Dragonmaster wrote:Found this on GM's techlink forum:
quote: If you can find vacuum schematics a few years back you will see that they added a vacuum actuator to the case called a "slave" valve, it has a grey hose going to it from the control head.
BUT this is only supposed to exist with AUTO CLIMATE CONTROL!
A bad example is doc# 389165, it shows the hose and actuator I speak of but I can't find anything that shows operation for the "slave" door.
What happens on vehicles with C60 manual HVAC is that the door causes ambient air under pressure at the cowl to be forced through the heater core making it nice and toasty and cooking the driver's foot because the mode door rests in the "heat" position.
Open the glove box, lift up the wire hook and swing the door down. Now you will see right in front of you this actuator with the grey hose, take the grey hose off the vacuum actuator and stick a bolt in the end of it so it won't hiss or leak, tie it back so it won't rattle around and close the glove box.
You just fixed this concern, made the customer happy, flabbergasted your SM and if you think I am full of dookie, try all the other modes. They are TOTALLY unaffected by disconnecting that actuator, the heat is just as hot and the A/C is just as cold.
I think in the '96 manual comparing the vacuum scematics on C60 and whatever auto is on the utility you will see that the grey hose and the actuator are not supposed to exist on C60 manual HVAC vehicles.
I am not exactly sure what this "slave" door is supposed to do but I know when you turn the HVAC knob to Off it fries your feet.
I think someone sold them on the idea they could use one case for all units and neglected to mention that you'd have a few hundred thousand folks with burnt toes.
I thought TAC figured this out by now with someone's help I guess I never called and told them because I know how to fix it already.
I have done this to half a dozen customer's cars and they all leave happy as a lark.
Call me nuts if you want but that's how to fix it and althought it is "normal" (because ALL of them do it) it's still wrong.
Thought this was important enough and such an easy fix, that I'd add it here too.
The gray line that runs to the "Vac pot" in the upper center is the one I disconnected and plugged.