OK y'all (southern US for you all).
Got the Air Conditioner working on the 1991 Coupe, however, now if you turn on the fan, it blows cold. Can not get any heat? Thermostat defective?

 

An easy place to begin is the heater valve. Is it working? First located it...buried behind the engine on the firewall, about in the middle.

Have a helper turn the temp control from cold to hot while you observe the valve. Does the lever arm on the valve move?

If not it might be stuck or it isn't being told to move. Pull the vacuum hose...any change? (no vacuum = open valve = heat)

Also, when you select max heat on the control knob does the air flow switch to the footwell vents? if so, the the system is at least recognizing that heat is being requested, even if it can't provide any at the moment.

Cheers
DD

 

Doug,
Even when I "hijack" a vacuum line and open the Heater Valve, still blows AC. When I turn the thermostat to 85 and slide the control to right it acts like it wants shut compressor off and will almost stall the car???????????

 

Doug, Also, is there a manual on this Delanier system to be had anywhere?
Do you happen to know what colors control what? Red is (appears to be) the main vacuum source, comes directly off intake manifold. Neutral seems to be the source over to the other 3 solenoids, then Green, Blue to the door controllers, but since there isn't enough room in there for my fat head they are hard to trace.
Also, there is another vacuum lead that comes in from intake that I don't have a clue where it connects and when I unbuttoned this thing it was just hanging loose, not connected, any idea what that might be.
I would like to have words with whoever went into this thing before and left this mess :-)

 

One other thing, if you don't mind, is there a way to test the 4 vacuum solenoids?

Thanx,
Glenn

 

Jaguar #43 Delanair Mk 3 Air conditioning unit manual, Language: English, Category: Owners manuals





I don't know the colors offhand....but be careful with a red vacuum supply. The ECU for the Marelli ignition uses a red vacuum supply tube

Cheers
DD

 

That link doesn't work, I guess. Sorry.

There ARE Delanair manuals out there. Just do a bit of Googling...make sure to look for the manuals for a Mk III or Mark 3 system.

Much of the same info is in the regular Jaguar service manuals.

Cheers
DD

 

Assuming the car runs fine the red vac tube is not the vac-to-engine-ECU line. So that makes it the Water valve vac supply. OTOH no vac should give lots of heat! Do upper and center flaps move if you request full heat? I would check the vac connections to the vac solenoid unit, sitting somwhere LH underneath the main unit., behind the lowermost part with control knobs and side vents and in front of the LH drain tube. Looking from the LH side the rearmost is the recirc vac solenoid (blue tube), the foremost is the water valve solenoid (red tube). RH the centre vent (blue) side vents (green) solenoid assy resides.

Moving between full heat and full cold you should hear the direct acting electric servo motors moving the blend flaps. If nothing moves the systemthinks it is asking for full cooling. Tell us what you find.

 

The neutral tube then is manifold vacuum?
Nothing moves when turned to full heat. Or back to cool. Doesn't matter if knob is in Auto or Manual.
Servo motors are above glove box toward center, yes? Neither operate I don't believe.
Should the elctric servo motors operate on their own electrically, or do they require vacuum to activate? If on their own electrically, shouldn't they function without vehicle running?
Sorry y'all, AC just isn't my thing. A whole new Elephant to be eaten one bite at a time. :-)

 

Glenn -

Have you read the article on the Delanair Mk III in 'the Book'? It will provide you with the schematic for the vacuum control line and give quite a bit of detail for troubleshooting no heat.

Kirby Palm's Jaguar XJ-S Help Book

Regarding your answer on whether you can troubleshoot the vacuum solenoids. Yes! Pull the solenoids (no easy feat) being sure to mark which end is connected to what vacuum line. Use a common 9V battery to short the ends. On a properly working solenoid you should hear a 'click' and be able to blow through the line. But failure of the solenoid to the coolant valve will result in max heat, vacuum closes it, so I woudn't start looking for faults there yet.

Not sure what you mean by the electric servo motors... The vacuum solenoids open vacuum to the individual vacuum actuators.

Initial thoughts are you should start looking at replacing the heater valve, which is a common failure item especially at this point in the car's life. Simple test, with the engine off disconnect it from the coolant lines and connect one end up to a garden hose with some hose clamps. Run water to it. Does water come freely out the other side? Nope? Then it's jammed shut and needs replacement... If yes, reconnect the coolant lines, disconnect the vacuum line to the heater valve, start her up and drive around until the engine's warm. If warm air is still not coming out, you've probably got a blocked up heater core or coolant line. Only if warm air does come out at that point would I start investigating the temperature sensors or ECU...

Cheers,

- Will

 

One thought before you get neck deep....

I've brought two MkIII systems back to life by taking a couple hours to clean all the little connector sockets and the main grounds.

On either side of the climate control case are 3-4 connectors....quite small with fine wires. A couple on the left side are up high and a bit hard to reach. The grounds are on the vertical dashboard supports on either side of the climate control case

Might give it a try....and poor connections will give confusing test results if it comes down to step by step troubleshooting

Cheers
DD

 

Read the neighbouring thread on AC nearly working: A very good writeup on the solenoids. And also on checking the servos which are purely electrical. With the engine off but ignition on they should whirr happily away when you move the selector from full cold to full warm and vice versa. Doug's tip on starting out by cleaning all the connectors is a good place to start. The Delanair is like so many british items from the day: Repairable forever but needs it

 

Where is the vacuum reservoir supposed to be located?

 

IIRC in the engine bay beneath a cover on the passenger side, in fact where the pedals go when the drive is on the other side (LHD/RHD).

 

Will, OK, finally had time to troubleshoot further. Heater valve opens when turned to heat, not heater valve. All Vacuum solenoids are functional (tested with 9v bat) so no defective solenoids and they function in accordance with demand, kinda.

Still only blows AC cold air out of vents? (AC is unfortunately working perfectly and Winter is coming.) Compressor does not kick off when heat is demanded either, compressor does kick off on my other car so assuming that is default. Anyway, still no heat.

 

OK, finally had time to troubleshoot further. Heater valve opens when turned to heat, not heater valve. All Vacuum solenoids are functional (tested with 9v bat) so no defective solenoids and they function in accordance with demand, kinda.

Still only blows AC cold air out of vents? (AC is unfortunately working perfectly and Winter is coming.) Compressor does not kick off when heat is demanded either, compressor does kick off on my other car so assuming that is default. Anyway, still no heat.

 

Please explain what you're saying :-)



Normal for comp to stay engaged when heat is called for. All incoming air is cooled first, then heated as required.

Cheers
DD

 

By the way y'all, the tip about pulling fan motor fuses and testing helped a great deal, don't remember which of you gave that tip, but thnx.

 

OK, so, if Heater Valve is opening, heat should be available, yes?

 

Could it be a clogged heater core????