Anyone had this problem? I have a constant vacuum pulling from my controller and I want to fix it, but seem they are by way of dinosaurs.

 

Year, model, engine, 2WD or 4WD? Service engine soon light on? What DTC's are in memory? Are you referring to the EVAP purge solenoid, the EVAP vent solenoid, or the 4WD actuator? What makes you think it's leaking? What are the symptoms?

 

hahah stupid of me

1995 4.3 4wd

the climate control/defroster/vent

I can turn it 5 different ways the still a vacuum leak. I took it apart and the diaphram looks ok

 

I see The HVAC is automatic climate control? Or is it manual? Does it have temperature degree markings on the dial?

Is the air flow constantly blowing on the windshield, (defrost)? Have you checked the vacuum lines under the hood going to the vacuum reservoir, (round plastic ball)?
Do you have a hand held vacuum pump/tester? http://www.mityvac.com/ Excellent tool for diagnosing HVAC vacuum problems.

 

manual control.

yes to all, but no hand held tester.

no, it is the switch itself.

no matter what way you turn it, nothing works, but it has vacuum from the engine.. so all i hear at the switch is vacuum..

then i found the temp. control switch/pot was broken also. Funny not one auto parts place has it, but JC whittney does!

 

If any of the vacuum actuators in the dash leak, (or a hose comes off) it will sound like it's leaking at the mode control switch. If you use a hand vacuum pump on each actuator, or at the vacuum connector on the back of the mode switch, you can make sure each diaphragm holds vacuum, and operates its respective blend door. There are 4 vacuum actuators, and two of them are dual position, (2 vacuum lines to it).

 

ok so I got a control unit of ebay and put it in replaced vacuum lines under the hood and still nothing. I even unplugged the battery and let the car reset incase there was some sort of reboot for the system.

I have good vacuum pull (it will stick to my tongue)

I still have no 4wd, BUT if i take that line off and plug it (to the 4wd) i am still stuck with just defrost. So i know it is not a vacuum leak that far down.

Spent 30 bucks on a book to find NO information at all

 

I know what you mean about the aftermarket shop manuals, they're a total waste of money. Get a GM factory "dealer issue" shop manual set. Ebay usually has them. They cover one year, and one model, about 3K pages.

As you can see below, I'm not an artist, and I never claimed to be one This is the vacuum routing under the hood. The only exception on your 95, is that the vacuum reservoir is not in the fender. It is a black plastic ball, about the size of a softball, either attached to the hood, or on the right inner fender. If there are any leaks, you'll have problems with HVAC and 4WD. If you unplug the vacuum line that goes to the dash from the vacuum tee, and apply vacuum to the line, (not the tee), it should hold vacuum indefinitely, in each mode switch position. If it doesn't, there's a leak in the dash. If each position holds vacuum, the problem is under the hood.

 

thanks capt.. I am really thinking it is dash. But I will buy a vacuum pump tomorrow

 

i have that hard line that goes in the firewall to the hvac i am guessing, next step is to look under the dash but the pedals and see whats up.

your diagram is spot on and yes, my reservoir is on the hood.