Hey everybody,
Just recently my 1995 Jaguar XJ6 Vanden Plas starting experiencing this problem. I'll have the temp set to be pumping out warm/hot air but nothing but cold air comes out. The temperature of the car is where it's supposed to be.

It's getting colder up here in Canada, so any help would be greatly appreciated!

Any ideas? It's calling for heat but nothing is coming :|.

Thank you

 

Sounds like the climate control unit or a plugged heater core

 

Does anybody think it could be the Heater Valve?

 

well, it could but usually its a plugged core, or, more likely, bad brushes in the recirculation pump motor. If you choose to go after the valve, remember it powers ON to close.

 

I hit the heater valve with a rubber mallet and now the heat works just fine! Let's hope it stays like that for winter.

 

ROFL, my late father always said that what you paid for was knowing where to hit it. He was a TV repairman.

 

I have the same issue, heat used to work, now it doesnt. Where is the heater valve so I can hit it!

 

I have the same problem with my '98 XJ8. I have run through all possible avenues thus far, short of removing the heater core. My thought is that the heater core is plugged. I got a wild hair today to check the voltage coming to the valve. There is a steady stream of 6.5 volts to the valve. Is that correct, or should it be 12 volts? Further, I am getting 6.5 volts whether the car is on or off as well as if the heater is on or off.

My understanding is that it is "energised" for closed" and "not energised" for open. My dilema is why I have power at all times??? Is this a relay issue? If so, which relay is it. I referred to my JTIS for about 2 hours trying to locate a solution but I didn't find anything.

Any takers for this one?

 

I am a Jaguar rookie, but when I have had this issue in other cars it has been the result of a bad thermostat. Any chance that could be the problem?

 

touche'
that one hadn't come to mind yet, but is quite possible.
also could be blend door failure.

try a cooling system flush and see if that doesn't help any?

but you are correct in your understanding that for the valve to be open, it is not energized. that's an interesting one.

 

Winter's coming...good time to get this near the top again.

My heater didn't work when I bought the car a few months back. I fixed it today after checking everything since I didn't know what was wrong:

- Heater core? I back flushed it to find out it passes water with the best of 'em. Disconnect the hoses going to the heater core; one at the electric water pump, one at the water valve and put your garden hose on the one from the water valve. If there's no or too little flow, it's clogged. Mine wasn't.

- Electric water pump? It runs with 12V applied...so I applied it straight from a jumper pack! Runs great.

- Water Valve? This is what I spent the most time on. Completely removed it and saw that the solenoid actuates when I apply 12 volts, so I know it wasn't stuck. But was it doing what it's supposed to...especially with that pesky 6.5 (or so...mine was 6.2) volts there whenever the ignition is on? Well, I just plugged it in and watched; no movement with the 6.2 quiescent voltage. That told me the 6.2V is normal. Put the water valve back in convinced it must be air lock...

- Air Lock? That did it. There's got to be a better way of doing this and I've got an idea or two; but here's what I did today...Kept the top, rear hose off the water valve; the other 3 I secured in place. I loosened the reservoir cap (where I would add coolant), then I gently twisted the loose hose at the water valve up to where I could pour water into it while keeping the opening slightly above the highest hose. Once water started coming out of the open water valve connection, I knew the heater core and hoses were filled. I then covered the open connection with my finger and continued pouring water in. It took a few tries to find just the right contorsion! Once the hose was full I slipped it on, tightened it and followed the radiator refill proceedure for purging the system. The heater is now a real heater. :-)
Yes, there's got to be an easier way!

 

Sorry...I forgot to mention that the majority of the info I used to fix my heater came from various posters here.

Thanks to all!

 

Good work!

Air pockets have traditionally been a V12 problem but, in thinking about it, there's no reason the 4.0 couldn't have the same problem, considering the layout of the system.

My own heater doesn't always work too well so now I have something to look for.

Cheers
DD

 

Thanks Doug.

Is there an easier way to get the air out? I've read about the difficulties some have had even going to the extreme of sharply jacking the front end up to get the air to flow out.

I'd love to know an easier way! I have a couple of ideas and will have to get a couple of pics to get input on the feasability of them, but maybe somebody already has a known method.....?

 

Hitting the valve is not a permanent repair !! I suggest you fit a new valve and also a new heater circulation pump.

 

Here I am once more approaching winter in a Jag with no heat!

This is the information I've been able to gather from my car.

Low radiator fluid light appears to be on (Light right above SRS AIR BAG) on the right side.
Aircon works perfectly!
Antifreeze is full to the top of the Full line.
Heater blows cold air.

I've looked through this and every-other thread I could find and theres something about a pump/switch and I cannot seem to find it! If anyone has an explanation of where this would be on a 96VDP it'd be very helpful .


Thanks a bunch!

 

fantasic.-
I do noit know where you are looking, but the pump and valve are between the brake booster and the fender, just in front of the firewall. You will notice a bunch of strange plumbed hoses about 7/8 " in diameter connecting it all to gether. It feeds the matrix, which is, of course, inside the car, on the other side of the firewall.

 

Hi fantastic and welcome to the forums! I have not been on here very long myself but am learning that there is a ton of info throughout the forums and lots of folks always willing to give direction where needed!

I have a '97 VDP and recently got my heater working as I posted above a few weeks ago. Since a picture is worth a thousand words...

The first one is for perspective:
The heater valve and electric water pump will be found just behind and below the heater hose you see right next to the brake fluid reservoir and running back toward the firewall.

The second one shows the top of the water valve just in front of two connectors. One connector goes to the water valve with the other going to the electric water pump. Additionally, the water pump has two hoses; one going to the water valve and the other going into the firewall to the heater core.

I hope you are able to get the heat flowing soon!

 

So as I was changing the octopus of hoses around my water valve, I pulled the valve and saw some shrapnel inside. One of my check valves had broken and pieces apparently made their way into the water valve. When I disassembled the valve I noticed it only had about 1/8" to 3/16" of travel in the shuttle. I thought this was a bit short but that is only speculation on my part. Does anyone else know what the stroke length is of this valve? The valve does close on the seat, I checked that. It just seems to have a very short stroke.

I realize most would just change the valve but at $400 to $550 depending on who you talk to I'm game for working on it a bit first. Any takers?

Thanks,
Mike

 

While I had mine removed, I did plug the connector in for the sole purposee of observing the travel of the plunger...it wasn't much and though I didn't do any kind of measuring, the 1/8" to 3/16" you saw is about the same as what I saw. Mine's working great after the reinstall.

I'm with you...why spend $$$$$$$? If it was put together, it can be taken apart. If it's broke, it can be fixed. Wellll.....usually anyway!