I just moved into a new place and I want to make sure if this issue can be normal before contacting my landlord because I am afraid I am making a mountain out of a molehill. Let me start out by saying my A/C and heat work fine. It heats and cools. When I have my thermostat set to “heat” it runs until it reaches the desired temperature and then shuts off. However when I have my thermostat set to “cool” it runs until the desired temperature and then stops blowing air but makes a constant noise. I can’t even describe it except that it sounds like it’s still running minus the blowing fan noise. The outside unit makes noise as well. The noise itself doesn’t sound unusual just the fact that it continues on. I know it’s normal for a unit to continue to make noise for 5-10 minutes after the fans shutting off but I have never had a unit continue to make a noise like this and it will continue to make noise until I turn my thermostat to “off” or “heat” and yes the fan is set to “auto” not “on”. My a/c unit is a Trane XL1200. I read the manual but found nothing about this. I am wondering if maybe this can be normal and I just never noticed in the previous places I have lived before?

  • 2
    it's not normal. My daughter had a unit that the compressor continued to run & it eventually froze up.
    – Tiger Guy
    Apr 14 at 23:55
  • Is the noise from the condensing unit (outside unit) louder when the ac is on and blowing inside than when the blower (air handler) has shut off from the thermostat? Apr 15 at 20:11

1 Answer 1


It is not normal for the compressor to run after the fan shuts off. (In heating mode, it is normal for the heater to start and warm up before the fan starts to avoid a cold air draft, and normal to run a few minutes after the heater shuts down to harvest residual heat.)
You will be doing the landlord a great favor to call this to their attention, as it will shorten the life of the compressor. It will also raise the utility bill considerably.

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