I have a 2002 lr disco 2 with rear air but it’s not blowing. I’ve exhausted my ability to find a fix so hoping others can point me in the right direction. I’ve researched, read and watched everything I can find related to my issues and can’t seem to piece it together. I feel like it may be a wiring issue at the passenger fuse box or wiring in the rear blower harness. I have a basic understanding of the wiring diagrams but there are some notations I don’t get so hoping I can get help with the ac and wiring issues altogether.

In summary the rear ac was not working so I went down the familiar rabbit holes. the wiring in the passenger fuse box is a mess. There are splices into the box and random wires I can’t tell where they are coming from so at minimum I’d like to understand what they did and ultimately restore it back to the original configuration. More pressing I’d like to fix the rear air and then work my way through the other wiring issues. The car runs and has no other electrical issues to my knowledge so I may be poking a bear. Onto the ac…

The front air blows. The rear does not on any speed. The rear ac switch does not illuminate when the button is pressed so thinking the switch may be the issue. I do not have another to test that theory. Is there a way to jump power to the switch? There is also questionable wiring in the rear blower, more on that below.

What I’ve done

• Bench test relay and blower (they work)
• Install new resistor (previous owner must have removed it)
• Test engine fuselink 4 (no issues)
• Fuse 6 and 7 have power when car is running. I have 2 spare fuse boxes that I’ve resoldered to swap in if the solder joint has gone bad and that is the cause of the issue.

Current Status
Wiring on C856 is funky. There is a 40amp fuse in the left hand rear compartment noted on the resistor pack but I can’t find the prototypical fuse. I did find an inline fuse case connected to the WG wire on pin 4 of C856 but have never seen a fuse of this type before. Is this the fuse the manuals refer to? The image in the manual shows two white cases so I seem to be missing one and am not sure if the one I have is wired in the correct location.

I also have no BU wire coming into C856 but there is some weird loop where there are 2 U (blue) wires on pin 3. One of them goes to C425 and the other loops to the fuse and then turns into the WG wire that goes to pin 4 on C856. That ain’t right, at least it doesn’t seem like it.

Any ideas on what to do next would be appreciated. I’m in Phoenix so as you can image rear ac is very necessary at this time of year.

wiring diagram and wiring questions
On the wiring diagrams there are black dots with alphanumeric notations I can’t figure out what they are or where to reference more detail about them.

When a wire terminates with a zigzag line and a letter what does that mean? How do I trace where that wire is going? I’m assuming the letter is a key for where to pickup the line but I make sense of it.

Lastly and this seems dumb to ask but I’m going to ask anyways, When you have two mated connectors do the wire colors always correlate with each other. On most connectors they seem to but for example on C692 and C856 all of the wire colors are identical on each pin except pin 3, on C692 it’s a WG wire and on C856 it’s a BU wire. Also pin 5 on C692 has a BG wire but C856 has no wire at pin 5. What’s the point of having a wire that terminates at a connector. Would it make more sense to have the wire terminate at the last part that needed the wire?

 

I'm still trying to wrap my head around the entire situation here but in the short term I can help with this one. Scroll three pages up and look for the corresponding A & C on the right hand side.

 

Line J comes from page 38.2 on the left hand side, it goes to the hvac ecu, basically the hvac ecu provides the ground for the relay.
Line A and C come from page 38.1, C is fuse 31 hot with ignition on, A is fuse 6 hot at all times

Ok, back to basics on troubleshooting this blower circuit. As I understand it the issue is the blower does not work in any setting, so the issue is a basic one not an issue with the resistor pack or rear blower switch intermediate positions. So here are the troubleshooting steps I would recommend:

1. Turn all switches on, on high. Check for power on the brown wire at the blower, check for ground on the green wire on the blower. One or both will be missing.
2. Depending on what is missing, power or ground or both, start to trace it out. Check for power at the Rear blower relay on top of the rear AC housing, connector C817 at pin 2 and 3. Pin 3 is fuse #6, Pin 2 is fuse 31. Check for a ground on pin 1. (HVAC ECU). While there, you can jumper pin 3 to 4 and see if the blower runs. Pin 5 should be ground if that helps secure a ground test point.
3. If you are missing power at one of the hot pins, look at the fuses and you can check the intermediate connectors to see if you have a break in the wiring somewhere. If you are missing the ground pin 2, check your switches per below. Missing on pin 1, check the intermediate connectors or the back of the HVAC Controller
3. Check the rear blower switch Connector C0696 - check for ground on pin 5. Check pin 2 has continuity to pin 2 at C0425-2 on the resistor pack connector, pin 3 to pin 3, and pin 4 to pin 4. Check the switch and make sure pin 1 connects to pin 5 at all times, and to pin 2 in position 2, pin 3... etc.
4. Check the rear air switch connector C0695, make sure pin 4 is grounded with the air on (you can check with pin 5 on C0696). Make sure on the switch pin 1 has continuity to pin 4 when the button is pressed. Make sure pin 1 has continuity to pin 1 on the rear blower switch connector C0696.

The green highlighted fuse question mark is the diode G126.