I have a 1999 Olds Aurora and when I turn the front defrost the Air Conditioner turns on and I can't turn it off. Is that what I want to happen? It doesn't do that on my other 2 cars. How can I fix that?

  • Welcome to Motor Vehicle Maintenance & Repair! Dec 29, 2018 at 17:30

1 Answer 1


This is actually typical in many different vehicles. The idea is, when the defroster is on, the A/C kicks on to take the humidity out of the air, which then gets blown onto the windscreen, which dries it out allowing it to defog quicker. Some cars are setup like this while others aren't.

This really isn't a bad thing, for two reasons:

  1. It keeps the A/C parts moving and lubed during times when you wouldn't normally be using them.
  2. As stated, it clears the inside of the windscreen faster.

Bottom line is: It's this way by design.

  • Yep.. this is extremely common and by design. My current and previous two daily drivers both did this. Jan 2, 2019 at 11:44

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