Some folks here may recall the various threads I have started here regarding my struggles with the climate control system on my MY94 XJ6.
In the last thread I had reported that changing the DBC10009 relay I had good reliable climate control operation.
However even though I have reliable climate control of the fans in the car, I still have no detectable heat flowing into the car.
I have checked over the past week or two the inlet and outlet hoses for the heater core.
I thought I could detect by feeling the hoses that the inlet hose was much warmer than the outlet hose leading me to believe that the heater core could be clogged up.
So yesterday I partially drained the cooling system and after much struggling I was able to remove the inlet and outlet hoses from the core connections on the firewall.
I then used a hose from my house water supply to inject water under pressure into the outlet of the heater core.
When I did this I had a kink in the garden hose I was using to do this with and when I leaned over to straighten out the kink I missed the actual first flow results through the heater core.
However I did hear a sort of "plop" and then when I turned to look at the water flow through the heater core in the reverse direction, it looked really good with a strong flow of water passing through the heater core and flowing out of the normal inlet connection on the heater core.
So thinking I had a positive result here, I put the hoses back on the heater core connections, filled up the cooling system again, and pilled the dog into the car so we could go for a ride to enjoy the fine heating system in the car.

Unfortunately after driving around for some time with the heater controls set for heat and the fans on medium I STILL HAD NO HEAT! ARGH!
What I do have is a constant flow of strong air flow up at the windshield even though I do NOT have the system set on defrost and this air flow blowing out of the windshield vents is definitely not warm at all even after driving around for a half hour or more.

Anyone have any ideas what I should be looking at next? I noticed the revival of the Jaguar PDU thread and got to wondering if there was any diagnostics in the car for the climate control system.
My suspicions are that I somehow do not have the various doors in the climate control system operating as they should when I set the controls for heat.

Any and all suggestions would be most welcome at this point.
--
Steve

 

ARE BOTH ROTARY VENTS OPERATING?
The actuator motors get STUCK and need a good 'smack' when they are placed in the same position for months (like all Summer or all Winter).

I kept a long wood dowel in my toolbox to tap the plastic actuator housings when they got stuck.

They do fail so keep one handy for a damaged unit (the upper and lower are both the same).

There are different ones for different Model Years. The harness connectors are the difference.

 

Where do you tap with this dowel rod? Where are these actuator housings located at?

 

If the hot water valve at the back of the cylinder head gets stuck or partially closed then you wont get much if any heat.

This unit fails quite a bit, (mine did) and unfortunately spares for the 94MY are unobtainable, anywhere. If you are faced with a failing valve, you'll have to go aftermarket and do some mods to the fittings.. .

Mine leaked as well as being stuck.. You can read the saga/solution here if you like

https://www.jaguarforums.com/forum/x...2/#post2054032

It may be your blend door actuators stuck on cold ike Bob said - in my case it was the valve ...it had been weak for a long time - I got mini heat flow but with the aftermarket (plastic, el-cheapo) valve, nice and toasty in winter and icy in summer.

Larry.

 

So how do I get to the blend doors to see if they are stuck?
Bob said something about using dowel rods.
Where do I stick these dowel rods?

 

One of the problems my 94 had when I got it was that a flap for the defrost setting had broken off and fallen into the heater box blocking the top rotor and causing the heat to only come out of the rear seat vent. I could shine a flashlight into the front center vents and see the offending piece laying there. It was a very intensive repair to remove it and effect the repair on the flap pivot but it seems to work fine now..... maybe this happened to you?

 

I pulled the glove box out of the car so I could access the blend flap motors. I was able to detach both of them and then stick a flat bladed screw driver into the holes to manually try to move the doors by rotating the screw driver.

The lower blend flap seems to mover quite freely and smoothly through about 180 degrees of movement. The upper blend flap door however only moves about 10 - 15 degrees. It does move since when I rotate it sharply with the screw driver in a counterclockwise rotation I can hear it clank against something.

What do the two doors do? I.E. by moving the lower one versus the upper one, what am I doing? If the upper door is somehow restricted from it’s full movement, could that be my no heat problem?

This car has been in a few accidents, one of which prior to my ownership in 2007 was bad enough to set off the airbags (thus why it has a passenger’s glove box instead of an air bag which would normally be there in a MY94 car). Is it possible that something has come loose down inside the heater box and thus restricting the movement of the upper door?


Upper blend door actuator


Lower blend door motor still in place

 

There is a 4 or 5 page description of this system which I have downloaded. I believe that I found it in the tech section up in the stickies in this (xj40) section. This is my way of saying "I don't remember which rotor does what." The flap I dealt with was for the left side of the windshield defrost setting. The rotor should move more than 10-15 degrees though. Maybe try running the car and see if you are getting heat out the rear seat vent.....

 

Looking in my documents its called Delanair IV. The diagram labels them both as blend flaps.it looks like they serve upper and lower respectively.

