AU vacuum tank

[sunnyhill]

Can anyone tell me EXACTLY where the vacuum reservoir which services the internal vents is located? As soon as pick up speed on the road the a/c vents close down, back off on the throttle and it returns. A vacuum problem but where is the booster tank?

[TE029]

This is normally a symptom of a blown intake manifold gasket,
Upon accelerating the vents switch to screen/demist when off throttle (max Vacuum) the vents return to normal setting,
Try with the car running spraying some WD40 or similar where the manifold mates up to the cylinder head, If the idle smooths or increases then the gasket is kaput...

[mik]

check all vacuum hoses too, don`t forget the heater tap under the inlet manifold.

[JC]

Under WOT, it is normal for the A/C to turn off - you didn't mention that picking up speed was under WOT, but thought I'd throw that in anyway.

[greenguzzler]

Hey JC,
Is that for the I6 and V8 or just common to I6's. My V8 Fairlane did that going up Bulli Pass south of Sydney a few months ago but hasnt ever done it since?
Thanks Pete.

[TE029]

Correct me if i am wrong, But i thought one of the standard features of (late model) falcon Ac on any motor was on full throttle the ac compressor clutch releases... Hence no drag...
You dont encounter it very often cause if the AC is not cycling at the time you dont even notice,

[sooty43]

The vac. tank is a piece of steel tube under the dash. Check for leaks with a vac. gauge placed in the line where it comes out of the bulkhead. If everything tests OK and it runs out of vac.and cuts off the AC. you can make an extra vac. tank out of a bit of exhaust pipe with welded ends. You strap it to the chassis with large hose clips and run its vac.line into the main vac.line doubling the volume of the system. This method cured my AU wagon of running out of AC. in summer inQLD towing a boat over the mountains where one is putting the foot down most of the way.

[sunnyhill]

Thanks sooty43, does the vac. line come through the bulkhead behind the screen washer tank? There is about a 5mm line there and I think it is even branded "vacuum supply".