Just got the truck this week. I put a new A/C Compressor on it because the previous owner did not have one on there. I had some issues that are now fixed, but I am still having one. While driving, as I push the throttle, the air blowing through the dash stops and it starts blowing from the defrost vent under the windshield? Is there a simple fix for this, or is it going to have to go to the shop? Thanks for all info.

 

It's called "wild vents" in these parts. You can search for that to read all of the tales if you'd like. The most common fix is the vacuum check valve on the passenger side of the intake manifold, but it's not certain. Any vacuum leak on the upstream side of the valve could give you grief, too.

The part's eight or nine bucks at the dealership. Auto parts stores don't carry suitable substitutes.

Welcome to the forum!

 

Thanks for the welcome. I will try that Monday.

 

You can test the thing by pulling it out and gently blowing through it. If it pops closed in one direction and doesn't leak when closed, it's okay. If it leaks, or doesn't close at all, it's a goner.

If the one next to the manifold is apparently okay, there's another upstream of that and closer to the firewall near a little plastic vacuum manifold. Same part, same test.

If neither is failed, though unlikely, it's time to break out the vacuum pump and hunt down the leak. There's quite a lot of vacuum plumbing under the dash, and some vacuum motors, too.

Good luck, and I hope the quick/easy/cheap fix does it for you.

 

Well, its fixed. The valve just before the elbow into the intake was the culprit. Now to fix the dash... is there a way to put in a dash from a newer model without too much more trouble?