For the last couple of years my 97 XK8 hasn't been able to blow warm air, I haven't used it in the winter so it hasn't bothered me too much, however I want to fix it now!

If you look at the heater mixer valve on the bulkhead behind the engine there are four pipe connections, two on each side. Above and to the right are the two hose connections through the bulkhead to the matrix in the cabin.

With the engine up to temperature and the climate control set to blow as hot as possible the only warm hose on the mixer is the top left one, all others are stone cold, both hoses through the bulkhead are also cold. If I disconnect the electrical connection to the mixer there is no change to the cold hoses.

I understand that there is a pump in the sytem too, however even if this has stopped working I'd still expect some flow and gradual warm up of the hoses. Any ideas? How can I check the mixer (I know that Jag don't call it by this name)? Where is the pump located?

Could anyone tell me what each of the hose connections are for on the mixer, i.e. hot supply engine, outlet to matrix etc...

Thanks

 

Hey Alastair - found your post when I was looking for help on changing a heater matrix - did you get anywhere with your problem?

Thanks

Peter

 

Unless you know what your doing, the heater matrix is a pain in the you no what to do, and even if you do know what your doing, it's still a pain, don't do it unless you are a 100% sure thats the problem. I would try back flushing the heater core. The heater pump is on the left side of the car, right next to the engine, before the expansion tank. Also you check the heater valve itself. The heater valve is on the left side of the fire wall, behind the tank. Back flushing has work for me with these cars, so that's what I would do first.

 

Thanks for the advice. The heater valve and pump have already been replaced, as has a one way valve in the system that was gunked up with what looked like emulsified grease (wherever that came from). Is there a link to the back flushing process anywhere on this forum? Just trying to avoid a large bill for a relatively inexpensive part.