HVAC Update,
I think I have nailed the ventilation to the demister issue when under acceleration,
I did a bit more research and found an old thread on JC’s on the very thing,
It appears the Actuator that is on the drivers side is the culprit,
The internal diaphragm has possibly split, as it’s partially active when the air is directed to the dash vents, which reducing the vacuum in the whole system to leak out,
so when you accelerate , the manifold pressure is reduced, being it is already leaking vacuum via the faulty diaphragm, so the remainder of the vacuum leaks,
This coursing the HVAC system to release the actuator to its home position, which is the demister vents.
The cost of the fix was $13 from the wrecker,
So I figured, I have 2 cars with climate control,
So a purchase 4 of them.
Interesting enough, when you remove the actuator, a little manual test to check if it’s faulty, push the arm in, and seal both vac ports with 2 fingers, if the arm moves out all the way it’s faulty,
If the arm remains in,
it’s not faulty.
Remove your finger on the back port and it should move approx. half way out,
Then remove your finger from the side port, and it will move to the home position.
That indicates the centre diaphragm is ok.
To remove the said actuator,
drop down the fuse panel under the drivers side, and carefully unclip it.
Remove the 2 screws on the side panel for the dash/console, and unclip that from the console,
You will now see the offending actuator,
There is 2 screws that secure it,
You don’t need to worry about the back one,
Use a right angle Phillips head screw driver,
Or what I did, is use a mini 1/4 drive ratchet that has an adaptor that can fit a Phillips head bit in it,
Removed the screw and a quick tug on the actuator forward will remove it,
But remember the “pink vac line goes to the back, the orange vac line goes to the side”,
Position the replacement one correctly and slide it under the rear screw, and push it into position then install the securing screw,
The rest is straight forward.
Then it’s ready to road test it.
while I had the tools out, I decided to clean the HVAC fan, then it got even more busier,
I then got my hand up onto the air chamber and felt leaves and crap in there, I removed the fan resistor so I could poke the vac hose through there, so I vac’d them out, then had a look above the fan, and the wire gauze was covered in leaves,
So it was off with the trim on the wipers, then the wipers, then the lower screen/ventilation moulding,
And that area was chock a block with leaves and crud, possibly from since new, possibly the cause of the smell of rotting leaves.
So I removed most of them by hand, then vac’d the rest, washed the area down with car wash, and re-assembled everything,
I did notice the fan was delivering more air, as there is no restriction at the inlet under the windscreen,
and the ventilation smells better.
There is a cabin filter that fits the said inlet, I think I read it’s a Volvo part.
But maybe next time for that project.