Ryan Thompson

I am still working on preparing my car for the 2,000 mile round trip to Sharktoberfest.

I would like my cruise control to work and have been testing. I searched the forum and google and all I see is HVAC related. I removed my AC pump as it didn't work and deleted the belt and pull on the motor.

I went through the WSM and the vacuum actuator fails. I even used my power probe direct on the leads of the actuator and it does not move the throttle at all.

How do you fix/repair these? or replace? where to buy?

All other checks were good with connector for cruise control.

Also, does this mean I have a vacuum leak, or does the check valve by the brake booster take care of this? I put a mighty vac on the test port, by the brake booster, and wouldn't hold at all when pumping.

joejoe

You need to remove front driver wheel, abd fender skirt. There is the vacuum canister and cc unit. You may find something there. Usual suspect is the 'brain' itself. Do all your vents work correctly? If no then vacumm leak very possible (usually diaphrams) Hope this helps some.

Ryan Thompson

Vacuum Canister "actuator" VDO Tempostat FAILS. I removed the drivers side wheel and liner to access. I put vacuum on the actuator itself where hose #4 would go and 12v to the electrical connector. I hear something trying to work, but no throttle movement at all.

Ryan Thompson

I also tested the Vacuum Servo "actuator canister" and jumpered between 3 and 5 on the CC connector. Then turned on ignition and connected 7 and 12 momentarily, with no throttle movement. This is the same as applying 12v to the Vacuum Servo "actuator canister"

Ryan Thompson

Anyone ever dismantled one of these?

Mrmerlin

chances are you not getting enough vacuum to your servo unit due to a leaking HVAC system.
SO to test this theory plug in the myty vac to the CC servo and see what the vacuum is,
it should be around 19 at idle.

Then unplug the black vacuum line from the 4 way connector at the booster (this goes to the HVAC system) and plug the 4 way then retest the CC unit.

Usually when a CC unit fails to operate it is due to the CC brain thats under the right side console.
That guy Kristopher Rose rebuilds the Porsche CC brains,
look for a Mercedes Benz HVAC unit repairs.