2005 XKR Coupe

Did a long trip the other day and for the first hour and a half I could only get cold air. It eventually started working ok for the rest of the trip. The next day I could only get cold air again. Did a panel test and got no faults. I do not have a OBD reader.
On the return trip today I got cold air for 10 minutes then it worked again. The engine was already up to temp before I set off having had a drive with cold air again. After a refuelling stop I got cold air for about 5 minutes then ok again. Outside air temp was around 50F.
So now I don't trust the air system.
If it happens again I will take it to the dealers but just wondered if anyone here had had this problem or an idea as to the likely cause?
I imagine it is something to do with one of the sensors detecting the cabin temp?
Thanks in advance if any ideas.

 

In my car, as the weather gets cool in Chicago, I have a problem with cold air coming off the dash. Not just a little but it is to the point to where I have to wear a glove on my left hand. It is not coming from the A/C vent but off the defroster vent by the dash. It is outside air. It stops when I turn off the climate control. After a few minutes it seems OK. I think it might be caused by leaving a warm garage, and driving outside to a cold environment. It also seem to stop when the weather gets really cold, below 35 (US). Also seems to be worse at night. Hope this helps

 

Thanks Glenn. That is a different problem from mine.
Had a chat with the dealers and they want an hour and a half labour to diagnose the fault. They think it is the aux air valve, whatever that is. I just wonder if it's an air lock in the system.
Any way may just open the piggy bank and let them have a look. But I trust the dealers less than I trust my heater !
Steve

 

I have the exact same problem and am in Chicago as well. I have started to keep the climate control set to Floor only and that seems to help. All-in-all it is a pretty weak heater.

 

There are a couple of things to keep in mind. Sometimes when in Auto mode the AC will run to dry the air and help deter fogging on the windshield. It runs for a while, then shuts off.

My 2000 XK8 has a two stage heating system - apart from the main mechanical water pump there is a supplemental electric pump which moves the hot anitfreeze into the heater core. This system is on the firewall under the vanity panel on the drivers side. It includes a set of small hoses which, in my case, had kinked and restricted flow - worth checking. It is possible that you have some sort of temporary fault to the electric pump, though this is unusual.

 

Spurlee thank you.
I have found a kinked hose on the firewall on the left side in the engine compartment, hopefully this is the cause.
Also the header tank level appears to be low. The handbook says to fill to the top of the filler neck but that would mean fill the tank completely ?? Is that right ?

 

Well the kinked hose is supposed to be kinked, so it wasn't that.
Basically I'm only getting heat at higher rpm.
I'm suspecting the heater pump.
Can any one tell me the location of this pump in a 2005 XKR Coupe ?
I can't see it.mm

 

On my US spec. car it is under the drivers side engine compartment vanity panel hard on the fire wall. There are 2 hoses coming out from the firewall into it and another set from the engine side. There is an electrical connector on the assembly as well. I don't know which side it might be on for your car, I'd start on your driver's side I guess. Someone might chime in with a JTIS diagram.

Good luck!

 

Thanks, what you describe is the heater valve. There are 4 pipes from the valve and 2 from the pump. The lower pipe from the valve on the left side goes to the pump. I have now managed to have a good look with the aid of a diagram and the heater pump appears to be above the gearbox, not easily seen. Not at all easily accessible.
Looks too hard for me to do so it's piggy bank time.
Thank you for your input.

 

Before you break open the piggybank check the heater pump relay in the engine comparment fusebox. It is the lower rightmost relay. Swap it with the adjacent (lower center) foglight relay and see if the heat starts working and the foglights start failing.

Also make sure fuse F15 (10A) in the same fusebox is not blown.

 

Thank you White xkr.
Unfortunately the fuse is ok and so is the relay.
I'm convinced now that it is the pump.
The dreaded dealers are going to take a look tomorrow. I shall report back.

 

This has been resolved.

Problem..... Heater temperature varied with engine rpm.
Solution......the heater pump had failed, part Number MJA6710AA