thanks for reply , thats what I thought, just wanted 2nd opinion before I dive in .

 

If your DCCV has failed, consider the following in situ repair:

https://www.jaguarforums.com/forum/s...repair-251854/


I successfully replaced the guts of the assembly, without disturbing the main housing or any of the hose connections.

 

Typos in posts #4 (Insufficient cooling) and #5 (No cooling):

"Hook up your service manifold set and see if the compressor can draw the low side down to approximately 39PSI, which corresponds to 34F at the evaporator."

The pressure value is incorrect. The text should read 29PSI, not 39. Sorry for any confusion.

This is not to be construed as me being wrong, but simply less correct than usual.

 

A couple of quick items to add to the guide.

For the test of the DCCV, in post #2: One method is to compare duct temperature and exterior air, with the AC switched off and manual LO selected. If the DCCV is properly shutting off the flow of hot coolant, and no cooling is taking place, duct temperature should be very close to exterior air. I mentioned "For best results, take these temperature readings during a test drive. This helps reduce the effect of hot air from the engine reaching the cabin air inlet at the base of the windshield." I got to playing around on my car, and want to emphasize what a big difference this can make. While stuck in stop and go traffic, I noticed the duct temperature (both sides) was about 8F warmer than ambient. That's a big difference, and would seemingly indicate a problem with the DCCV. But as soon as I got moving again, the duct temps dropped to within 2F of ambient, indicating all was good. Maybe it was just warm air from the hot pavement. Or it's possible the seal between the hood and cowl is leaking, letting hot air reach the cabin air inlet. I'm not too worried about it, but wanted to pass along this observation. Hopefully it will help somebody avoid condemning a good DCCV.

I also recommend leaving a clip-on thermometer in the center dash vent at all times. This will help you keep an eye on system performance. A friend of mine (another mechanic) saw the thermometer and laughed "Oh, you do that, too!". If the system is working properly, the center duct should get down to approximately 38F when maximum cooling is commanded. But let's say you've got a minor problem, such as a slipping drive belt or low refrigerant. The air might only get down to 45F or so, but that's not always noticeable as it still feels cool. You won't notice it until things get bad, usually at the start of a long trip or some other inconvenient time. With a thermometer in place, you'll catch this minor drop in performance before things get worse. And you can periodically test your DCCV while driving, as detailed above.

 

@kr98664 I joined the forum JUST to THANK YOU! This write up was perfect. My mother just sold her 05 S-Type to a buddy of mine and we hadn't kicked the a/c on in a while. Compressor wasn't kicking in and off to Google I went to figure it out. Found this and got to the point where you mentioned the safety shut off being around 60PSI. 60 is exactly what my gages read (high and low because the compressor wouldn't run). Everything checked out perfect to that point. Dropped in a little 134a to see. Boom! Filled her up to about 40 on the low side while running and she was getting nice and cold. Thank you for the write up!

 

First, thanks for post on S-Type climate control diag you posted back in 2012. I was hoping you had some insight about when a 2000 S-Type 4.0L does not moderate temps. I have full cold no problem, I have full hot no problem. But demand cooler than 84 degrees and the CCM grounds the heater valve full time (hence no hot at all). Also, the cold air by pass actuator seems to only have two positions, 16 and 332 (as seen in IDS datalogger), so it is isn't really blending either. I did recently have the DCCV short out (would immediately blow the fuse) and this is when it all started. I've replaced the valve with a factory new one (one of 3 left in JLR inventory), and have had module masters rebuild my CCM (which did not help), and tried 2 other used ones (new ones are NLA). Output to the DVVC from the CCM does not seem to PWM, ground or open, that's it. Any ideas?

 

Hmm, that’s an odd one. We may want to have the moderators move this to a new thread in case it gets overly complicated.

Have you worked through post #3 above? That’s for erratic or insufficient heating/cooling in automatic mode. Are you seeing any other clues, such as changes in fan speed or switching between fresh and recirc air?

One hunch is a problem with the cabin temperature sensor, the one behind the little grill above the key. Post #3 has a chart with expected resistance values at various temperatures. It’s difficult to see the sensor (see post #22) but it can be read easily from the controller.

