The unit turns on when thermostat temperature is set higher than room temp. It blows cool air for several minutes and then the emergency heat kicks on and warmer air comes from vent. This lasts for several minutes then shuts off, air continues to blow but is now cool again. At this point room temperature never reaches the set point the unit continues to run continually until it is shut off at the thermostat.

  • What is the outdoor temperature? What is the set point on the thermostat?
    – Tester101
    Commented Feb 21, 2015 at 18:14
  • it seems to do it now at any temperature outside that we need the heat although it was first noticed when we were getting temp's in the 30's but is now doing it constantly. We normally have the thermostat set at 75 when the temp is Florida cold.
    – susan
    Commented Feb 23, 2015 at 19:16
  • I found out that the above problem was due to a couple of leaks in the outdoor unit that caused the Freon to be lost. Had the leaks welded and replaced the Freon. Cost $250.00.
    – susan
    Commented Mar 23, 2015 at 10:19

1 Answer 1


In the heat mode the larger copper pipe going to the AC unit outdoors should get very hot, if not then the refrigerant might be low or the reversing valve which switches modes from Cool to Heat may be bypassing. the fact it shuts down tells me its getting overheated likely due to low refrigerant level.

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