New (to me) '94 3.2S - No heat from the heater.

[scratchnsniff]

Hi guys, just got myself a 1994 XJ40 3.2S auto and so far it's the mutt's nuts.
The only real issue so far is that there is no heat whatsoever coming from the heater. Not a huge problem at the moment, but it needs sorting.

I've read through this forum and other online sources and I'll give you some detail in the hope the source of the problem is clear.

Firstly, the car seems to warm up OK, the temp gauge in the dash reaches halfway after a minute or two and the radiator top hose gets hot quickly too. Watched with the coolant cap off the reservoir in case there were any bubbles indicating an air lock as it warmed up but none appeared.

The blower seem to operate OK too, turn up the dial and after a couple of seconds the fan responds. (I gather a delay of a second or two is normal)

When I switch it to Demist I can hear flaps and motors moving about behind the dash, and the air comes out the windscreen vents with some force on both sides.

When I switch the Demist off I can feel lots of cold air at my feet.

But nothing I do seems to make the air warm. Tried turning the temperature dial back and forth and giving it a few minutes, the slider for the centre vents, switching it to Manual, Recirc, Demist etc, but nothing.

I found the heater valve under #6 inlet manifold pipe but apart from verifying there's a vacuum from the pipe when the temp dial is set to Cold and none discernible when it's set to Hot, and giving it a light tap with the wooden end of a small hammer I can't get near it, or even see it to try and find where the little actuating arm is to try and free it up. These must be an absolute pain to replace?

Apologies for nicking someone else's photo I found on this site, I tried taking one myself but the results were crap, but I did notice the hose that can be seen (that disappears behind the bulkhead, does it go to the heater?) here got warm , but the one below it is still cold, if that sheds any light on things.



Any suggestions as to what I can try next?

[Dave F111]

Hi

My guess is the valve has seized up. You may be lucky & unseize it but it's awkward to get at and you'll have to take it off anyway.

Dave

[donkeyotty]

My valve had siezed up and (luckily) I managed to free it off by sousing it with WD. Worth a try

[MagicDoormouse]

Not a nice job to do but not impossible. I'd go with Don's suggestion first of all and soak it in WD

[naki_k]

if you can get your hand to it, you can operate it manually, to try and unstick it
also, if the outlet pipe out fo the valve is not hot, then its not opening! simple

some pics here
viewtopic.php?f=18&t=7893&hilit=+heater+valve

[scratchnsniff]

if you can get your hand to it....

That seems to be the $64k question.
By looking at photos of the valve I can figure out that the little operating arm is underneath it, towards the bulkhead side, but how on earth do you get anywhere near it to get some oil or WD40 to it, is there a knack or does stuff have to come apart?

[naki_k]

If you remove the flexi rubber intake elbow, you might be able to get your hand to it from underneath, but I have never needed to try it yet.

[old del boy]

These water valves fail in the open position as shown here ,



this means you should almost always get hot water to the heater as it's more likely to seize through lack of use when the engine is not running , unless of course there is no vacuum to it which is rare , i think it is more likely that the bottom blend flap is stuck in the full cold position , this can often be coerced to work by a bit of a whack in the appropriate area shown in this diagram ,





Derek..

[Steve_D]

Also note that this valve is vacuum operated from the heater unit from a vacuum take-off originating on top of the inlet manifold. Check the connection (adjacent to pot 5 on my old 3.6) - thin black tube with elbow connection. My elbow connector was deteriorated and needed covering with heat-shrink to get a good vacuum. A fault/disconnection of this causes a lumpy idle.

[scratchnsniff]

Cheers for the info guys & the diagrams.
So am I right in thinking I can get at the bit that needs whacked by taking off the panel under the dash on the driver's or passenger's side, or both?

I'll give it a shot but like I said at the start, there's definitely a fair bit of movement going in in the depths of the dash when I set it to demist and there's no warm air coming from anywhere.

Also there's definitely a decent vacuum coming off the wee pipe that goes onto the heater valve, so I think that's OK.
Also as a point of interest, I'm surprised not all these cars have aircon. Can you tell from the control panel if mine does or not? There certainly seems to be air cooler than ambient temperature coming through the vents when I turn it to cold, but there's no signs of it on the controls anywhere although the handbook refers to 'Climate control'.