Heater Issues

[cromanyak]

My heater in my 88 only blows through the defrost vent no matter what you have it set to. Does anyone know why it would do this?

[Eagle]

Vacuum leak.

 

The flappers in the dashboard are controlled by vacuum. They default to the defrost position if vacuum is lost. The most likely problem spot is where the vacuum lines run under the battery tray to the reservoir, which is (if your truck is stock) located on the right front, behind the bumper.

 

The reservoir is a plastic sphere or suasage, and it's also possible that the reservoir has been cracked, which would also result in loss of vacuum.

[cromanyak]

That canister is gone on mine. There's 2 hoses that run under the battery tray a larger one, maybe 1/4 or 1/2 inch and a small one. Are those the only two that hook to the canister? I guess I'll need to post a want ad in the classifieds.

[jaekl]

You can get new reservoirs, but be careful. I found the best price, about $8.00 delivered from Jeep 4x4 Center. The problem is there is only one fitting. Is it for a later model? Not worth it to send back.

[cromanyak]

It's an 88 w/ the 4.0

[cromanyak]

Do you know what the part # was?

[feerocknok]

You can make one out of a piece of pipe with pipe caps on both ends and holes drilled for plastic fittings. Hard to describe, but it's just like a little pill that's sealed up.

[cromanyak]

Does anyone happen to have a pic of one? Or even better dimensions?

[jtdesigns]

I swear that part is the same off 4x4 s-10 blazers. I'd have to double check the blazers but they look identical.