I have a Coleman gas furnace in a wall space in my house which somehow shares the blower on my a/c unit on the roof because it turns on when furnace is called to start, though it does bump up after a few minutes when the furnace ignites (which tells me it has its own blower motor) and both are controlled by a single thermostat and shuts off when satisfied.

My problem, only 1/3 of my house is getting warm air blowing through the registers other 2/3 is mild to cold air. All registers have adequate air flow. It causes our room to get very warm while others are cold. In the summer I had a Freon leak and they took the a/c unit somewhat apart to find it. Not sure if somehow they put it back together incorrectly and there lies my problem. I have yet to go in the attic or on the roof. Any suggestions or leads would be helpful.

  • Is the air conditioning running while the system is calling for heat?
    – wallyk
    Jan 2, 2015 at 23:07
  • Are you sure it is not a heat pump on the roof with a gas furnace for back up heat?
    – wallyk
    Jan 2, 2015 at 23:09
  • A picture or model number of the two units might be helpful. What you are describing seems highly unusual, and possibly suspect.
    – mfarver
    Jun 1, 2016 at 0:14

1 Answer 1


Your A/C unit on the roof should only start running if it's heat pump, and it definitely shouldn't be running at the same time as the gas furnace.

I'll take a guess that your thermostat is wired incorrectly, and it's running the air conditioner and furnace at the same time.

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