I agree with the reason George stated - it's due to the casing being both metal and plastic, fused together (not very well, it seems). Go to an all-metal casing and these DCCVs would last much longer I'll bet....

 

Hi Daniel/all concerned

I have the same issue on my v8, 2000 stype.No heat, a/c cooling is fine. since i live in CA, heat problem was not a major issue. Before dishing out $$$ for DCCV( 195/-rockauto), i want to make certain, outputs from the climate control module(CCM) is good.With the help of my wife, while adjusting to hi heat,using doctorscope(ste-cope), was trying to listen to solenoid clicking on the DCCV, but did not hear anything.with the scope was listening for aux pump function, it was ok.With engine hot(stopped), tried to manuver my hand to reach the DCCV plug.it was not easy.i wanted to plug the AVO to the plug and check for volatge when the CCM inputs DCCV to open.I fail the task because, i cud not reach it.1.Is there any other place to plug the AVO to check the inputs to the DCCV? 2. What are the indications when the CCM is shorted out?my one seems ok.Please advice.

reading here, it is cumbersome, to take the CCM out? If we can brain storm a shorter way to check power to DCCV, we will help most our members,prevent wasting money and time on DCCV replacements.Reading on the blog,very few were successful fixing the issue with the replacemnet of DCCV.

Daniel?brutal, can you guys please shed some light here, how to remove CCM, and wiring checks ascertain signals to dccv.
Thanks

 

You can check the power out of the CCM at the back of the CCM Connector, OR at the DCCV Connector - which you seem unable to get to. I attached the Wiring Diagram with pinouts for the CCM for your 2000 S-Type.

George

 

Lots of insight and collective wisdom emerging in this thread. I think I can chalk mine up to the leak fouling the circuitry. I will see if I can tell where the leak came from when I get the part back from the shop doing the work (luckily, mine is warrenty also, but they have to have it approved by Jaguar before doing the work - is that specific to DCCVs or is that true for other jobs too?).

Thanks for these and the related comments:
The externally leaking ones fail in a different way. Somehow they are spilling coolant OUT of the valve. Either from the seal between the ABS and metal portions of the valve, or from a crack somewhere in the valve. Somehow coolant is making it to the outside, initially slowly, and sometimes in large amounts...

That probably makes sense as far as how coolant gets into the electrical side of the solenoids and shorts them out.
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So, the different material thesis sounds about right. Some get an internal leak that shorts out the unit while others get an external leak (or seep in my case).
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Actually the internal and external leaks are from the same set of seals. It just sometimes leaks more one way or the other. Not sure why or how??

 

Looking at the valve and it's construction, I disagree with this theory.

The valve is actually two pieces, a top metal piece that encompasses the solenoids as well as the bottom abs plastic piece which has the barbs for the hoses to the heater core and from the upper radiator hose matrix. These two pieces are held together by 6 small torx screws - typical Bosch, same thing they do with their ABS control units. The two portions of the valve are able to be separated once those screws are removed.

My reasoning:

If the internal seals fail on the solenoid, it would allow water to seep past the plunger if you will which closes the valve, and up into the electric actuator, causing the valves to short and permanently stay open (as coolant is drawn in past the seal to short the actuator as the plunger retracts). I assume they are in a normally open position, blocking coolant from circulating through the heater cores unless desired, and retracting when power is applied to enable coolant flow. This mode of operation would make more sense than having them electrically activated to prevent coolant flow from the valve.

The valves that leak coolant outwards, seem to do do from either the seal (which is a gasket) between the ABS portion of the valve and the the metal portion. Not only is the coolant pressurized by the temperature change of the car (remember the cooling system is sealed), but there is also an additional aux electric pump to push coolant into the heater cores.

I think the valves are prone to failure in two separate ways, and that the problem you experience is dependent on the failure. There have been several reports on here of valves like mine, leaking externally, with no adverse HVAC issues, and antecedent reports of HVAC failures, or constant hot conditions, with no external leaking.

