Oh, and Karl, I managed to get through your novel.
Some good points to note in there. Especially about the AC.

 

Right then, here's where we are now.
Checked for voltage at fuse number 1 in the engine bay = nothing
Pulled relay No5, jumpered pins 3 and 5, pump fired up.
Checked for voltage at the centre pin of the DCCV connector = 12.60v
Plugged the DCCV unit in, switched the HVAC to high to command the valves to open fully = no movement
Switched HVAC to LO = no movement of the valves.
Un-plugged DCCV unit = no movement of the valves

Conclusion = DCCV knackered

Other thoughts = why no voltage, ignition on or off, at fuse No1 in the engine bay?

 

Found a new DCCV at my suppliers, genuine Jag part, £118.00.
And he has it in stock.

Ah well, the things shot so it'll have to be changed I suppose.............

 

I'm not sure why you saw no voltage at the fuse, yet you had full power at the center pin of the connector. Might be a testing issue, and something of a moot point since you saw voltage where it's needed at the connector.

If you really want to get crazy, rig up some small FUSED test leads and apply 12v directly to the DCCV at your workbench. Supply +12v to the center pin and then ground an outer pin. The valve on that side should close with power, and spring open when power is removed. A quick test like this will rule out any faults in the control circuit.

On your DCCV, can you determine the positions of the two valves? If they are currently stuck closed, that should give some confidence that a new DCCV is needed. Even if you can free up the valves and then get it to bench test okay, resist the temptation to reinstall the old DCCV. The only way I'd reuse it is if you realize you had previously made some error testing it on the vehicle and it bench tested fine every time. Even then, I'd be hard pressed to reinstall an old one because of their high failure rate.

 

Hi Karl,
I stripped out the DCCV on the bench, the valves were stuck closed.
No crud in them, just wouldn't move at all.
After reading the other post I linked to, and some other stuff, I did the bench test, 12v to centre, earth the outers to see if anything moved, got nothing either way, so conlcuded the DCCV is shot.
What I have done now is stripped out the valves, removed the inner valve slides totally so just the pin is in there, making the unit completely open as it should be with the connector off and not powered.
The next bit I did just for curiosity.
It's all back on the car.
Yup, I re-installed the DCCV, pump, hoses, everything.
It's not a major job really.
Re-filled the system, burped it as best I could, ran the pump with the engine off for 1 minute to get at least some water into the matrix and hoses, started the car and let it idle until the needle is at the centre of the gauge. Then ran the car at 2000rpm with the pump jumped on the relay.
The lower return hose from the matrix was getting as hot as the top rad hose, and the two flow hoses into the matrix started to get a lot warmer than they were previously.
There was also a noticable amount of warm air coming out of the face vents in the cabin, although not baking hot just yet.
I monitored the coolant temps with the OBD scanner and just as it satarted to get to 195 degrees you could here the rad fan start to pick up just a little bit, not a lot, but a little.
I'm happier with the results obtained today, I will flush and backflush the matrix over the next couple of days when other work permits, before I fit the new unit.
Hopefully it was just the DCCV that was causing the problems and nothing else.

 

Wow, great stuff. I'm especially interested in the postmortem of the DCCV. Any idea why the two valves were stuck? You mentioned everything looked clean. Maybe the seals were swollen and that caused the binding? Was there any coolant in the dry side of the solenoids? Maybe that could have caused hydraulic lock and defeated the spring action.

Your DCCV failing closed is very unusual. The typical failure is open, due to the springs. The reliability of the DCCV is so poor, any further details, hunches, or crackpot theories would be very helpful.

 

There was some liquid on the electric side of the DCCV, one of the them had a lovely puddle in it.
They didn't slide out of the housing easily though as I had expected them to, so probably a seal failure as you say.
It may also have been one or even both of those little diode type thingys that are in there also.
I did rig the pump and DCCV using a bucket of water to see if anything would come out the flow side but no joy there either.
After I removed them valve slides I did the same again and got flow from both outlets.
Strangely enough, the internals "look" fine. As I said, no crud inside, so the only conclusion I can come to is either seal failure through swelling as you say or electrical failure of the windings and electrical diodes. Or maybe even both given the valves were closed.
When I get some spare time, I'll see if I can get any readings from the windings and connections, I like digging into mysterious failures.