Here you can see the defrost flap where it had fallen into the heater box. I took this pic through the center vent hole

The loop end of the flap had broken off, but JBWeld ran to the rescue and all is well.

 

Jerry:
Can you provide any explanation of the steps you used to get the center vent opened up enough to take that photo?
I would like to be able to at least duplicate that so I can see if whatever is blocking my upper flap from moving is indeed visable.

 

When I did this, I was grasping at straws so I ended up removing way too many pieces. In any case, the center wood trim is press fit. Just carefully pry it outward. Then, as I recall the vents were just held in by the wood trim and can pop out. If not then it was just a couple of philips screws. As you can see in one pic, I had one of those cameras-on-a-cable at the ready but didn't need it. For the defrost vent, pry up on the center sensor fixture, its press fit too. I broke the pins on mine- its delicate also. Unhook the connector for the wires to the sensor to get it out of the way. Then the defrost vent is in by 3 phillips screws for which I had to use an extra short screwdriver. There is very little room there (maybe just use a phillips bit and a crescent wrench). Once you get the defrost vent out, you can push the flapper up through That hole. I took the actuator for it out too because the broken off pin/ hook part was in it. Its been a while and I've done several other projects since... I removed the Instrument panel and the passenger airbag also. I think that I did NOT need to remove the airbag, but the instrument panel obscured the actuator for the defrost flap. The instrument panel is pretty easy- 2 bolts at each side of it. One of the inboard side bolts also holds a support bracket for the center console. That one is a bit fiddly but can be done with patience. There are several electric connectors, but they're color coded and funny shaped so you cant really confuse them (while I had it out I changed a couple of burned out bulbs too). And as the Haynes Book Of Lies says- Installation is reverse of removal.

I removed the instrument panel to get at the actuator for the flap. You may not need to.

Through the windshield down the defrost vent. My tiny screwdriver is visible in the light reflection.

This is the flap after repair. In the previous posts' pics you can see the "plumbers tape" I used as reinforcement for the JBweld.

 

Thanks Jerry. I will give it a try this week or perhaps weekend.
This no heat "adventure" has been such a long road.
I don't think the car has ever had a working heating system since I bought it in 2007
I am determined to have some heat in the car for this winter.

 

Steve,

I just did a quick scan of this thread and I don't see a report that you've changed the thermostat. A stuck-open thermostat can significantly reduce heat in the passenger cabin. It will also lead to increased fuel consumption because the ECM will continue to apply cold-start fuel enrichment even after the engine has reached its highest temperature (but not proper full operating temperature). Just another potential problem to rule out in your pursuit of heat.

Cheers,

Don

 

Wow ... 12 winters with no heat! What a guy!

One was enough for me - priority *one* on the first spring days following that first chilly winter

Larry

 

In the "balmy" Midwest no less! BRRRRRRR!!!!!!

 

Well I originally bought the car when I lived in Phoenix Arizona.
I only discovered the no heat problem one year when we took the family to Grand Canyon on thanksgiving weekend.
We almost froze on the drive from Grand Canyon back to Flagstaff at night.

 

This evening I pulled the center vent assembly out of the front of the dash and then tried to peer down into the heater box using the access through this center vent.
I can see that there is indeed some stuff dropped down into the heater box blocking some of the flaps and blend doors.
What I still do not understand is what steps I have to go through to access the inside of the heater box so I can fix this.


See inside the heater box on right side


Same view on right side with a screwdriver holding the center vent flap open


Right side but showing the center behind the central flap

I think that these things I am seeing are shown in the one of the photos that Jerry uploaded earlier in this thread.
I have added an arrow pointing to the flap in Jerry's photo that looks like the things I am seeing dropped down in my heater box.


Jerry's photo with an arrow

 

Steve,

The easiest, and possibly only way to access the depths of the climate control module is to remove the dash. It's not nearly as difficult as it sounds. I think the Haynes manual may give all the steps. If you don't have the Haynes, you can download a mostly-complete U.K. edition here:

Haynes Jaguar XJ40 Repair Manual

Here are some photos of our '93 with the dash removed so I could repair the defroster flaps. On ours, the plastic hinge pins at the inner ends of the flaps had snapped off. They are under considerable stress from the vacuum solenoid. The broken pins were still in the hinges, so I drilled holes through each pin and into the end of the flaps and installed small stainless steel screws to hold them together permanently. I may have used some epoxy as well but I don't think it is necessary:





Cheers,

Don

 

All I did was remove the defrost grille on top of the dash. I was then able to push the broken flapper up out that hole. I did remove the instrument panel to get at the dash pot but that's not as awful as it could be. To get the 3 screws out of that top grille I needed to use an extremely short screwdriver. Now that I think about it, I believe I have seen them at Horrid Fright for about $2 a pair but I got mine at a Swap Meet. Don't over think it. I still think I took too many parts out......

 

I cannot actually reach the broken pieces that are down in the heaterbox because the center vent flaps that I am showing being held up with a screwdriver handle in the one photo block access.