A friend of mine has the vac box by the windsheild wiper motor and has the line which goes to the controls but the other one is missing... He believes this is the reason why his defrost is the only control which works besides off.

What sounds the problem here?

Thanks

 

The other line os supposed to be hooked to engine vacuum. The tank you're referring to is just a storage tank to make sure the environmental system always has vacuum. And yep, that's why he only gets defrost air blowing. That's the "all vacuum controls off" default configuration.

Usually the missing vacuum line gioes thru a check valve and then hooks to a T in either the distributor vacuum advance on the pre-TPI models or a T in the EGR vacuum line.

Good Luck!


- Vern

 

Thanks Vernw, that was very helpful.