Hi guys, I have a 2001 Jaguar S type V6 3 liters and I have a problem with my cabin heater. I no longer have warm air on the left and right. I read on the internet that this car has a lot of problems with the cabin heater. Some change the DCCV valve, others the air conditioning control panel or the valve motors. I operated the valves with the air conditioning control, I hear the valves open or close. Under the hood, the cooling system pipes are hot and also the heating system pipes are hot. However, I noticed the cooling water is almost cold in the reservoir despite the water temperature gauge which is normal. I thought there was air in my circuit. I opened the fluid reservoir and let the engine run for 20 minutes. My water is lukewarm, I can touch it without burning myself. What I read online is that there are two valves, one on each side that opens or closes to let air through (hot or cold), yet I only get cold air. What's more, when I set the temperature from 22 to 20, the blower varies (more or less). From 22 and above, the valves facing the passengers close and the air blows through to the feet and the windshield. I ran my car through the diagnostics and I don't get any errors. I don't think the problem is with the control panel or the valves. But I don't understand why the pipes leading from the DCCV valve (the double valve located at the bottom of the cooling radiator) that go into the passenger compartment are very hot while the pipe that goes from the DCCV valve to the reservoir is cold. Can you help me please?

Thanks, Marc

 

Review this thread so you understand how the HVAC system works, and how to diagnose several issues:

https://www.jaguarforums.com/forum/s...ol-how-185002/

Karl put quite a bit of effort into creating this guide.

 

Hi guys. Thanks NBCat for the link. I ran tests according to the procedure. Cold engine, I turned the air conditioning on full blast. I waited 8-9 minutes to get the normal coolant temperature needle in the middle. I took the temperatures with a laser thermometer on the hoses going into the passenger compartment. On the left cabin top hose 27°. On the right cabin middle hose 22° on the lower return 30° On the radiator hose 63° 12 minutes after starting I have in the same order 25°/27°/37° radiator hose 70°. After 15 minutes 42°/46°/52° radiator hose 81°. Then I put the temperature to the max in the passenger compartment. Result 48°/42°/44° radiator hose 80°. After 20 minutes 50°/47°/45° radiator 80°. I measured the air temperature in the passenger compartment. Driver side 12° Passenger side 17°. When I went from coldest to hottest with the air conditioning control, I heard a valve in the dashboard. The air distribution is manual so there was no change (air to the feet, air to the windshield........) I think it is the valve of the hot / cold mixer. On my fuse under the engine hood I have 12 volts. So here is my conclusion. I do not have an electronic problem (air conditioning panel, temperature sensor in the passenger compartment or stuck valve). I think my valve is dead. Besides, the water that returns to my reservoir (DCCV pipe to the coolant reservoir) remains relatively cold 45°. I will therefore order a new DCCV valve to replace it and I will keep you informed. Thank you.

 

Good job and hopefully that new DCCV will fix everything. Now if you read Karl's fine guide and if the bad DCCV was left too long it will take out the RCCM board in the HVAC system. This can be seen on the PCB and can be repaired by you or it can be sent off for repair and updating.

The system was designed wrong from Ford. When the DCCV's start going bad the solenoids start drawing too much current. The PCB in the RCCM is not rated for that and you get burned out traces. The update is installing some fuses to protect the board as should have been done by Ford. The repair is simply bridging the burnt trace with solder.

When my DCCV went bad in my 2005 S-Type R I had let go for too long. After the DCCV was installed I still had problems and finally opened up the RCCM (Remote Climate Control Module) to check and found the burned traces. This was long ago and before the circuit protection idea's had been thought of.

So the moral of this story is don't delay replacing the DCCV. It's a way common failure and is almost guaranteed to happen. It's not very expensive or hard to change but as always with Jaguar. It's a bit fiddly as they say in the UK!
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+1 on the job being very fiddly.

I find it far simpler to disconnect the heater hoses and feed hoses and remove the DCCV from underneath with the hoses attached, then replace the valve and install the hoses on the bench.

Remember to only use constant tension clamps and not jubilee clips or worm drive clamps as they can cause the plastic hose on the DCCV to fail.

 

Hi guys. Here's the rest of my work on my heating problem. I replaced the DCCV, but the problem is still there. I replaced the air conditioning control module. I still have the problem. I ran a diagnostic test and I noticed some problems. I don't have any problems, but when I consult the snapshot data, I noticed problems. When I start my engine, my diagnostic gives me the following information: Driver's air conditioning heater sensor 52° Celsius. Air conditioning post-evaporator sensor 53° Celsius. Passenger's air conditioning heater sensor 52° Celsius. When leaving the engine running with the air conditioning on full blast, the three temperatures easily drop to 42° Celsius. However, I have three other data points that don't change: Data filtered by external temperature sensor 2: 50° Celsius
Data not filtered by external temperature sensor 2: 51° Celsius
Actual interior temperature 2: 52° Celsius. So I think a temperature sensor is faulty. On my Jag, I have six sensors. Two for adjustment on each side (driver/passenger) (XR 82403). The solar sensor (XR81511). The evaporator sensor (XR853162). The exterior sensor in the front bumper (XR85822), and the in-car temperature sensor (???). I know where the driver and passenger sensors are located. The solar sensor is the small ball in the center of the windshield, the evaporator sensor is in the dashboard above the pedals. As for the sensor in the bumper on my control module, it shows me a consistent exterior temperature of 13°C. So, I'm left with the in-car temperature sensor, which is the only one, according to my diagram, to take an "overall" temperature. But I don't know where it is (the small square behind the solar sensor?). I await your opinions.

Thanks,
Marc

 

Hello Marc,

Sorry to hear the problem continues, even after some new parts. To be clear, the symptoms are still the same, right? I want to make sure the new parts are not defective, which sadly is not uncommon.

I'm perplexed by the 50C+ values from the various sensors in the cabin. Were they recorded on a hot day, with the car parked in the sun? If not, I'm perplexed why so many sensors are reading so high. I wonder if there could be a single wire fault affecting multiple sensors.

Per the troubleshooting guide (link in an earlier message), did you try operating the system in manual HI? That bypasses most of those sensors and should give you maximum heat. This is very helpful for troubleshooting. For example, this would help rule out the cabin temp sensor as the possible culprit. If indeed that sensor was inaccurately reading high, you'd get little or no heat in automatic mode. However, in manual HI, you should get full heat.

IF (big if) the cabin temp sensor is bad, details here on how to replace it:

https://www.jaguarforums.com/forum/s...r-dash-220296/

As much work as it is to replace that.sensor, I'd want to rule out all other possibilities first.

 

I am currently experiencing a similar issue. V6 3.0 - no hot air is blowing. I replaced the heater valve and also updated the hoses, replaced the antifreeze tank (it was leaking) and filled it with new antifreeze. I checked the antifreeze temperature and it is normal. I checked all the pipes and they are hot, so I think I've ruled out air in the system. There is still no hot air. I read that I need to disconnect the battery and after 10 minutes start the ignition but not start the engine - in this state, the air flaps are calibrated for 1 minute. If that doesn't help, I plan to find a hill to lift the front of the car and, with the antifreeze tank open, rev the engine to eliminate air in the system. If that doesn't help, the next step is to replace the XW4Z19E616CA and XW4Z19E616AA actuators.