Hi All,
Please rest assured (I think) I have read just about every HVAC thread out there on the internet and scoured the workshop manual. At this point I feel I (mostly) understand how the HVAC system works and we have tried to fix it repeatedly. But now we are at the point where we need help from the experts please.

Some context.
Vacuum in the system as a whole is fine, cruise works and we bought a vacuum pump to test just about every orifice we could stick it in.
HVAC controls have been removed, twice, and cleaned thoroughly as per the excellent Utube video by WQT. This seemed to help a little.
The fan works correctly on all settings.

What is happening at the moment? - on fan setting 1 the directional **** seems to work and air comes from the different vents. However, there still seems to be too much air coming from the side defrost vents.
But, as soon as the fan **** is moved to 2 or above you hear, what I believe to be, the defrost door go “whomp” and air only then comes from the side defrost vents. There is no air from the screen vent.
Moving the control **** to the feet setting does direct some flow to the feet but not much. None of the other control settings make any difference on fan setting 2.

I think we are now at the point of having to remove the dash to get to the actuators to test them (can the actuators be accessed without removing the dash? Before we do this it would be great to have views on what the issue could be, personal experiences from those who have done this job and as many pictures of the vacuum routing for the actuators and what the various colours do.

Thanks for reading this far. I will update this thread with all our trials, errors and findings.

 

Sounds like a stuck or leaking defrost door actuator or a vacuum line issue inside the dash. The "whomp" noise when increasing fan speed suggests the defrost door is getting pulled shut by vacuum. You *can* access some actuators without full dash removal check behind the glovebox first. The main culprit is often the defrost actuator or its vacuum line. Double-check the vacuum harness near the HVAC controls toosometimes it cracks. If all else fails, the dash might need to come out.

 

Thanks Roberto. I agree with you. Which actuator is the defrost, is it one of the ones on the side of the unit or the other one which I think won’t be accessible without the dash out?

 

Answered my own question above.
This diagram from the FWM shows the defrost actuator as the centre one on the end of the HVAC unit.

This schematic shows the defrost actuator having yellow and blue lines.



This image is the best I can find showing the placement of the actuators. If the HVAC unit is the same on LHD and RHD drive models then the actuator access on a RHD might more awkward from the pedal side.


This image shows the 4th actuator(?)


Please excuse the size of the pictures, I’m trying to figure out how to resize them.