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Heater not working

We have a brand new home with brand new hvac unit. The heater will not blow hot air. Have no issues with the ac. We've done the following trouble shooting:
- unit has a brand new filter
- Pilot-less unit and it is running. Not pilot issue or breaker issue
- Gas to unit is on position
- Thermostat is set to heat and fan auto
- When fan set to on, it does blow cold air. Not duct blockage

Not sure what else we can try. The home has two units and the other one is working just fine in heat mode.


  • BobCBobC Member Posts: 5,170
    Might be a safety has tripped, what make and model is it? Pictures might help.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • AbracadabraAbracadabra Member Posts: 1,948
    Need model and flash code from the control. Open up the front cover, the control should be flashing a red LED. Count the number of flashes. They will repeat.
  • michelle_10michelle_10 Member Posts: 5
    Trane Xb Model 4txcb031bc3hcba
    3 red flashes
  • michelle_10michelle_10 Member Posts: 5
    As I was down here getting the info, the unit is running for about 2 minutes and then turning off for 30 seconds.
  • FredFred Member Posts: 8,500
    It sound like the flame sensor isn't working but someone will know for sure what the 3 flashes indicates.
  • FredFred Member Posts: 8,500
    edited November 2016
    3 Flashes — Draft pressure error – possible problems: a) venting problem, b) pressure switch problem, c) inducer problem.

    You need to call a service tech
  • michelle_10michelle_10 Member Posts: 5
    edited November 2016
    Sounds like it's an "above the homeowners head" problem? Hahahahaha Or does it just sound more technical than it is? Is this normal for a unit that's not even a year old?
  • FredFred Member Posts: 8,500
    michelle said:

    Sounds like above the homeowners head problem? Hahahahaha

    Yep, call a service tech
  • Congratulations on describing the problem, and symptoms so well for us, and answering the questions so accurately.
    I wish everyone who has had a question here could have been capable of such good communication!
    Good luck, and keep warm.--NBC
  • michelle_10michelle_10 Member Posts: 5
    Thanks everyone for all the quick advice. Thankfully it's an unusually warm November here in Kansas. We're calling a service tech tomorrow. Until then, it's fireplace and gloves for us!
  • AbracadabraAbracadabra Member Posts: 1,948
    1. Check the intake for blockage, the exhaust for blockage
    2. Check the inducer
    3. Pressure switch failure is at the bottom of the list.
  • Harvey RamerHarvey Ramer Member Posts: 2,215
    Also, check all the condensate lines for blockage. Particularly the line coming from the bottom, exit of the secondary heato exchanger. If it gets blocked, the level of condensate inside can rise to the point of blocking the pressure switch tube attachment point. That will cause this same error. Also check all the "pressure switch" tube attachment points. Over the years they can start leaking as the latex or rubber hardens and cracks. Sometimes you can cut them back an inch and reinstall them, wrapping the attachment point with a small zip tie.
    Ramer Mechanical
    To learn more about this professional, click here to visit their ad in Find A Contractor.

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