 

Phoned my supplier on Monday for the new DCCV, he did a physical check of the stock, couldn't find the part on the shelf. So they ordered one in for me which turned up yesterday.
I'm hoping to make a start on it today or tomorrow, in between re-spraying a 1966 Lambretta for a customer that is.
Once it's in, I'll perform a post-mortem of the old DCCV and see if I can ascertain why it failed.
Better go and un-ravel the hose pipe now ready for the forward and back flush of the matrix.......................
Still thinking about that no power thing at fuse No1 as well.

 

So some progress, but still a little miffed.
Tested the new DCCV on the bench, both solenoids clicking into place as they should.
Tested the connection plug again, just to be sure, 12.6v at the centre pin.
Tested for continuity (on the harness plug) down to earth at each of the outer pins with the HVAC set on manual low settings. Internal fan speed at minimum. Got nothing. No continuity to earth.
Plugged in the new DCCV, ignition on, HVAC set on low, internal fan off, expected the solenoids to click closed; nothing.
I've also still got no power the the auxillary coolant motor, although I have sorted the power at fuse No1, just a dirty connection.
Thinking I might have a dodgy relay I swapped it for the front driving light relay out of socket 7, being the same type, still no feed to the pump.
So I started to trace the wiring back to the engine fuse board, bugger to get the board up and look underneath, but all appears fine, no corrosion or loose terminals that I can find.
Looks like the multimeter is coming out for a good probing session.
Printed out the wiring diagrams for plug sockets, connections, pin numbers, locations and all that stuff.
Been sitting here going through them to get all the info I need to start tracing any faults.
I have to admit it's becoming an education to track and trace all these connections on this car, and understanding Jags coding, I've got multiple pages open on the PDF's, however, if I start with continuity tests through the wiring I should be able to pin point the problem(s).
(he says)

 

Well now...............I have no idea what just happened.
I may have been chasing a ghost.
When I went back out to the car to start the electrical testing, I thought there is no point having the radiator shroud, top hose, pump, DCCV all still out the car, so I put them all back in, hooked up, re-filled the system, ran the pump (bridged the relay) for a minute to get the water round the system and burp it.
The battery had to be charged for an hour or so, so I stuck that back on and fired up the car, just to make sure there was enough juice back in the battery.
I set the heater on manual, on high, blower fan on full, on the face vents.
Within a couple of minutes I am getting very hot air, very nice and toasty indeed.
So now I know that the water is getting through the matrix and round the engine.
Remember what I said about not getting any continuity from the DCCV earth pins?
Well if that was the case, then the solenoids would not close and I would not get cold air into the cabin.
I turned down the heat to minimum, blower fan still on full, and I could feel the inside temp dropping very quickly.
There is no A/C in use at the moment.
So I turned up the heat again, everything responded as it should.
Turned it back down again, fantastic.
The valves in the DCCV must be working as intended, otherwise I would not get the temperature response I've got.
I checked the 3 lines into the matrix, both flow pipes are too hot to hold, as is the return pipe.
Quick look at the radiator fan, I noticed that it wasn't turning at all, and the car had been running (read idling) for at least 8 minutes by now. I was at least expecting it to be turning slowly.
The temperature gauge on the dash took a while to get to the middle mark, but when it hit exactly the centre of the gauge, the rad fan started to kick in slowly.
I'm going to monitor the coolant temps through the OBD, just to see where it's sitting in real time, plus I will be able to see and hear where the rad fan starts to kick in fast and what effect it has on the cooling.
Hopefully I'm not jumping the gun by saying it's sorted....................

