HOW COME I get hot air out of the demister vents and dash side vents when I select cold on the aircon? I get cold air at my feet.
1990 build V12 Marelli car

 

Go to post #19 in this thread.....

https://www.jaguarforums.com/forum/x...-manual-83961/

....where you can open up the manual for your Delanair Mk III climate control


I can't think of a known, common cause for the problem you describe. You'll have to do some testing/testing/observing to figure why the system isn't changing modes.

It might be a case of poor grounds and dirty connections.....so track all of those down (look for the thin wires and tiny connectors) and make sure they're clean because not of the tests in the manual are valid if the connections are poor.

Others will chime in

Cheers
DD

 

On mine there is a slider at the base of the controls that changes the temperature of the upper vents; I think that it is left for hot and right for cold.

 

There's no vacuum at heater tap, therefore its not shutting off, further investigations pending...

 

Steve yes I have that but makes no difference

 

That slide control has a 'trimming' effect only. After the cabin temp and climate control have stabilized the slide control can be used to vary upper vs. lower outlet temps by a few degrees. It gives just a very subtle change.

Cheers
DD

 

ok found I have no vacuum at the heater control valve. I reckon this is part of the issue as well. I can blow/suck through the vac line with little restriction. I have Vac at the main line after the non return valve from the engine. reading through various posts and the Book I've found instructions where to find the vacuum solenoids in a LHD car, I assumed they're on the opposite síde in a RHD car? I've got the glove box out and the footwell trim out and cant find the vac solenoids or reservoir anywhere. what else needs to come ou/where are these bits?

 

Does this help at all?

Air Conditioning Vacuum Solenoid and Pipes - Parts For XJS from (V)139052 to (V)179736 | Jaguar Heritage Parts UK

As I recall you'll find these in the area directly behind the radio. Should be the same LHD vs RHD

Cheers
DD

 

Just found a great post by Sarc in 2012 - found the solenoids, now wheres that damn reservoir??

 

So...where are they?



I dunno. Tucked up in one of the fenders behind a front wheel?


Cheers
DD

 

In a RHD car the reservoir is in cavity above L/H footwell where brake pedal would be on LHD car. Access from engine bay as it is attached to blanking plate/ABS pup mount. The integrity of the res. can be tested from the hoses into and out of it, much easier than pulling the thing out for no gain.
I would start at the heater valve and work back. Connect your vac line to valve then go inside and suck on solonoid end and so on. Those little elbows on the solonoids do perish and crack.

 

Solonoids are behind forward console extensions. Two each side. Remove screws in footwell vent.
Reservoir is in unused brake pedal assy aperture depending on drive side.

 

[QUOTE=Doug;1405250]So...where are they?



They are laid out two per side, as Sarc advises you have to remove the foot vent plastic ducting things and the solenoids are behind these. his can be done without removing the centre console if you're tricky

 

OK I've found a dud solenoid LHS forward isn't this the recirc solenoid?
the water valve is the rearmost on this side.
I'm also getting no voltage to the centre vent solenoid on the RHS after the demister vent closes. I have the ground but no 12v which is fed direct from the ECM.

 

Blue line is recirc. and red is heater valve.
It's not as simple as probing for the required voltage at the solenoid, especially regarding the centre vent which only gets instruction to open in limited conditions.
You may need to run through the ecm pin test procedure.

 

In my experience, FWIW, the best place to begin is by cleaning all the connectors ...and the two grounds. Sometimes that's all it takes to solve the problem but, if nothing else, the test results are suspect if the connections and grounds are suspect.

At least open up one or two of the connectors. If one or two are loaded with green corrosion you can pretty safely assume they all are. I've worked on only two of these systems but, in both cases, all the connections were fouled

Cheers
DD

 

Hi all, from what I read, the centre vent is supposed to open in the Full Cool setting, I assume this occurs with RH control set to NORM or HIGH and the LH control set to 65F and manual? I have no evidence so far of any corrosion and I do have a good ground on the solenoid. everything looks really clean
I haven't found the ECM pin test procedure yet, czn someone point me in the right direction?


Cheers

 

Go to this thread....

https://www.jaguarforums.com/forum/x...-manual-83961/

....and then to post #19. There'll you'll find the manual with all the tests


Cheers
DD

 

Right!

Although if the cabin temp is hot enough you won't need to go to manual

Cheers
DD

 

Thanks Doug I've on the computer for hours, looking in all the wrong spots obviously! I reckon I found it just as you were typing your post! anyway it's printing now and i'll be doing some testing this afternoon