 

I am going to pull some known good values from another car, but I also noticed something. It works as normal for the first 15-20 minutes from dead cold, then starts acting up. How? Well it is normal, and then you go to "Lo" (closing the DCCV valves) then back to say 75, it does not moderate anymore. If you go to high, it will go full hot, but back to say 83 or lower degrees, it's cold air. I'm wondering if, once the DCCV get's hot, the actuators either start sticking or the resistance goes way up. Demand = "Hi" would provide full amperage to close the valves, but PWM would not. It's my bet, since there were only 3 of these DCCV's in JLR's inventory left, that they were on the shelf for years. Besides comparing a working car PID's with mine I'm going to take some amp readings on the driver wires to the DCCV.
BTW, thanks for your interest in this.

 

Do you still have the old DCCV that was blowing the fuse? It would be nice to confirm the amp draw and resistance of the two coils. Details here, including an on-vehicle repair method:

https://www.jaguarforums.com/forum/s...repair-251854/

Considering this new problem started with the replacement DCCV, that is a very likely suspect. The lack of PWM? That could be a normal response from the controller as it tries to initially move the valve, but that is just a guess. There doesn't seem to be any true feedback loop for valve position. I know the DCCV itself has nothing to monitor valve position. It's strictly an electromagnet operating each valve and nothing more. I've wondered if the two duct temperature sensors could provide indirect or inferred monitoring of the valves, but I could find no mention of that.

One thing you may need to consider: There's a term called Paralysis by Analysis. It refers to having so much data that it impedes your decision-making process during troubleshooting. For example: the PWM signal (or lack thereof) you're seeing with your scanner. If (big IF) that's a normal output during certain conditions, you may be inadvertently thinking this is a fault. Sometimes it helps to step back and consider how you'd troubleshoot with less information. In that case, your idea of the DCCV acting up when warm makes sense. Wish I had a more concrete answer for you.

On an unrelated subject, was your new Jaguar DCCV labeled Bosch? See the link above showing BOSCH stamped in the two metal covers. I'm pretty sure Bosch was the OEM supplier but am trying to confirm this.

 

Hi, I did face a similar problem on my 2006 2.7D 2 years ago. After probing into it and readiing on forums I realised, being an electical/electronics engineer (but no a car eng) that unless I acquire the basics (knowledge of how this actually works) I am not ging to get anywhere close to solving this and futurre poblems too. This is the best I found which proved to be invaluable.

https://jaguarclimatecontrol.com/diagnose/

Here you have everything you need to know. Please read and follow this and if this does not lead you to solving the problem, please get back to me with your findings and why you got stuck.
One important thing I can say from my work experience and I am now 71, is, forget all that you thing using your logic and reasonong since this is a complex system and assuming this and that in the abscence of luck, will get you nowhere since it is too complex in fact and a corroded conection anwhere (especially if it is a ground connection - (which would upset both left and right of the cooling and heating which end users feel) it could upset or change how the complete system works and mislead you.
SO JUST START FROM From scratch by reading and following the jagclimateconrol guide so that you get Your Current Situaion Facts right..............which then leads to a solution.
Hope this helps.
Joe, Malta.
PS. I will say what my problem was - because it was to complex and misleading to even describe.
What I can say is NEVER BUY HEATER DUO VALVES FOR THIS CAR UNLESS THEY ARE EITHER ORIGINAL OR ONE THAT IS MADE BY BOSCH.
The original and Bosch solenoid plungers are encabsuled in insulation and the contacts reach the outside and remain completely insulated. So the coolant can never get to them and short circuit or draw excessie current. THE COMPATABLES are not insulated and once the coolant reaches them they start drawing more current.
Jauars that do not have the Navigation system - the fuse of the CCM would blow.
But when Jag subcontracted the navigation system, it was built on the same circuit board of the CCM - and they do not have seperate fuse. The fuse remaied one and was uprated to cater for the extra wattage requied by the added Navigtion curcuit.
So if you first replace the Duo Heater Valve with a compatable on a car with Navigation System - (the duovlave being the the first thing that fails on most cars) - the fuse would not blow, when colant reached the solenid valve connection and part of the circuit board burns up without you knowing about this.
So replace the valve again with an original or Bosch - and you think that you are nw worst off, since now have no ac at all.
Anyway I learned all this and more Thanks to and a BIG thanks really to https://jaguarclimatecontrol.com/diagnose/

 

Finally resolved. I decided to step back and look at some basics. Found the right and left duct sensors reading 11 degrees C (set to full cold) and the evap sensor reading 82 degrees C. There is no way the module is going to blend heat into the cool air if it thinks it's already 82 degrees C, unless it's set to full hot, which overrides all the inputs. New senor fixed it.

