. tjk34

    tjk34 New Member

    Messages:
    7
    Location:
    CA
    Model # PG8JAA048090 where do I check the gas burners?
  5. tjk34

    tjk34 New Member

    Messages:
    7
    Location:
    CA
    Yes, battery operated. Yes, fan mode present but no fan is kicking on either
  6. dj2

    dj2 Member

    Messages:
    399
    Location:
    California
    You need a precise diagnosis, maybe from a tech, but if you want to try it yourself, download a manual online and follow the troubleshooting guidelines. I have a feeling that it will be too hard for you.
  7. tjk34

    tjk34 New Member

    Messages:
    7
    Location:
    CA
    Well, between myself, my husband, and our voltmeter, I was hoping to narrow it down to a specific part. We have repaired electrical before; however, we have not worked on HVAC
  8. dj2

    dj2 Member

    Messages:
    399
    Location:
    California
    Listen, I always encourage people to fix things themselves, why not?, but there is a point of diminishing returns, where DIY becomes more expensive (and more frustrating) than hiring a pro.

    Call a tech, now is not the time to learn HVAC in 3 hours.
  9. DonL

    DonL Jack of all trades

    Messages:
    3,820
    Location:
    Houston, TX

    Getting it to work in fan mode would be a good place to start.

    No need to mess with the burner.

    If your batteries are good and the unit is getting power, the fan should work.

    You should check to see if someone turned off the power at the Service Disconnect switch near the unit.

    You may want to cycle the Breaker for both the indoor and outdoor unit.


    Then call Sears if needed.


    Good Luck.
  10. tjk34

    tjk34 New Member

    Messages:
    7
    Location:
    CA
    Thank you DonL :) The Service Disconnect switch is in the ON position and thermostat is operable. We will switch out batteries in thermostat just to rule out the possibility that the batteries may be weak. Hubby is ready to change out the blower but I wanted to rule out minor things first. Thank you for your advice
  11. DonL

    DonL Jack of all trades

    Messages:
    3,820
    Location:
    Houston, TX

    If you put it in A/C mode, then the outside fan and compressor should run if the controller is working, even if the indoor blower does not work. But it will Ice up quick and you do not want to operate long like that, just for short test is OK.

    Blowers normally make strange noises before they smoke. If the T-stat is working and the outside unit runs in AC mode, then it could be a bad connection to the indoor blower motor.


    Good Luck.
    Last edited: Oct 29, 2013
  12. tjk34

    tjk34 New Member

    Messages:
    7
    Location:
    CA
    When I put on A/C mode, nothing turns on at all. My hubby got a voltmeter to test L1 and L2 wires in heater and also wires in thermostat and he is getting a zero reading. I am thinking he does not have a proper ground? Can a screw be a solid ground? Basically, nothing is coming on at all - just the thermostat is flashing the words "heat" or "cool" depending on which unit we are testing. Also cycled breaker but did not help
  13. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,830
    Location:
    New England
    Did you change the batteries in the thermostat?

    Control voltage to/from (most) thermostats is 24vac. If you happen to check it on dc, you will get zero volts. And, you will often get ambiguous results trying to measure that 24vac to ground...the return often is not connected to ground (directly anyways). Many thermostats do not end up with the 'other' side of the 24vac transformer, so there is no reference there at all.

    While there are conventions on how the leads are labeled, it's safest to review the system's schematics. The 24vac transformer must be outputting 24vac (often, it's a bit higher than that) for anything to work.

    In a typical thermostat, one side of the 24vac transformer comes in, and when say you turn it to fan, it connects that voltage to the fan circuit, it goes through a relay in the furnace, energizes it with the circuit being completed because the other side of the relay's coil is connected to the other side of the 24vac transformer.

    Same idea with the heat, connect that 24vac back to the furnace, goes through (usually) a relay, turns the things on.

    Again, same with the a/c.
  14. tjk34

    tjk34 New Member

    Messages:
    7
    Location:
    CA
    Yes, we changed the batteries in the thermostat and we had the voltmeter on AC reading. What setting should it be on please?
  15. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,830
    Location:
    New England
    This is a basic diagram that shows how a typical unit works. As you can see, to measure the 24vac control circuit, many thermostats have no reason to have both sides of the transformer there. If it is there, it would often be a black wire, but be careful...what the label says and the actual color of the wire that's there may not be the same! It certainly makes life easier, but people don't always buy a cable with the common colored wires in them, and as long as they're careful, it really doesn't matter.

    Attached Files:

  16. DonL

    DonL Jack of all trades

    Messages:
    3,820
    Location:
    Houston, TX

    You should check your 24V transformer for power, Using the AC Range on your meter.

    Sounds like the transformer is not getting power or is bad, or you have a broken low voltage wire conductor.


    Do you understand Jim's wiring diagram ?


    P.S. Ground has nothing to do with it, It is AC not DC like you may be thinking.
    Last edited: Oct 30, 2013
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