Vx commodore AC vacuum leak

[max101cfh]

Hi I know this has been asked heaps of times but just in case, i have a a vx v6 equipe non climate control, and I have a vacuum leak Im not sure where it's coming from. When AC is on and it's under load it goes to demist, but if I have the heater on instead nothing happens it stays normal, I checked and replaced the hose and valve at the back of the engine and it's the still the same. I'm assuming it's either the hose from the vacuum tank to the engine bay or the vacuum tank itself. Anyway to test the vacuum tank. Any help would be appreciated ty

 

[lout]

this will most likely be a faulty blend door solenoid
thanks to an old member galahs
You can test the actuators once removed from the car by:
- Push in the plunger all the way and hold
- place your finger over the rear and side air port.
- stop pushing in the plunger as it should now remain held in by the vacuum pressure. If it doesn't it has a leak.
- release your finger from the side air port
- the plunger should move out to a half way position and stop. If it continues all the way it has a leak. (This is the step mine failed. It slowly extended all the way out)

remove finger from end port, plunger should move fully out
most common is the one next to your left foot with pink and orange hoses
this pic shows hvac assembly upside down
there is a 3rd one not shown
unclip arm from door
undo one phillips head screw
pull solenoid straight out, rear is clipped in
note orientation of hoses

 

[max101cfh]

this will most likely be a faulty blend door solenoid
thanks to an old member galahs
You can test the actuators once removed from the car by:
- Push in the plunger all the way and hold
- place your finger over the rear and side air port.
- stop pushing in the plunger as it should now remain held in by the vacuum pressure. If it doesn't it has a leak.
- release your finger from the side air port
- the plunger should move out to a half way position and stop. If it continues all the way it has a leak. (This is the step mine failed. It slowly extended all the way out)

remove finger from end port, plunger should move fully out
most common is the one next to your left foot with pink and orange hoses
this pic shows hvac assembly upside down
there is a 3rd one not shown
unclip arm from door
undo one phillips head screw
pull solenoid straight out, rear is clipped in
note orientation of hoses
View attachment 264501

I don't think it's the actuators (I will double check with the method you described) as the heater runs fine at any driving speed. It's only when the AC is on, that why I'm thinking it's possibly the vacuum tank. Would you know how test the tank by any chance. Also what is a blend door solenoid and where is it

 

[lout]

blend door solenoids are the white canisters in the photos
your symptoms 100% match a faulty solenoid
you dont usually notice with the heater, but it will still change from face to demist if you floor it
with no vacuum it defaults to heat and windscreen
so if you have cold on your face and then suddenly heat you notice it

 

[max101cfh]

blend door solenoids are the white canisters in the photos
your symptoms 100% match a faulty solenoid
you dont usually notice with the heater, but it will still change from face to demist if you floor it
with no vacuum it defaults to heat and windscreen
so if you have cold on your face and then suddenly heat you notice it.

Do you mean the actuators or vacuum solenoid. And it's stays cold when you floor it just stays to demist (still cold), the heater part I was talking about is when I actually turn the heater on to test if it does the same thing as when the AC Is on which it doesn't

 

[lout]

the little white canisters have 2 rubber diaphragms inside which split and leak
when you have high enough engine vacuum it can overcome this leak
but when you go uphill or floor it your engine vacuum decreases
and the canisters quickly deplete the vacuum in the tank

 

[max101cfh]

the little white canisters have 2 rubber diaphragms inside which split and leak
when you have high enough engine vacuum it can overcome this leak
but when you go uphill or floor it your engine vacuum decreases
and the canisters quickly deplete the vacuum in the tank

They both are holding vacuum, I done the test you to me and they don't move until I release where the vac lines are

 

[lout]

you will need to get a mityvac and go through the whole system
diagram i showed is for climate, but non-climate is the same except a rotary switch instead of solenoid pack

 

[max101cfh]

How do you use a mityvac on the system?
And where is the rotory switch, is that on the controls

 

[lout]

the temp selector and position switch are rotary switches
you will have to test each hose until you find one or more that does not hold vacuum
it may be the recirc solenoid which is hard to get to