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Q: AC blows hot and cold air at the same time

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I live in a very warm area, so I notice right away whenever something is up with my AC. Half of the vents in my 2007 GMC Acadia were blowing warm air the other day. I find it pretty weird that only part of the AC broke. The truck has just under 70k miles on it and I haven’t really had major problems so far. What part should be inspected first?

If you are getting normal cold air out of driver’s side and warm air out of center and passenger vents then you most likely have a bad temperature blend door actuator for the passenger side on the A/C evaporator case. Your system has two of these actuators, one for each side of your dash vents. This controls the temperature by getting feedback from the inside ambient temperature sensor. The sensor looks at the drivers and passenger seat temperatures and can alter the left and right side of your dash temperature output to compensate. You could have YourMechanic scan and test your A/C system for problems. Once a thorough diagnostic report is produced and indeed the actuator is deemed to be the culprit, YourMechanic can provide you with the best estimate for repairing the failed part.

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