 

Hmm, my first thought is to wonder if checking for ground is actually a valid test. If I had suggested this, I'll deny everything so there's no point trying to blame me. Maybe the control module is so smart, it won't send a command if it doesn't detect continuity through the DCCV. Not really sure, just thinking out loud. I've learned when a troubleshooting step indicates a failure, but the obvious fix doesn't work, it's often worthwhile to step back and question all assumptions.


Here you've got the fan off, while in the previous step it was at low speed. Could that be part of the equation?

Have you investigated burnt traces in the ACCM? This is more common on 2003+ models, but maybe you have the same problem.

DIY: Diagnose It Yourself - JaguarClimateControl.com

 

All seems to be working just fine.
DCCV is doing what it's supposed to do.
Just been monitoring the coolant temps via the OBD.
Running the car for 15 minutes or so, stationary.
Temp got to 190 degrees F, rad fan kicked in, working at "normal" speeds.
Temp rose very slowly to 214 degrees F, rad fan got faster
Hit 216 degrees, rad fan went to fast mode (I could hear it with the window open)
Temperature never went any higher than 216 degrees, rad fan bought it down within 1 minute to 208 degrees.
Inside of the car is proper hot now, I won't be freezing my particulars off if we get a hard winter in the UK this year, and if we don't get a hard winter I'll still be on the bike anyway.
My only little concern is that I can't feel the auxillary pump working when I put my hand on it, as you can when you bridge the relay contacts.
I may put a hidden switched and fused connection inside the car for a while, at least until I'm 100% satisfied that all is functioning normally.
Now that I've had the fuse board out, it's quite easy to tap a spur in there to the underside of the relay pins.

Karl
I was going to start tracing through the system for broken wires and bad earths, the next step would have been looking for burnt traces in the ACCM, but it certainly appears as though the ACCM is a smart unit, and not giving out signals unless the other parts are connected fully.
It could well be that the ACCM wouldn't actuate the earthing to the DCCV until it received a signal from the HVAC unit, whether or not the signal would come from the fan actuator is another matter.

As I think you previously said, this dual system is not like any other heating/cooling system that has been worked on by us mere mortals.
It is most definately the first dual system I've worked on, and all the knowledge that I have gained is by the information found on this forum and my own fumblings.
When other members post their own problems, and find the right solutions, it is so much help.
And links to things like wiring diagrams and module locations that can't be found in the JTIS, are an absolute godsend.

 

From a Jaguar training manual, this should help explain when the pump is commanded to run:

 

I'll be using that one a bit later then
I had already seen that in another post but hadn't printed it out, thanks for the reminder.

 

Well my fears have been put to rest.
I thought that the auxillary coolant pump was getting a positive feed to enable it to pump coolant round the engine and cabin bays properly.
I was going to put a hidden switch into the cabin so I could manually turn it on if I needed it.
However, after KR98664 posted this in the thread, it sent me on a test mission.
Just done the test, took a video for you all to see.

The file is too big to upload here so I've posted it on UTube.

 

Had some time tonight to look at the old DCCV unit.
There was some fluid in the coil side and I quite expected that to be the cause of the failure. However..........
Both the valve needles move quite freely by themselves when powered, and a fair distance to boot, so much so that I would say the unit is good.
So I put the valve slides back together, exactly the same way as they came off, and in the same pots.
When it came to putting the assembled unit into the housing it was practically impossible to get it to seat all the way down, even with the aid of some lithium grease it would not slide home fully enough to get the screws back in.
So I took one of the slides off and tried that by itself, sliding it into the housing, absolutely no joy, would not go to the bottom at all.
Tried the other slide, exactly the same.
Tried them in their opposite sides, no go.
So there are two possible conclusions here that I can see.
1. The lower seals have swollen to an extent where they lock themselves to the housing
2. The housing is warped internally towards the bottom of the valve hole.

Any other thoughts on this would be welcome and I still have the DCCV sitting on the bench if anybody wants me to check anything else.