This isn't a Jaguar Valve but is a BOSCH valve out of a BMW - The 3 series uses a single valve (no dual zone controls) Look at the mating surfaces here and it should make sense.




George

 

Hi George

I agree with the valve ops you have mentioned.More specifically, these soleniods are de engergized closed( term use is cold solenoid) and energized or plused to open, for the coolant to pass to the heater core inside the car.This way it prolonged the life of the solenoid, as it is hot(energized) only for few a seconds.By the way thanks for the wiring diagram

 

I have had the same problem forever now. If anyone can tell me where the sensors are and how to get to them I will replace everyone. I replaced the DCCV and no luck.

 

The cabin air temperature sensor near is the ignition-key switch. That probably doesn't need to be checked or changed.

The evaporator temperature sensor under the driver-side foot well is shown here:






There are a couple more at the passenger-side foot well.

 

No. You definitely should check the sensor above the key switch!!! The air flow from the cabin is drawn over this sensor and it will build up crud. I have removed and cleaned several. All very dirty especially if the car has ever been smoked in!!
Plus it is cheap and easy to do. I always do the easy stuff first before changing parts..
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Sorry, I should have referenced the symptom that willsmith11111 has been experiencing, which was actually from a different thread:
https://www.jaguarforums.com/forum/s...4&postcount=27

The symptom is described as: "...The a/c works a little bit until the engine is hot and then it blows hot air. I replaced the DCCV and the a/c worked for a few hours and then it went back to blowing hot...."

Sure, it doesn't hurt to check the in-cabin temperature sensor, and I totally agree that checking the simple things first is a good practice. However, the symptom as described in this specific case doesn't exactly correlate too closely with a typical in-cabin temperature sensor failure mode.

Instead, it may be more efficient to tackle the problem based on the symptom. If we know what the symptom is, and have an idea how each component functions and what might happen if any one component fails, we can narrow down the possible sources of the problem and perhaps arrive at a solution sooner. Anyone with this particular symptom should be asking the question, "why does the a/c work only until the engine is hot?" Anyone who went through the trouble of replacing the DCCV should at least make sure the new DCCV is getting the power and ground signals it needs for normal operation.

 

If the A/C works until the car warms up, chances are the dccv is stuck open and there is coolant flowing through the heater cores. The ac appears to work fine until the coolan comes up in temp and then the cold air is tempered by the heat building up in the cores, and the cooled air is being tempered by the heat. Essentially you have the heat and ac on at the same time...

 

If this is your problem you can do another test to make sure. Pinch off the heater hoses. If the A/C now works we can be sure the DCCV is leaking or not operating properly. In fact if you can identify the hoses, which is not that hard, all you really need to do is clamp the input hose to the DCCV closed. You want to clamp off the small hose that is attached to your upper radiator hose. This feeds the DCCV and is sorta easy to get to on the 4.2 L V-8.

Remember the DCCV could be bad or it may not be getting the correct control signals if you have a A/C module problem.

Here are 10 pages from the Jaguar JTIS (2004 Model year) about engine cooling. Has some great diagrams showing all the heater hoses for the V-6, V-8 and STR. I do better when I have printed material in the garage. My memory is not trust worthy anymore!!!
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Bob, thanks for posting the procedure for replacing your control valve. It seem as a new member I can't open it now. But after 10 of these I can come back (or so I understand it.)

 

Yes, about 10. There's a newbie place and I think an off-topic that may help. Oh, and Hello!

 

Or go to the new member area and introduce yourself and vehicle. JimC64 (admin) may just jump you up to a full member.

 

good info same here just posting so I can access thelinks

 

Oh! sorry forgot 2004 STR

 

great post, i've been reading through the forum to learn how to replace my DCCV valve and this was extremely helpful. Now just posting enough so I can hopefully get access to the JTIS links.

Thanks!

 

I can't access the provided PDF. Is there something special I need to do? I just joined the forum..

 

Hey Bob; Mine went south about a month ago and I found a good one (new I think) on Amazon under "Bosch heater control valve". I would also check Ebay if you haven't already done so. I've been pretty lucky there.

Truman