Hi all, I have done a search already of the problem but did not come up with an answer.
My 01 VDP does not produce heat for the cabin starting when cool weather arrived. I changed out the thermostat, was only a year old, for a new factory stat (Motorcraft package, Waxstat inside) but still no heat. I noticed some posts saying the aux water pump is the usual culprit but when I touch mine it seems to be running. Unplugged it does not run.
is there a way to test the water valve under the exp tank or do I just replace it? They are pricey….
Thank you…

 

Unplug the water control valve electric connector. This should give as maximum heat as possible if nothing is clogged.

 

Most likely the heater core is calcified shut due to lack of usage.

 

TSB 303-11 for you.

 

My car after last two winter in a first drives has done this same. Not from the beginning of the drive. But suddenly. Slowing down to the stoplight and suddenly no heat. It was not nice when outside temp was -6*c(21*F). Both times all I had to do is from the stoplight raise the rpm slowly with 2nd gear selected up to the 4-5k rpm. And keep them there like few seconds. Suddenly hot air rushed from the air vents. After that water valve works whole drive season without any issue what so ever. Water system is pretty much spotless what I've looked in to the sc cooling system pipes and inside of the aux water pump.

In topics car It easily can be clogged core.

 

The electric heater pump design is such that it does not have a mechanical connection between the impeller and the motor. The motor drives the impeller via a magnetic field which, if the pump impeller is clogged or seized for some reason, will allow the motor to still run. So, the motor running does not mean that the pump is pumping. Before you go deeper, you should take the pump out and bench test it. If the pump impeller is not turning, you may be able to free it.

 

I guess that magnetic impeller is there too because how water control valve works. Valve blocks the water flow completely time to time. That is the way it controls the water amount in circulation in the core. Less block on time means more heat and more block on time means less heat. I guess that normal impeller type pump may cavitate during this valve on /off/on/off cycle wen regulating heat? If so how fast it makes issues is not known.

 

Might be an obvious and dumb answer but did you turn the temperature all the way up? I mean until it will not go any higher? Also, sometimes I don't get much heat from the top vents unless I select top vent output only. Then after that it works fine.
I sort of had that similar experience a few years ago with Jag 3; disconnected the hoses and did not see anything wrong. Put a meter on the wires to the heater motor and tried a number of settings and when I put the hoses and connectors back, everything worked again. No idea what was wrong but it just started to work again and has never been a problem since. I hope your car starts again!

 

I remember a similar "no heat" situation when it turned out to be the vents were clogged with
decayed Styrofoam. I suspect you may have already looked into that possibility.

 

Thanks for all of the replies, but I am still chasing the problem. I have disconnected the heater valve wire so it will go to default mode and “maybe” get a tiny bit of heat. Today I went to the next step and removed the coolant pump, found nothing amiss. However I have no power on the plug to the pump. The number 1 relay in the engine fuse box is for the coolant pump. Swapped relays about but no change. My new question: is there a fuse in addition to the relay, and where might it be?
Many thanks…..

 

This is a handy thread...
https://www.jaguarforums.com/forum/x...r-woes-208746/

 

It is one of the fuses in the engine fuse box, cannot remember which one.

 

Thanks all, I have just located the fuse, #15 in the under hood box. It was good, still no power to the pump.

 

Most likely the heater core is calcified shut due to lack of usage.

 

Lack of usage shouldn’t be a really big issue here this week…

 

When you’re diagnosing power to the pump, make sure the engine has ran for at least 3 minutes from a cold start. It’s been awhile since I’ve looked at one for the same situation. However, if memory serves me correct, I believe there’s some logic from the climate control that doesn’t run the pump unless there’s a bit of heat in the cooling system. I also think there’s a way to get codes from the CC that doesn’t require a scan tool. If I’m wrong, feel free to chime in. I’d still bypass the pump with a barb fitting to see if there’s any change.

 

Yes it is possible to read cc codes from the cc panel.

1. Press ‘Auto’ and ‘Recirc’ and then turn ignition on - this puts
   module into diagnostic mode.
2. Press ‘Auto’ to start display of codes.
3. Press ‘Demist’ to cycle through codes.
4. Press ‘Demist’ and ‘Heated Rear Demist’ to clear displayed code.
5. Press ‘Recirc’ to exit diagnostic mode.

My car was equipped hand drawed flyer type manual how to read codes and to do something else too(can not remember what). It is possible to do very basic function tests too while in diagnostic mode.

JagRepair Fault code pdf

 

..thanks Vauxi, very simple way to diagnose.

 

Warm the engine up

tap with a broom handle end the electric heater pump , but not too hard as old rubber mount points

this jars loose the electric motor heater pump brushes ( 2 ) that give it a little more lifetime that probably need replacing

The heater pump should run at all times with the coolant flow regulated ( solenoid that can be tapped ) to maintain selected cabin temp

this will not be shown as a code on the front panel bite test

There is a specific heater pump fuse # 15 / 10 amp engine:" compartment " fuse box and # 3 / 10 amp engine " compartment " fuse box and heater pump relay that can be tapped

See page 37

X300 01/E COVER (jagrepair.com)

The X300 and X308 are the same manufacture ( Denso for the climate control ) and almost exactly alike

Later model X308s ( 2001 or so ) use a Bosch heater pump motor which is a replacement option converting the electrical connector

See item # 4 , it is not named correctly

Genuine Water Valve, Pump And Hoses-petrol For Jaguar Xj 1998 - 2003 (from 812317 To F59525) Classic | Jaguar Land Rover Classic Parts

and

.15" x .15" x .35" BRUSH 33A (eurtonelectric.com)

You may find the 2 brushes needed faster at a hobby or hardware store

They can be filed down to size

The cabin temp sensor clogs with lent that can be cleaned with a brush ( no solvent spray) , does not show as a bite test code

This biases the cabin temp as higher than actually is cutting back the heat flow

See page 69 of the XJ section page 45 to 116

T703 BOOK (jagrepair.com)

 

Has anyone ever seen this Bosch pump? It would be great to have a picture and a Bosch part number.

Regards Ben