I removed all three temperature sensors and checked their resistance.
Also compared the data to what was reported by others on the forum.

The left and right duct sensors each measure 25k at 85F while the evaporator sensor is showing 30k.
I put all of them in the fridge and the one removed from the evaporator sensor position gives a higher reading (10-20%more then the ones from the ducts).
Am I correct in assuming that the outlier is the one to be replaced?
Motorcraft YH1504 sensor is available for about $15 from either Amazon or Rock Auto.

 

Yep, it looks like your evaporator sensor is bad. Post #3 here has a chart of resistance values:

https://www.jaguarforums.com/forum/s...2/#post1714571


What symptoms are you experiencing?

 

Any updates? I'm curious what problem you were experiencing and if a new sensor fixed it.

 

My new sensor is arriving on Wednesday. I'm also getting the climate control circuit board repaired. Will give an update when all of this is done.

 

I think my climate control system has multiple problems!

I received the new sensor.
Got rid of the old evaporator sensor. Kept the driver and passenger duct sensors.
The resistance of all three were now very close.

A little background:
While my climate control unit was being repaired (burned trace) I decided to take the sensors out as I was working around the dashboard anyway.
From what I remember the automatic part of the climate control never worked great; it had trouble keeping in-between temperatures (between LO or HI).

The climate control unit burned out one day when I wanted to demist the windshield using AC plus heat.
That's why the circuit board had to be repaired.
(The DCCV has also been replaced with a Motorcraft unit)

So I just got my board back with the circuit protection upgrade and put it back in.
The AC cools quite well in LO mode. Vent temperatures are in the low 40s.

But, when I set it to 67F the vents started blowing hot again.
Fuse F32 was blown immediately when this happened.

Replaced the fuse and tried the AC at the LO setting and its cools the vents again into the low 40F range.
I bet it would blow the fuse again if I changed the setting a little higher as I did yesterday in my testing.
So there seems to be an over-current situation but I don't know what to do next.

Any input is greatly appreciated.

 

I can think of only 2 overcurrent causes:
1. bad DCCV
2. wiring fault

Your fault does not appear to be #2.

 

Could be, but don't despair. Fix one fault and then move on to the next. You'll get there...

That could be as simple as one of those three temperature sensors having been out of range. You may have already fixed this without realizing it due to the new fuse issue.


This is good news. This narrows down where to look.

I wonder if the fuse blowing was related to changing the panel from LO to 67 (not super likely) or if it was just a coincidence after having operated for a certain amount of time. See figure 01.2 for problem child fuse F32:

http://www.jagrepair.com/images/Elec...al%20Guide.pdf

That fuse feeds only three items:

DCCV (figure 06.1)

A/C compressor clutch (figure 03.4)

Aux coolant pump, V8 only (figure 06.1)


I suppose you could have a wiring fault (bare spot rubbing to ground, for example), but I'd suggest looking at those three loads first. Rule out the easy stuff first. Maybe buy a pack of fuses and see what happens. You could also use an ammeter, but if connected in place of the fuse you lose overcurrent protection.

I'm not sure the aux coolant pump would have been running when the fuse blew, but it's easy to isolate. Remove relay R7 at the front power distribution box to remove power to the aux coolant pump. Keep a close eye on the coolant temperature, because in an overheat situation this pump will kick in for protection, but you should be safe to disable it briefly for troubleshooting.

If the fuse keeps blowing, reinstall that relay and move on to the next easiest item, the AC compressor clutch. At the front power distribution box, remove relay R8 to remove power to the clutch. Obviously you will lose AC, but everything else on that fuse should remain powered.

If the fuse still keeps blowing, reinstall that relay and move on to the last item, the DCCV. The only way I see to disable it is to disconnect the electrical connector. Both internal valves will spring-load open and bake the cabin, but hopefully you won't have to do this too long.

If the fuse now remains intact, the new DCCV was the problem. If the fuse keeps blowing even with the DCCV isolated, you've probably got a wiring fault somewhere.

 

It's not the first time this fuse was blown.
I had to replace it at least once.when I bled the cooling system after a component replacement.

Just before I read your post, pulled both R7 and R8 and checked the contacts and coil resistance.
Both looked okay.

A few months ago also checked the connector under the bumper for corrosion.
Looked very clean.

Will do systematic checking as suggested.
Going to have to buy some fuses, ha-ha!

Hooked up the iCarsoft LR v1.0 :
B2426 passenger solar radiation sensor circuit open
B1265 cool air servo motor circuit failure
also U2518
These may have been stored from the time when the circuit board was removed.
I might clear them and restart to see if they reappear.


Thanks,
Gabor

 

A quick note: Don't be discouraged if the fuse problem seems to be severe. It's MUCH easier to find (and correct) a hard repeatable fault, versus chasing an intermittent one that can't be repeated while troubleshooting. Keep us posted
​​​

 

First test :

Removed aux pump relay. Ran car with AC, took it on a 2-3 mile ride.
LO, HI and Intermediate temperatures worked fine and the fuse did not blow.
Coolant temps (monitored via iCarsoft) went from 86 to 91 Celsius and back to 86.

Second test:

Swapped aux pump relay with horn relay.
Put the system through its paces again and the fuse hasn't blown yet.

The horn beeps so the old relay is not dead.
But, I'm going to leave it as is and will give an update if anything changes.

 

I went through this a few yrs ago. In my case one of the duct sensors was out (bench tested after removal) and the ambient sensor was the main problem. Once I replaced them all everything worked perfectly and still does.

Here is my post:
https://www.jaguarforums.com/forum/s...r-dash-220296/

 

Thanks for the reply.
I read your thread on the ambient sensor and thought this was beyond my skill set. But, I'm more experienced now, having gone through a few more repairs since then. Might tackle it at some point if I'm still having problems. Right now the weather is so hot the system is always set to "LO" anyway.