Mechanics

CLIMATE CONTROL HEATER NOT WORKING

2003 Jaguar XK8 • 80,000 miles


Vehicle recently moved FROM Arizona TO Tennessee. Obviously in Arizona, I did not require the heater function so I never suspected there might be a problem. Here in Tennessee, it is starting to get cold so I discovered the problem.

Air Conditioning works great. Control panel test does not show any stored faults and the actuator check procedure appears to perform properly. Vents open/close properly, fan speeds operate etc. When set to heat, the center vent closes and I feel air at the foot well and side vents though it is cold air. Additionally, when I set system to defrost, the fan speed does indeed go to high speed but the output air remains cold.

Coolant level is proper and the vehicle does not over heat. After vehicle is up to normal temps, I feel the radiator hoses and both upper and lower hoses are hot. I have NOT attempted to clean the cabin air sensor on the panel beneath the steering wheel. I will probably try to clean that this week end.

How should I test the electrical heater control water valve? Also, if I recall, the vehicle uses an auxiliary coolant pump to pump heated coolant into the heater coil. I have UNsuccessfully attempted to trace the hose from the heater control valve to the pump. Where is that auxiliary pump located and how should I test it for proper operation?

Thanks in advance for any information you might be able to share with me to resolve this problem.

Jim
Avatar
DOCJIMCA
November 6, 2011.



See if hoses are hot on both sides of valve. If not pull plug as it is default on (block) no juice off (open) thoughtful at least.

Tiny
Fixitmr
Nov 6, 2011.
Hi fixitmr: Thanks for the suggestion. Two items: 1) I cleaned the cabin temp sensor yesterday and both the sensor and the small, rubber connector piper were very dirty. 2) Today, when I got engine up to temperature, I felt upper and lower hoses on both sides of the valve. Both hoses on the drive side of the valve were hotter than the hoses on the passenger side of the valve. I pulled the electrical connector and drove the car around the block and felt the hoses again. Upper and lower hoses on both sides of valve were pretty much the same temperature (hot to the touch). However, the cabin air was still blowing cold.

Does that imply the water valve is working properly and does it point us closer to the auxiliary coolant pump? If pointing to the pump, where is that located? Would you have any sort of picture showing its placement and suggestions on getting to it?

Thanks once again for your input.

Jim

Tiny
DOCJIMCA
Nov 6, 2011.
See if you can locate in and out hoses to heater core and feel the temps.

Tiny
Fixitmr
Nov 7, 2011.
Also would point out that the orange coolant used is prone to sludging in the pump and the heater core creating slow restricted/blocked flow. You might locate pump by tracing hoses from valve.

Tiny
Fixitmr
Nov 7, 2011.
The pump itself is a magnetic impeller drive design. This means if it's clogged it will still run, just not pump or or pump slowly.

Tiny
Fixitmr
Nov 7, 2011.
Thanks again for your input.

Following your most recent input, I felt hoses at the firewall going toward heater core and I again felt hoses at water valve.

Observations at firewall: Passenger side hose hotter than driver side hose though both pretty warm

Observations at water valve: BOTH top hoses were much cooler than both lower hoses on both sides of valve. Lower hoses both pretty hot to the touch on both sides of valve. I would have thought both top and bottom hoses would be close to each other temp wise.

The above observations were made AFTER cleaning the cabin temp sensor and aspirator hose.

Your comment regarding orange coolant was something I had NOT considered. Is there any way to remove two hoses and force either air or maybe water through system and flush it out without damage to the system? OR perhaps remove the water valve and hopefully locating the pump in the process and remove them from vehicle and clean them?

Sorry this is taking so much time but if we can't resolve the problem I will have to take it to the dealer and pay their outlandish fees.

Thanks once again,

Jim

Tiny
DOCJIMCA
Nov 7, 2011.
You can try a core flush with water to see if flow is good.

Tiny
Fixitmr
Nov 9, 2011.
Thanks for the suggestion.

Yesterday, I called a local shop and scheduled a flush to include the heater core as well as running a diagnostic on the AC/Heat system.

Thanks again,

Jim

Tiny
DOCJIMCA
Nov 9, 2011.
Let me know what they find. The system also has check valves in the hoses that could leak/malfunction.

Tiny
Fixitmr
Nov 10, 2011.
Will do and thanks again.

Jim

Tiny
DOCJIMCA
Nov 10, 2011.
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