Hello everyone i am hoping that someone on here can help me finding out why i cant get any hot air in the car the heater blows cold but cranked up the heater to high no heat just cold dont know where to start im guessing thermostat would be the first place any help and advice would be fantastic Thanks in advance

 

I would start at the heater valve?

It is between the engine and firewall, maybe closer to the drivers side of the car. Its a cheap brass looking thing.

I have found that replacements often leak right out of the box, so check yours before installing. Or you can replace with a plastic one, that seems to work well. I'll dig up the part number later.

 

The cabin heat hot coolant circuit has an electric pump on the cars left

You can tap on it with a broom handle to loosen up the electric motor brushes inside motor , gives a little more life

A DIY brush replacement # 33A or A33 times 2 brushes

 

 

With the heat turned on the pump will run at all times

A coolant solenoid valve will modulate open - closed and fuses involved

brushes pic and source coming

There are sources in England

.15" x .15" x .35" BRUSH 33A

 

The thermostat does have a whole effect on both engine block and cabin heat hot coolant circuit flows

Highway gas mileage low on the dash indication ? not allowed to go into closed loop engine efficient regulation by way of not hot enough coolant fluid ( as a whole ) temp

But the cabin heater electric pump pulls just heated coolant from one of the cylinder jackets for faster cabin heat , you will see a medium size hose coming off left rear top of engine block

If you run the engine at high RPMs ( warm engine not on driveway , overheats transmission per TSB ( ? ) ) there will be a little hot coolant flowing through the heater circuit which will prove the heater coolant solenoid is opening

This high engine RPM reported by others cabin heat hot coolant flow is a quirk corrected by a check valve on the same system later V8 X308

See page X of post # 4

Repair Manual - Jaguar Forums - Jaguar Enthusiasts Forum

 

G'day Steve,

For hot coolant to flow through the heater matrix the pump needs to run and the heater valve needs to be open. You can feel the pump to see if it is running, if it isn't then that is your problem.

If the pump is running the heater valve must be shut, it is failsafe open so if you can find the power connector for it unplug it and the valve should open, you may need to apply a technical tap to the valve to jar it open.

If you determine that the pump is running and the valve is opening then then the actual heater matrix may be blocked with scale and years of silt build up. You may be able to clear it by disconnecting the hoses from the heater matrix and flushing it through with a garden hose. If you get little or no flow with a garden hose then the matrix is definitely clogged and needs replacing. I see your car is RHD so the heater matrix can be accessed by removing the glove box and surrounding trim. It is a fiddly job to R&R but if you are handy with the tools it is pretty straight forward.

I had a blocked matrix in my car years ago and I removed it and flushed it repeatedly with kettle cleaner over several days and it eventually came good.

Cheers and good luck,

Jeff.

 

Concern about too much garden hose water pressure for a about to leak heater matrix ( ? )

Someone does have good pics of the heater core / matrix fittings from the cabin side as top side engine compartment can be a challenge

If I recall seeing the pic the disconnect hoses come out on the cars left cabin side at the heater core / matrix

Maybe a bottle of radiator flush solution ( diluted ) from above and a milk jug / hose setup , let solution soak

I found one of my heater hoses pinched / folded closed by previous owner

 

Thank you everyone for your replies i will have a check on the pump first as that seems to be the easiest thing to start with and then go from there what a complicated set up the jag seems to have but it is a jag i guess but once again Thank you for all this advice i will reply to this thread to inform you all of the problem SHOULD i find it