Air-conditioning problem

[seldo]

Just did a 600km round trip over the weekend in my VY Senator, and I find that when I accelerate (and engine vacuum drops) the air-cond seems to suddenly switch to defrost and blows hot-air, and as soon as I back-off, it reverts to cold.
Any clues anyone?
Thanks
Dave

[QIKMIK]

Yep. You've clearly had the old girl too long and need one of them new, fandangled LSA Senators

Mick

[Micks]

If that doesn't tickle your fancy, probably looking at perished vac line/faulty switch/actuator.

[Woodchukka]

Is there a one way valve inline to hold vacuum in the system during periods of higher manifold pressure?

[IJ.]

Is there a one way valve inline to hold vacuum in the system during periods of higher manifold pressure?

From memory there's a small vacc reservoir mounted to the side of the box under the dash for that Woody.

[Malus]

I had this same issue with my VT Berlina.
I replaced the vacuum solenoids behind the glovebox and all was well for a few months, then the same thing happened again. I then replaced the clear rubber manifold that connects all the vacuum solenoids to the vacuum reservoir, this again worked for a while then something let go again. I got sick of loosing aircon on 40C days while driving up and down hilly roads, so I sold the car and bought a brand new VE SS ute. Best decision I ever made Actually, scratch that, trading the SS for a E3 Maloo was the best decision :P

[seldo]

Yep. You've clearly had the old girl too long and need one of them new, fandangled LSA Senators

Mick

Ahh yes grasshopper....But I'm a self-funded retiree, and I still love the old girl (and the missus too...) so can't justify throwing a heap of money to replace it with something that is only marginally better in some ways....and it's still only done 145ks

[seldo]

From memory there's a small vacc reservoir mounted to the side of the box under the dash for that Woody.

Hmm- that sounds close to the money. Should have guessed that you might be the man with the answer Thanks IJ. Any other thoughts?

[IJ.]

Sorry Seldo not really, only that I'd check all the basics then all the vacuum lines, there's a 1 way just out of the firewall in the engine bay as well..

[Micks]

Failing that may have a ruptured vac tank?

[Jag530G]

The default setting for the climate control if it loses vacuum is windscreen defrost. Think in terms of roadworthy safety and design, the car should always be able to defrost the windscreen, cooling passengers is secondary.

Most likely candidates will be the vacuum actuators on the heater/Evap box (bit painful as means more dash disassembly), or vacuum solenoids (easier as they are just behind the glovebox).

I pulled the dash out of Monaro to replace the evaporator/core, if you don't have to go as far as pulling the H/E box out it isn't a difficulty job as don't have to de/re gas the A/C, jsut lots of screws to undo basically.

Cheers, Matthew

[seldo]

Had the air-cond fixed....again....
And cheap too....again....
Replaced both vacuum actuators and heater tap, and while they were at it, said that the non-OE compressor fitted by the last mob was crap, so replaced that with an OE one. As well as, of course, TX valve, receiver-drier etc...
I must admit that the air is colder than it's been for as long as I recall, so despite the finan$ial pain, it was worth-while.
I must say that the air has been the only real problem I've ever had, and I have spent about $2k every 3 years on it, so I hope this will see the end of the problem.
Thanks for the input peoples

[Micks]

Is always a good investment to get it done right, bet your glad it's all sorted for Summer

[seldo]

Is always a good investment to get it done right, bet your glad it's all sorted for Summer

Yes - it's good to get it right. And especially as up here in God's own country we run it all year round.

[Micks]

Too right you are very close