The heater on my 2000 XK8 seems not to be working. When I turn the A/C off and the temp up all the way, the temp coming out may be a little warmer than outside 70 degrees. When I have the A/C on to remove the humidity and turn the temp up it gets to the same temp as without A/C but no warmer.

When turned down the A/C gets ice cold!

Does anyone have any ideas what the cause and or what to do to fix?

Thank you

bcucharternet

 

I had the same problem. I solved it by back flushing the heater coil. Only took about an hour. Sears has a tool for removing the hose clamps and a hose removal pliers will make the job much easier. Good Luck.

 

The most common problem with loss of heat is the failure off the small pump motor located in the 'octopus' hose between the engine and firewall. If the motor fails, the impeller blocks the flow of hot coolant to the heater core.

Find and hold on to the small motor while someone calls for heat. If you can feel vibration like a motor/pump is running it is probably OK.

 

if the aux water pump isn't working you will only get gravity heat as the pump will not circulate hot water thru the heater core... evidence of this is usually a collapsed hose at the firewall going into the heater core . the pump is quite expensive and difficult to change as its mounted above the transmission .

 

How did you back flush your heater core?

 

I’m sorry for the delay. I was away on family business last week.
The 2 heater hoses are on the firewall behind the cooling system expansion tank. I loosen the tank for better access. I removed the heater hoses and I used a few pieces of ½” water hose. A hose clamp removal tool and a pair of hose removal pliers make this job much easier.

Sears.com

3 Piece Long Reach Hose Grip Pliers

I then slid the water hose over the nipples and clamped lightly if needed. One hose hooked to the water spigot, the other side was the drain. I turned the water on slowly until it ran freely and used a bit more pressure, then reversed the water direction. I didn’t seem plugged up but after it was all done, the heated worked better than ever. Good luck.