VZ manual aircon/heater problem

[bcw61]

I know that this problem has been raised in the VT Commodore forum, but I have an issue with my aircon/heater system, where the air vent switches over to full demist under heavy acceleration. Further, the floor/demist position doesn't seem to be working correctly, as all the air comes out the demist vents. Any suggestions?

Also, someone posted a diagram of a HVAC unit on these forums, but it seems to be a slightly different unit to my VZ HVAC, as the vacuum solenoid pack doesn't seem to be fitted adjacent to the blower housing. Having a quick look, the colored vacuum lines to the actuators appear to disappear to the top front of the HVAC unit. Can someone please confirm the location of the vacuum solenoid pack on the VZ HVAC unit, and what dash items have to be removed to gain access to the vacuum solenoid pack & vacuum actuators?

TIA

[jaisvz]

Hi TIA,

i also have this problem since putting a blower onto my engine.
dont know if it was caused by that, but it has had me scratching my head for months

[bcw61]

Just an update if anyone is interested, I have found the cause of the problem. One of the diaphragms in the demist/foot vacuum actuator has completely torn. Unfortunately, Holden have nil stocks of new vacuum actuators Aust wide - with new stock apparently not due until Nov.

[andyman]

jaisvz is also probably because of the lack of vacuum in his motor when the throttle is open,

maybe a seperate vacuum pump attached to the hvac unit vacuum line would work better for you