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What is this component -- the one with the red tab. This is the RH side of the engine on my '91 C-4 with electronic control of the HVAC. It has two ports, one that is connected by hose to engine vacuum, and the other connected by hose to the HVAC control module.
When I could not opt between defrost, vent, bi-level, and after some exploration, I bypassed this item with a short tube, thus furnishing engine vacuum to the HVAC module and everything works well.
QUESTION: What is the depicted item for, and what controls it?
Believe that would be the Fuel Vapor Canister Purge Valve Solenoid.
There are two vacuum fittings below the electrical connector, correct?
Ha! I bet you are RIGHT! Looks like I have some additional research to do, cuz I'm wondering why it affects vacuum to my HVAC. Yes, it does have two vacuum fittings below the electrical connector. In the picture, one of them is missing cuz I removed it to blow stuff out of the line. If you look at my picture, you'll see a bunch of little particles resembling cockroach droppings. The little valve -- valve, if that's what it is -- was full of 'em.
I'll post my findings -- if any -- here. Thanks for your thoughtful and on-point comment. Both a rarity for internet fora.
No. One line in one line out. No t’s. It just goes from a port on the TB to the vent valve then to a hard line under the coolant surge tank which goes back to the charcoal canister.
No. One line in one line out. No t’s. It just goes from a port on the TB to the vent valve then to a hard line under the coolant surge tank which goes back to the charcoal canister.
So then the OP just needs to have 'correct' routing or 'modify' it similarly to gain function and be sure vacuum is supplied to all components that require it!
Those "cockroach droppings" may be charcoal bits from the vapor canister. If so, that valve/solenoid is probably shot (stuck open). And, if you care, it won't help to replace that part as long as canister is leaking. All speculative, of course.
Mystery component
