When I turn off the AC it continues to blow cold air for several minutes. I realize this may be an energy savings feature, but I'd like to know if it is possible to disable it. In other words, what I'd like is for "Off" to be immediate off. I realize this is not something I may be able to do on my own, not really expecting to. I want to know if an HVAC technician would be able to modify this setting.

I apologize in advance, I have very little HVAC knowledge, but I am able to list the following installed components:

  • Carrier Split-System Condensing Unit - 38HDR
  • Carrier Gas Furnace - 58MCB
  • Nest Thermostat (Airwave is disabled)

Btw - I have the same problem with heating, not just cooling.

  • 1
    Looks like your furnace has an adjustable blower off delay from 90 - 180 seconds, so you'll be limited to that. While some units don't use the delay when in cooling mode, it sounds like yours does
    – Tester101
    Jun 20 '15 at 12:36

This is basically a safety feature. In the case of heating, if the fan turned off immediately after turning off the thermostat, the heat buildup in the heat exchanger could cause it to eventually crack and leak carbon monoxide into your house, so the fan continues to blow until the heat exchanger sufficiently cools. In the case of the A/C, there's no danger of carbon monoxide. But if the various coils in the A/C were allowed to heat too rapidly, that could also cause their premature failure, so the fan continues to blow air across them until they're within a few degrees of ambient. If this were able to be disabled and you could find an HVAC tech to do so, I wouldn't hire him or her, nor the company for which they worked.

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