View Full Version : Isuzu NPR a/c air won't change from dash and floor vents

01-27-2010, 12:15 AM
Hey I have an 1998 Isuzu NPR 5.7l gas that has AC and Heater air only coming out of the dash and floor. The selector switch moves on the AC control unit but the air discharge is always on the dash and floor. What could be the problem? I have been told that the vacuum pump on the alternator could be bad. I looked at it but don't know how to check it. Is that even part of the AC system? Also, what all does the vacuum pump do on this truck?

Thanks For Looking

Drew Gemma
01-27-2010, 09:33 AM
I would start with the switch behind the dash first that is cheaper and mosre likly the problem.

01-27-2010, 09:27 PM
OK SOunds good to me. If I remove the AC control unit, where is the switch loacated or do you know the name of it?

Thanks for the advice