It is finally cold outside so I turned on the heat in my 2000 3.0 S-Type and I am having some problems.

When I set the thermostat to Hi and then cranked the fan to Max, the following is happening:
- No hot air on the two left dash vents, slightly warm air (but far from hot) on the two right vents.
- The warm air (on the two right vents) goes cold when at idle and then goes back to warm when accelerating or cruising around 20+ mph.
- BTW, my temperature gauge (when the engine is warm) is right in in the middle (vertical orientation) and does not change while driving. On an old Mazda, I had experienced heater problems while seeing large fluctuations on the temperature gauge.

Can anyone please help?

 

THAT REAL NICE DUAL ZONED HEATER CONTROL VALVE, MUCH EASIER TO CHANGE ON V6 RATHER THAN A V8, BUT TRY THIS FIRST. REMOVE THE HOSES THAT GO TO EACH SIDE (SMALLER 2) PUSH IN THE PLASTIC CLIPS AND PULL OFF, DONT LOOSE THE 2 ORINGS OR PLASTIC SPACER BETWEEN THEM. bLOW COMPRESSED AIR TO SEE IF CLOGGED USING A RUBBER TIPPED BLOW GUN. IF CLEAR REPLACE THE HEATER VALVE AS FROM LACKOF USE THEYRE PRONE TO SEIZING CLOSED INTERNALLY ALTHOUGH THEYRE A NORMALLY OPEN VALVE TILL ENERGIZED CLOSED

 

Brutal,

Thanks for the answer but could you please elaborate?

- What does the dual zone heater control valve look like?
- Where is it located and how best do I get to it?
- Do I just have to remove the climate control instrument panel below the radio?
- Is this in the JTIS? I just checked it and did a search on "heater control valve" and nothing came up. I found the "Dual Coolant Control Valve". Is this the same as the Dual Zone Heater Control Valve?

Per the JTIS:
Dual Coolant Flow Valve
Removal
1. Drain the cooling system.
2. Remove the air intake tube. F
3. Remove the receiver drier.
4. If equipped with 4.0L engine, remove the auxiliary coolant pump.
5. Disconnect the dual coolant flow valve electrical connector.
6. Disconnect the supply and return hoses.
7. Remove the dual coolant flow valve.

If this is the same as the Dual Heater Control Valve, are these instructions good? I have found that JTIS is not always the easiest solution.

 

yes except you dont remove the drier, you leave the hoses attached to the valve, but remove them from the connection on the other end. Then once you get it out pay attention to the position of each hose on the valve and install them on the new valve then snake it all back down there and hook it back up

 

I have an update:

I've been too busy to work on the Jag but I've been driving it a little. What I have noticed in the past few weeks is the that heat is working better. When the engine is warm and I'm cruising around 30 mph or more, I'm getting heat on both sides (although I'm getting more velocity out on the drivers side). If I adjust the temp on one side or the other, the Jag seems to make the proper adjustment. But, when I go to idle, I lose all the hot air.

Again, the engine temp is pegged right in the middle with no fluctuations.

So is it still the Dual Coolant Control Valve?

 

UNHOOK THE LINES OFF THE RUBBER PIPES AND WITH A RUBBER TIPPER AIR BLOW BLOW TO SEAL AGAINST THE PIPES, BLOW INTO EACH 1 TO UNCLOG, IF YOURE LUCKY THIS WILL FIX YOUR PROBLEM, AND THEN GO BUY A LOTTO TICKET, IF NOT YOU STILL NEED TO REPLACE THE VALVE