 

Just now giving this masterpiece a few reads since 2 of my 3 s types dont blow cold air. The 01 hvac works flawlessly but the 02 v8 and the 03 v6 have no a/c at all. Replaced the compressor and refilled the refrigerant on the 4.0 last summer but she wouldn’t cool. Thinking of giving one another go this summer but may try my luck with the newly acquired 03 in trusting the seller that it only needed a recharge. Either way I’ll be an expert by the time summer hits. Thanks

 

More info for posts #4 (Insufficient cooling) and #5 (No cooling):

Check out this recent thread concerning a bad AC pressure sensor:

https://www.jaguarforums.com/forum/s...nition-287096/


The main symptom was the cooling fan running at nearly full speed anytime the ignition was on. The root cause was a bad AC pressure sensor, inaccurately signalling high side pressure over 420 PSI, even with the engine off and thus no compressor operation. (With the system at rest, normal refrigerant pressure varies with ambient temperature, but would be approximately 70 PSI on a 70F day.) We haven't had too many failures of the AC pressure sensor, so it was good to have a nicely documented instance of the symptoms and the fix.

If you have to replace the AC pressure sensor, be sure to have the new one ready to install before removing the old one. There's a self-sealing valve, allowing you to theoretically replace the sensor with virtually no refrigerant loss. However, if the valve sticks and doesn't fully seat, you want to have the new sensor ready to install right away. Any escaping coolant will be very cold, so be sure to wear gloves as a precaution.

 

for comfirmation Karl. You might remember my a/c saga from last year. After line repaired and fully charged a/c worked great for about 10 mins then shut off with cooling fan running at high speed. I remembered that i replaced the pressure switch just because with a new 25 dollar aftermarket. After a static pressure check with gauges i re-installed the original oem ford branded switch and all was well and still is. I do remember on/off quick cycling of a/c compressor until it just remained off with the faulty aftermarket switch. These cars really prefer oem electrical parts

 

If you've noticed a temperature split, with the ducts on right side a little bit warmer than the left, in both AUTO and MAN LO, take a look at the following thread for an important discovery:

https://www.jaguarforums.com/forum/s...problem-290258

In a nutshell, if the refrigerant charge is a little low, apparently the evaporator tends to perform better on the left side. Remember, normally the evaporator operates at a single temperature, and fine tuning side to side is done by adding heat via the heater core and DCCV. Unlike the split heater core, which can heat the two sides differently, the evaporator is not designed to intentionally cool one side more than the other. It would seem it just works out that way, cooling the left side more than the right when the charge is low.

If you do experience this condition, you must still check out the DCCV thoroughly, as detailed in post #2 way back near the beginning of the guide. Please note these tests only make sure the DCCV is not allowing unwanted heat into either side of the cabin, by comparing ambient and vent temperatures when the heat and AC are switched off. When writing the guide, it never occurred to me to make sure both sides of the evaporator were cooling the same amount:

https://www.jaguarforums.com/forum/s...2/#post1714570



If those tests pass, and the right side is still not cooling as well as the left, make sure the refrigerant level is correct. Details in post #4 above:

https://www.jaguarforums.com/forum/s...2/#post1714573


Many thanks to scottjh9 for taking the time to share his findings with us. The subject vehicle was a 2006. I can't guarantee this information applies to pre-facelift models, but the evaporator part number is the same.

 

thanks karl. I think i got a little lucky and backed into the fix. Everything else on the a/c system was new within a year or eliminated via diagnosis. My hvac friend did say that use dupont refrigerant if possible. They are inventors of it and have strict quality control. He knows bulk 134a is available but not sure about small cans