Heater not turning off

Discussion in 'HVAC Heating & Cooling' started by Kajun, Feb 9, 2010.

  1. Kajun

    Kajun DIY Junior Member

    Nov 5, 2009
    I have a mobile home that has a central a/c and heating unit....the last few months my electric bill is sky high....almost $300 each month....i suspect the problem being the central unit.....when it reaches temperature on the thermostat it will quit heating but the fan stays on until i have to manually turn it off...to do this i usually have to turn it off a few times before it actually works...

    any ideas to what is causing this?..thermostat bad? fan switch bad?

    my other problem is ..my house gets heated or cooled unevenly....the back portion of the home gets hot/cold quick.....while the other end of the house doesnt cool/heat properly......the air flow coming through the floor vents is much better at the back end which is where the unit is located.......any ideas on this...how to fix it?

    any help would be appreciated.. thanks!
  2. Cass

    Cass Plumber

    Nov 12, 2005
    You realy need some one who works on trailers to look at it and see if all the vents are hooked up right and check the system over...have you changed the filter....
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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    It sounds like the ducts are leaking or disconnected so the air is not being distributed properly. Often, a furnace's fan has two modes: automatic and manual. On automatic, many sense the heat exchanger's temperature and run the fan whenever it excedes a pre-set temperature, so it is normal for the fan to run for at least a little bit after the furnace stops heating. This allows it to extract the heat you paid for. The suggestion to check the filter is very good in that if it is plugged up, the fan won't be able to move much air across the heat exchanger, and that could be part of the reason why you don't have the airflow you need. It would also allow the heat exchanger to get hotter than it should.

    The sensor that turns on the fan could be dirty or bad, but the first thing to check would be the filter and ducts. I suppose the thermostat could be bad (assuming it has a fan selector switch - not all do and even if it does, it may not be hooked up), but they are usually pretty reliable. At the thermostat's location, does it turn the furnace on and off properly? If it has a fan switch, does that work? Or, does the temperature overshoot, or what?
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