HVAC question.

[Clone TIE Pilot]

If you hook a Mityvac up to the HVAC system, should it hold vacuum?

 

[455'ed80Regal]

Not like you would want an a/c system to hold vacuum when pulling it down, but it should hold one for a while. If it won't or bleeds off real quick there is a leak somewhere. Usually if there is a real bad leak, like on my car when I bought it, you can hear a vacuum leak with the car running. Mine was on the back of the heater controls.