dctrouant1995

Alright I replaced everything in the control panel, everything works, but it only blows out the defroster vents, I think I found the culprit but have no idea what it is. It is locate right next to intake plenum on a TPI, has 3 vacuum lines going to it.. HELP. Its got the letter P on it and its underlined. One of the vacuum lines comes from the bottom of the plenum, I can't tell where the other one comes from, but it merges into the same vacuum line coming from heater control valve

jermdm

Its called a check valve. It keeps the vacuum ball in the driver side front fender from losing its vacuum when you accelerate or accelerate hard so your heater doesnt default to the defrost position.

dctrouant1995

I found that part, didn't help, but it was only 4 dollars and it needed to be replaced anyway. Do you know where the bottom vacuum line goes? Mine just pulled up and wasn't connected to anything

mantaguy

iTrader: (5)

It looks like the check valve for your window washer.

dctrouant1995

so could it be that vacuum ball thats causin my heater to stay on defrost?

sofakingdom

iTrader: (1)

Imagine a pressurized water system with a reservoir tank. The kind that has a diaphragm with a spring under it, such that when pressure is coming in, th espring gets compressed.

If the pressure to the house ever went away, the reservoir can supply water to the house. Problem is, water will go back UPSTREAM in the water pipe, out to everybody else's house, which won't last 10 seconds. Eh??

The solution is a check valve; only allows water to go one way. You put the check valve in the line between the source and the house, and you put the reservoir in parallel with the house plumbing, on the "down" side of the check valve.

That's what's in your hand, is the check valve. Works EXACTLY the same way as one in a water system wuold, except it allows vacuum to pass one way, rather than pressure. The vacuum ball is the reservoir. The idea is, when vacuum is high, the reservoir stores it up; but when engine vacuum goes away (driver's foot is on the floor) the vacuum stored in the ball still holds up the AC controls. The check valve keeps the vacuum from escaping back to the non-vacuumed intake manifold.

You need to inspect the ENTIRE vacuum plumbing system for the AC; the place it plugs into the motor, the check valve, the line that goes to the reservoir, and the line that goes to the control head.

dctrouant1995

sofakingkindom: Thanks! helped alot haha. Gotta put a power steering hose on today so I will check all the vacuum lines and everything

mantaguy

iTrader: (5)

I found that part no. in the parts catalog.P/N 14056648,Ck.HTR & A/C CONT.CRCONT VAC
New Part#: 15733271

dctrouant1995

where did you find it? I checked all the vacuum lines today, plugged the one from the cruise control (don't have cruise control anymore) and also plugged the line coming off the bottom of the check valve. Pretty much solved it. Thanks!

mantaguy

iTrader: (5)

http://www.kt-s.net/media/1982-1992_...ember_1992.pdf
It's in this pdf,you can download it.
The part no. listed for that valve has changed.I got the new no from
http://www.gmpartscenter.net/index.p...partnum=accept

dctrouant1995

Alright thanks, went ahead and ordered it from gm to have a back up one