R134 retro'd A/C cools well until engine heats up, but heater valve never shuts off completely, so hot air comes in after a while, I had to jam a 5/8" rubber pipe into center vent to open it, defrost flap never shuts off completely, slightly fast idle (1000) rpm even though AUX air valve is all the way in. I am certain there's a vacuum leak, but where is that vacuum bottle (pig?) how do I remove it, and is there a recommended way to track down vacuum leaks, vacuum hose routing diagram, troubleshooting procedure on the Delinair III? i.e. what is the normal reading for vacuum out of the manifold? solenoids?
Also, what should I use/avoid for vacuum hose? Gauges? Pump?

 

I bought a hand vacuum pump/brake bleeder. I took the vacuum line with the white stripe located above the brake pump on the firewall loose and pumped several times.
The hose going from the union back towards the drivers side doesn't leak down. The one going back into the interior (footwell?) has a pretty bad leak.
Is that the vacuum supply into the Delinair system? Or does that line go somewhere else?
I still cannot find the vacuum reservoir, nor where it connects to the intake manifold.

 

Goes to post #8 of this thread. There's a link to a good Mk III manual:

https://www.jaguarforums.com/forum/x...roblem-129541/

It mostly covers electrical aspects of the system but there are a couple blurbs about the vacuum systems.

Meanwhile I'll try to find a good vacuum diagram for the Mk III

As far as I recall any vacuum hose going into the cabin will be related to the climate control except the brightly colored one (red, I think) that goes to the ECU for the marelli ignition

Cheers
DD

 

Here are a couple vacuum diagrams for MK III systems....but for later models than yours. Not sure if that helps or hurts

Cheers
DD

 

I found this in XJS MkIII Climate Control.pdf in another post.
The vacuum reservoir is located behind the front bulkhead right closing panel.
Sorry, I still cannot find this part, so I cannot test it or the lines going to it.
Where is it located? How do I access it? any special tools or gadgets needed?
Please respond!

 

I have the JTIS CD, but it won't work on Win7 or Win10.
Does JTIS show the location of the vacuum reservoir?
Please respond.

 

This item is accessed in the engine bay. It is in the position that the pedal box would be in if your car was steered from the other side. If you look underneath whatever is on top of there on your car, you will see a square hatch, which when unbolted reveals the reservoir.

 

Finally found this From JTIS:
Reservac tank - Remove and refit 70.50.04
Removing
1 Remove right-hand front wheel.
2 Remove screws securing lower edge of
diaphragm panel to front skirt panel.
3 Prise free plastic studs securing top of
diaphram panel to inner wing.
4 Remove diaphragm panel from wheel arch.
5 Remove bolt securing clamp around waist of reservac.
6 Slacken clip securing Vacuum hose to tank.
7 Ease reservac tank clear of clamp and disengage from vacuum pipe.
8 Lift reservac from car.
Retrofitting
Reverse operations 1 to 8.

All this MUST be for an earlier model. Mine has no such panel under the fender to access this area.

I found the (USA) passenger side square hatch plate, held on to the firewall with 4 large bolts.
There is a black vacuum tube going into the rubber tube thru the middle of this plate. this one is leaking badly.
there is a hose going into the tank, and the other tube goes out to the Delinair III system. I will take the dash apart next and try to diagnose this leak from under there. Does anybody have any photos of this vacuum hose going from the reservoir tank to the Delinair III system? The diagram above shows this hose going to a T, then white stripe hoses to 2 more T's.
I'll try and post photos of the results when I have found the leak(s) and the results for the heater valve, A/C system vacuum servos/vent flaps and the high idle speed/AAV problems.