IcemanG17

Okay
I replaced the blue/black vaccuum check valve already & am waiting for a new 4 way "T" (the old one seemed to loose)....I would check the white hose that attaches to the 4 way "T" and it does not hold vaccuum at all. So I checked the flappy soleniod on the drivers side cam belt cover. The good news is the black line on the bottom holds vaccuum. I checked for flappy movement and the flappy starts to move almost instantly and is fully open at just 10 inches of vaccuum. The white line that goes into the intake (& hopefully back to the 4 way "T") does not hold vaccuum at all? Is this normal? I know there is some leaks in the HVAC system but don't understand why the white line doesn't hold any vaccuum?
Thanks
Brian

deliriousga

While you're waiting for your new 4-way connector it can be "rigged" to work. My A/C was clicking all the time (recirc flap) and would turn warm sometimes. Last weekend I tested everything and cleaned out the check valve. Then I put tune-up grease on the outside of the tubes and pushed them into the 4-way connector and zip tied the connections that felt loose. I used tune-up grease because it should be safe for the rubber even though I'm replacing it soon. The A/C is working perfectly now and I'll order the 4-way connector the next time I need something shipped.

I'll check the white line you're talking about on mine and see if it holds vacuum and get back to you in a few minutes.

deliriousga

The black one in mine holds 13 in. with the car running and the A/C on full blast. With the car stopped using the pump to test, it holds whatever level I pump it to.

The white one also holds 13 in. with the car running and the A/C on full blast. With the car stopped using the pump to test, it does not hold any vacuum.

IcemanG17

John
Thanks for the detailed reply......I tested mine with the car off. The car typically holds 10in of vaccuum with the car on. I'm guessing that the white line does not hold vaccuum with the car off as part of the solenoid that controls the flappy? So it appears this is normal?

Brian

deliriousga

I think that's right. When I was checking things out for the A/C problem, I had no vacuum on a couple of the tubes when the engine was off and the controls those tubes were for work fine. I'm going to try to remember to use the cruise control on the way in tomorrow to see if it holds now. I'll also be checking the rest of the vacuum tubes inside the dash this weekend to make sure everything is up to snuff. If there are any other tubes that don't hold a vacuum when the engine is off I'll let you know for comparison.

IcemanG17

John
The good news is my cruise control works fine....so that means the brown line from the "T" is fine...now I just need to track down which actuator is leaking inside the dash....that will be a bit harder than just checking under the hood!
Brian

IcemanG17

John
Okay a little more testing today after work came up with these results:

Black line will hold 20in of vaccuum and instantly start declining to zero in about 20 seconds
The white line (when capped at the solenoid end) holds vaccum perfectly
The black line that goes from the solenoid to the flappy holds vaccuum perfectly (very good!)
The 4 way "T" hold vaccuum perfectly when the black and white lines are "capped" (by my fingers)
And the brown line that goes to the vaccuum tank also holds vaccuum perfectly...but takes forever to pump up!
Removing the black (HVAC) line at idle and testing the "T" from there will hold a steady 14.5" of vaccuum at idle (only an unsteady 10 before replacing the blue/black check valve).

So it appears everything under the hood is in order...on to the dash HVAC for more diagnosis!
Brian

deliriousga

Is yours an S4? I'm assuming it is from the pic in your avatar.

Just wondering also if you're having any problems or just a routine check-up? I didn't see a specific problem mentioned before so I wasn't sure.

Mine is close to the same when the black (HVAC) line is pulled and I tested the connector from there. 17in. steady at idle and I had 10in. somewhat steady before I cleaned the check valve. Testing at the base of the check valve where it plugs into the 4-way connector I get 22in. steady and it was 15 before I cleaned it out.

I have about 13in. steady at the heater valve at idle.

I need to re-test the other connections so I can write them down for comparison next year so I guess I'll be doing that Saturday along with under the dash.

IcemanG17

John
88S4....standard problems with non functioning HVAC actuators...the footwell does not open....plus I'm imagining there are other leaky actuators in there too! I get exactly zero at the heater valve! Which is why I did the zip tie fix for the summer! 22in seems like quite a bit, but I was testing my car cold...which might explain why its lower than your numbers.
Brian