Fan issue

julian · Post by **julian** » Wed Dec 26, 2007 10:14 pm

My in cabin air con/fan has a problem.
When I reach speeds above aproximately 90kmh the fan progressively moves air coming out of the face vents and moves it down onto the feet.
End result on a hot day is passengers get cold feet but everything else is warm.
Whassa-goin-on?
Temporary fix appreciated as I have a 200km drive tomorrow morning...

sven '2' · Post by **sven '2'** » Wed Dec 26, 2007 10:38 pm

the HVAC controls are driven from the vacum system...maybe start there?

I seem to remember when doing dash swaps, testing the HVAC system buying turning on the fan it always blew towards the feet area. Start the motor, ie create vacum, then the directions would work.

Maybe try and clamp the vac supply line?

SUBYDAZZ · Post by **SUBYDAZZ** » Thu Dec 27, 2007 1:09 pm

Is it coming out on feet only, or feet and screen?

Gannon · Post by **Gannon** » Thu Dec 27, 2007 2:12 pm

The vac is provided by the engine vaccum.

You may have a split in one of the vac lines and as you are losing some vac pressure.

As car speed increases, so does engine load and thus manifold vac decreases and you are losing more vac through the split than the engine can supply.

Does the air redirect its self if you decelerate/ take your foot off the accelerator?

timmo · Post by **timmo** » Thu Dec 27, 2007 4:42 pm

yeah when theres no vac the feet vents is the only one open. Maybe the little vac tank behind the drivers side shock tower has a leak. Dunno why else it would be a progressive thing, usually everything eitehr works or it doesnt. But i guess you should check you didnt disturb a hose when hunting for your a/c problem

timmo

SUBYDAZZ · Post by **SUBYDAZZ** » Thu Dec 27, 2007 7:29 pm

OK, well I understood that when no vac is available that the screen or screen/feet should be the only one to have air directed to it - safety feature for defogging etc.

Gremlins · Post by **Gremlins** » Fri Dec 28, 2007 8:20 am

Yeah sounds like the system is loosing vacuum, interesting though that it is only doing it above 90km/h. Not sure how long the vacuum reserve will last on prolonged periods of turbo boost, but I would think it unlikely to be continually on boost at 90km/h unless you're towing a trailer or have a strong head wind. The vacuum canister on the import turbo L is on the firewall on the passengers side near where the aircon plumbing goes through into the cabin. The vacuum canister is black with two small rubber hoses attached to the top of it, one hose goes back to the intake (T's in near the boost sensor switches from memory) and the other goes off into the cabin to the switches on the dash that control the air vents. Follow the small hoses from the canister (in both directions) and check for any splits. The hoses typically split where they attach to something and are expanded to slide over the fitting. Will be a PITA if the problem is up near the switches in the dash as I think the dash surround needs to come off to get to the switches on that side, but it sounds like the problem is more likely to be before it gets to the switches.

julian · Post by **julian** » Fri Dec 28, 2007 6:02 pm

Suparoo wrote: Does the air redirect its self if you decelerate/ take your foot off the accelerator?

Hit the nail on the head right there!
When I take my foot off the throttle it comes back on the face...
Will start looking where you suggest Gremlins.
Cheers