I have an 86 740 turbo diesel. The heat is always on! Slightly if I slide the slider to the coolest and hot if I go to the hottest. My heat also blows out of all of the vents and does not change as I select the different vent regions. I believe this to be a vacuum problem and actually may have the culprit!
I get no vacuum at the heat control panel and I do have a disconnected vacuum line running through the firewall. I think it is a large gray one. It is not the one going to the heater control valve, that one is good!

Any ideas?
Can anyone tell me where this vacuum hose should go?
thanks

Does it have a vacuum pump ? I think it does because its diesel where does your brake vacuum booster hose go to ?

yes it does have a vacuum pump. The pump goes to the brake booster by way of a thick rubber hose. There is a "T" there and one end goes to the booster, the other to a white plastic valve that has a short chunk of hose on it with a bolt in the hose.
I thought this was weird.
It is in the pic behind the 2 red wires and the 2 copper lines. You can barely see the white plastice covered by hose on both ends, the one to right has the bolt in it.

If this is my problem, how do I connect the vacuum hose to this larger plastic valve???

I pulled the bolt side hose off and oil started to drip out. Is this ok? I fell as though it is not. What does it mean?



Thanks
Steve

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The heater control vacuum hose should connect to where the bolt is when you removed the hose with the bolt in it and oil came out are you sure its oil ? do your brakes work good ? are you sure its not brake fluid ? you can still try connecting the hose for the heater controls and see if it works If the hose size is different you can use a hose nipple from one size to the smaller size so it fits.

got it thanks!
Heat and controls work, brakes work!
I think that it is oil, must be my vacuum pump is starting to leak.

thanks
Steve