As some of you remember, I bought my 2006 XK8 a month ago with no working heat. It does not matter if the car is fully warmed up or what setting the heat is on (defrost, full blast, high temp, etc) the car always blows cold air. I suspected the auxiliary heat pump, so I purchased one in anticipation to replace it. I also thought it may be the heater core plugged, or possibly a heater hose that was kinked and needed replaced.

Today I finally had time to tinker on it. I pulled the hoses off the inlet and outlet to the heater core on the engine side of the fire wall. I had to cut the hoses off after wasting too much time trying to pry them off. The one on the outlet side of the heater core (with the one way valve) was kinked bad. Inside the heater core hard lines I found there was gelling and hard deposits from the orange coolant. I took a garden hose and back flushed the heater core and it readily blew out the other pipe. I forced water through both the inlet and outlet pipe and it came out both sides with seemingly no problem. I turned the ignition to "on" but did not start the engine. No coolant came out of the disconnected hose whether the heat was on full blast or off. I thought the aux heat pump would run with the ignition on, blowing coolant out of the hose, but it did not...? I started the car and coolant began pumping out of the disconnected hose. I did not wait long and turned the car off. It wasn't spraying out, but just began to pump out before I turned it off in order to not have a coolant mess in the driveway. I do not know the car's system well enough to know if the pumping action with the engine on was caused by the auxiliary pump or the main water pump.

I also checked the one way inline valve and it worked as it should.

I ran a non kinked line and reconnected everything again, but without the spring clamps. I started the car and coolant began to dribble out the outlet side of the heater core (the hose was connected but no clamp, so had a little space to run out) indicating it was indeed running through the core, though I do not know how fast. I am assuming there is not too big of an air bubble inside there either, as it had a steady stream of coolant running out until I clamped it. I fully warmed up the car and it still blows very cold air with the heat set to high and the fans full blast.

Does this still indicate a blown auxiliary pump? Should it turn on with the heat set to full blast but with the ignition on and the engine off? Will coolant readily run out the heater core if the auxilliary pump is dead? I don't want to get into the mess of replacing it if the signs aren't pointing to it. There is a possibility that there is an air pocket in the system, as I did not burp it. But it is showing the same signs as before I replaced the kinked hose and blew out the heater core. Or is this possibly an electronic switch inside the heater controls inside the car not telling it to turn the heat on inside?

Any help very much appreciated.

 

You can do a number of sanity checks. First, check the fuse to the pump. If the fuse is OK, then locate the pump and try to figure out if it is actually running. Try and disconnect it from the harness and check if you hear/feel a difference. Check the power on the harness side as well. Also, depending on reach, get a cheap mechanics stethoscope to help you figure out if it is actually running.

FWIW, it seems these pumps wear out from use (the posts I have seen show a repair with new brushes), so I am a bit surprised to hear of a failed pump on an '06. On the other hand, everything ages a day every day...

 

Does it start to warm up a bit if you rev the engine? My pump was seized when I bought the car but I could get some heat when the engine got above 2k revs. If it doesn't, I would suspect something other than the pump, heater matrix, blocked hose, etc.,

 

Just an update with a good ending. I had purchased a replacement Bosch auxilliary heat pump and then the weather warmed up...well you know how that goes. Since I didn't need the heater the project went on the back burner.

Just the other day in the rather cold weather while driving, I kicked the heater on and viola, the heater blew hot air. I must not have ran the car long enough for it to fully warm up when I tested it earlier this year after replacing the pinched hose. The sad thing is, I have driven it the last few weeks in the cold with no heat because I thought it was broken! It's also sad to think I froze my butt of in January on a 10+ hour car trip all because of a little pinch!

So if your heat stops, it may be something simple like a pinched hose instead of a blocked core or a heat pump.

Just goes to show you it's a good idea to trouble shoot these cars before you throw money at them. It seems like most of the fixes I have performed on this car have really been extremely minor fixes costing a few dollars and some time.

Here's a picture of what the pinched hose looks like while on the car (right side of the pic):

 

Glad you found heat at last and that this was a simple fix! Good to know.

Granville