yellowone

On my 72 Cutlass Supreme I think my temperature lever valve is bad. At the water valve I have 15 inches of vacuum at idle when the lever is in the cool position. It goes to 0 inches of vacuum in the warm position. Which is corrct to operate the water valve. However when I move the lever just to the left of warm it goes back to 15 inches of vacuum. Does that mean the temperature lever valve is bad? Shouldn't it have varying vacuum depending on where the cool/warm lever is positioned? Thus varying the degree of heat that comes into the cabin of the car? Help anyone?

Fun71

The water valve on the intake manifold is either fully open or fully closed; there is no partial vacuum operation.

Is this an AC or a non-AC vehicle?
The vacuum should change when the upper lever is moved from the OFF position to the HEAT or AC positions. The lower lever operates a cable that moves the air blend door to allow either warm air from the heater core or cool air from the vent/AC ,or a combination of both, to enter the vehicle.

Koda

That lever has a heater core lockout that is on or off and it is at full cold vs just to the right of that. You can feel it click it. The other thing it does is control the blend door over the whole lever. Temp is controlled by the blend door routing some percentage of air over the hot heater core. Max cold ALSO shuts down the heater core with that lockout. In other words, it's working right.

oddball

As said, the correct function of the vacuum switch in the heater control panel is far left (COLD) applies vacuum to the hot water valve. Moving slightly off of far left removes vacuum and remains vented for the rest of the lever sweep. The lever also moves the blend door which is what you actually feel through the lever, and the blend door actually controls the final air temp.

The heater panels are pretty simple units, so you can see if it's something obvious. It's very difficult to repair one of those vacuum switches (I've tried!) and you can't use a hand pump to test them. Almost all of them leak these days, so you need a constant vacuum source. Note that the heater control is removed from the back side of the dash with 3 screws, usually hex heads, so it's super easy to remove. Once the dash is removed from the car.

Folks on here have good units they sell (post a parts wanted ad). I did find one company that reconditioned the vacuum switches and had an assortment of old stock on hand. Been too long since I last looked them up though..... Might have been Old Air Products or one of their competitors, I think they had a bunch of ebay ads with various vacuum switches.

yellowone

So mine is defective as it only releases the vacuum when it is fully on warm. and applies vacuum everywhere else. Guess I will try to find one. Hopefully NOS. Thanks for the help all.