Testing AC/heater Vac System


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Well-known member
Aug 5, 2019
Reaction score
QLD Australia
My Car
1973 Mach 1 Sports Roof.
Q code. 351-4V
C6 Auto, 3.25 Rear Axle, AC, Power steering.
My build project included a complete overhaul of the AC/heating system. I needed a method to initially test the vac motors and then the system once installed without the motor running.
I had an old 12V Jumper Pack that had a tyre inflator. Battery died so pulled it apart and kept a few bits. The small compressor had a hole in the head for the air inlet,
so I fitted and epoxied a piece of brake line into the intake hole and converted it into a vacuum pump. Mounted it upside down to allow for the occassional oiling.


The pump vacs higher than normal car vac, so after experimenting with different small holes in the intake line I was able to maintain normal manifold vacuum. Probably a small trickle irrigaton tap, tee'd into the line would give better control. It can be connected anywhere in the system and to the vac tree line going to the vac canister.
I have used this many times, getting the vac motors adjusted, checking for leaks, the vac canister, etc, without having to start the engine.

Also useful for fluid extraction, brake bleeding, etc.

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