Ok i my dash vents (a/c vents) do not blow any air. I had them fixed last year and the check valve was cracked. well the one in there is still fine but they are not blowing again. Anyway I noticed when I used the defroster yesterday that I got a misfire around 2k no matter what gear. It was really strange. So know i am beginning to think that the reason the check valve has been breaking is because there is sometype of a vaccuum leak and this would also cause the mis and or rough idle. anyone else have this problem or any ideas on how to figure this out. I would like to have the vents work for more than a month. Plus it would be nice to take care of the miss. the car does not miss until the fans come on.

thanks miles

 

is the three way check valve on passenger side broken? you can put a two way on there and just not have a tube going to the vacuum canister. it still works fine.

 

no the last time the fans stopped working I replaced the valve because that is what the shop fixed the first time. when the fnas went out this time the valve that is in there is fine but fans no worky

 

Well, the fans will come on if you have a Service Engine light from the misfire. I'd definetely check for a vacuum leak....

 

You need to test for vacuum leaks.

 

ok thanks shoebox I will try that out maybe tommarrow if get a chance.

just to make sure i understand the directions
I unplug the line from the manifold and plug it back into the check valve from where I removed the line I am going to test. That is how i understand it anyway. what does it mean when you are applying the vaccuum to see if it holds, I dont understand this part.
thanks in advance

 

The meaning is that to test that section of hose to the manifold you have to apply vacuum at one end and plug the other.

You apply vacuum to it and whatever reading you pump it to, it should "hold"-no leaks, no drop in vacuum.