2005 S 4.2 NA 113,000 miles

Back in 2016 I had A/C problems which with the help of the forum and my independent Jag repair shop I was able to fix.
After replacing all the sensors, the dual coolant flow valve [heater valve?], Recharging the system, Evaporator discharge temp sensors and having the CCM unit repaired and upgraded by Jeff at Jaguarclimatecontrol.com it still did not work. Finally my mechanic found a broken wire at the harness connector and repaired the wire and it has functioned flawlessly until today.
After being on state ordered lockdown for the past week or so I ventured out to pick up RX's on a warm 60 F day in metro Detroit. The air blowing out of the heat vents was rather warm. I turned the A/C on and lowered the temperature - hot/warm on drivers side - cool/warm on passengers side. Checked all the fuses and fiddled with the controls - still persists.
The question is --------- before I start digging into all the components again I was wondering if someone has experience on the rebuilt/upgraded CCM from Jeff. It is my understanding that the factory CCM did not have a fuse in the unit and they would fail, the upgraded unit has some sort of fuse to prevent this? If so is it possible to open the unit and check the fuse or whatever they do to upgrade the unit?

 

I did a bit of research and found a post on the forum that claims if the dual coolant flow valve fails after you have installed the upgraded CCM the upgraded CCM shuts down all communication to the dual coolant valve until a new valve is installed. Does this sound correct? Just trying to do a bit of troubleshooting before I tear into it as I remember the frustration the last time I worked on this problem.

Thanks all - on to barley therapy!

 

Define "correct".

See this thread, post #5, for pictures inside the upgraded CCM:

https://www.jaguarforums.com/forum/s...4/#post2205597


The first two pics show the added components for circuit protection. Those are basically auto-reset circuit breakers, although it may be more accurate to call them current limiters. I'm not sure what the current rating is, but when exceeded, those open and cut off the power. I've tried to find more details of exactly how those doohickeys work, but my best guess is they close again automatically. The circuit powers up again and if the overcurrent is still present, the doohickeys open up again and turn off power. I do not know how quickly they cycle. They may cycle quickly enough to basically apply steady(ish) power without exceeding the current rating. Or they may cycle on and off, as if flipping a switch back and forth, with noticeable pauses in between. Regardless of the details, I'm pretty sure they automatically reapply power. Install a good DCCV and it should power up normally, with no other action required.

There's no need to remove the module yet and open it up for inspection. I would highly recommend starting here instead, and work through the troubleshooting guide based on your present symptoms:

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


Specifically, start with the test of the DCCV as detailed in post #2. All you need is a $3 thermometer in the dash vent. If it passes, the control module is fine and there's no need to look inside. If the DCCV test fails, the guide has some very basic wiring checks, to help determine if the DCCV is bad or just isn't getting the signal from the control module.

 

Karl,
Thanks for the explanation and the links to the troubleshooting guide/pictures. As you explained the "circuit breakers/current limiters" make sense and since fuses are not used removing the CCM at this point is not necessary [I've had it out so many times in the past that it's no longer that big of a deal]. I'll start with the easy stuff and work my way through the guide [I also have one provided by JaguarClimateControl] and start calling around for a DCCV. I believe the last one came from my local Ford dealer - will have to check the file and see what's open during our "lockdown".

 

Those doohickeys are resettable fuses. they open if the current exceeds 1 or 2 amps and stay open until the short disappears

 

I ordered a handful of these little doohickeys (sorry if I'm getting too technical). Curiosity got the better of me. I plan to play around with them and see exactly how they behave, especially what it takes to reset them.

 

here u go

https://en.m.wikipedia.org/wiki/Resettable_fuse

and https://m.littelfuse.com/~/media/ele...asheet.pdf.pdf