Disco 1 Blower not working. Almost got it pinpointed down.

Afternoon folks.
So a while ago my heater blower unit packed up. No settings 1 through 4 would work. So I figured I would buy a replacement because I had heard its probably the motor itself seized or something very closely related. Pulled a lot of the dashboard and glovebox to take a look and after much searching and replacing things discovered the following.

All fuses from under the bonnet to the blower work fine.
Blower motor does work and is not seized. Direct power does activate it.
Resistor pack works fine.
Relay is working fine.

I just need a little help working out the relay.
When I apply power to the blue / red wire that goes into pin 86 of the relay next to the blower. Everything works as expected. The blower fires up and the switching controls all work from one to four. Hence how I know the fuses work, the relay works, the blower works and the switching control in the centre of the dash works.

So I have to presume that a) pin 86 is supposed to get power from somewhere as its switched power that clicks the relay coil and b) it isnt getting that power.
The haynes diagram is fairly simple to follow. The blu red wire comes from the air circulation solenoid but I have swapped that out and that did not work so unless I have two bad ones I cant see it being that. And then on the other side the blue red wire turns into a green white wire (at a point I cant find) and then goes to a bunch of relays that are all to do with air-conditioning from what I can gather. As the car is non-aircon I wondered how much this would matter if one of them didnt work but I replaced them all anyway and still nothing.

So how does that pin 86 blue/red wire get its power? Am I looking in totally the wrong place for what is causing this?
I really would like to not have to bodge this if possibly and just feed it permenant live.

Many Thanks.

The blower relay coil receives a 12v supply from fuse15 (10amp) dash fusebox to the relay terminal 86.
The blower relay receives a 12v supply from fuse MF2 (60amp) engine bay fusebox to relay terminal 87.
The relay is switched from terminal 85 via the dash slider switch, and completes the circuit to ground for the blower motor, also in any of the four operating switch positions.

That’s about it basically, but a lot more info can be found in the LR electrical workshop manual for the D1, which can be downloaded.




Sent from my iPad on a train.

Hi, thanks for the reply. I figured the switch panel was just grounding as thats what the haynes diagram looks like. The oddest part is I have check all the fuses and non of them are gone. Power goes to the fuse and even passes through the fuse when checked. So perhaps it is a dodgy wire from the fuse to that relay coil terminal. Something crushed or rubbed bare or snapped possibly but somewhere along the line that blue/red wire is broken. I really do not want to take the dash out and follow the wire but its looking like the only option it seems. Either that or no blower. Winter demisting will be fun
Another option might be to just run a brand new wire from fuse 15 direct to the blower. That should work surely, and I figure a damn sight easier to do.

So your getting 12v at the fuse but not in the in the relay connector, so unless there’s an issue with the relay socket the best option is to install an ‘overlay, so taking the existing wire as faulty… leave it there, and run in a replacement wire from relay to the fuse.
Even though the wire has to run behind behind the dash from fuse box to passenger footwell, its easy to do with something flexible such as a long cable tie, and label the wire, someone may wonder what it for.

i had to install an overlay when one of the circuits failed from my discos immobiliser, I didn’t even bother to go there, just pick up an ignition switched supply and run the wire into the engine bay. Simples

Sorry but I couldn’t follow the above, but my blower didn't work on my 96 (which has aircon) and it was the dash slider switch at fault. I managed to clean it up (contacts were burnt) and it works ok now albeit it has sometimes has to be wiggled a bit to get the blower going.

Had a few attempts again over the last week or so. Still no joy. I feel like the only choice is to do an overlay as Discool suggested but I am so against doing that because I refuse to believe its a snapped wire somewhere and I just hate not knowing what it is. If I can understand it a little better then maybe I have a chance, I just dont want to give up just yet.
So what does the blue/red wire coming out of the relay do? When powered it all works fine, but is it supposed to be powered. I think I am staring at the wiring diagram too much but it looks like it should be earthed? So in that case I dont want to run a live wire to it.
Also if its ok to do that why bother taking a wire from the dash (if i went down that route), why not just go straight from the live part of the relay (red wire) right back into the blue and red terminal (with a fuse of course). Its the shortest route to get power to blue and red.

Do appreciate the insight so far. I would just like to learn a lot more before settling on a solution.

Just wanted to add a resolve to this.
I did finally get it working. After tracing back where the blue/red wire gets its power from its the Ignition Load Relay. And checking that the power is going to that from the driver fusebox (satellite 1). I had to conclude that the relay itself may be damaged especially since it is located at the back of the footwell (towards the bulkhead) which is very leaky in my motor (the next job I will be working on). I swapped out the relay and success. All settings work on the blower now without issue.

If I'd have had a better understanding of it from the start I would have found it quicker because its something like number 4 or 5 thing to check going from the battery and underbonnet fuses to inside the cab. Instead where I went wrong was thinking the motor itself may have blown, or something with the resitor pack, or motor relay etc. All of which requried a great deal of glovebox removal to get at. So my suggestion for anyone in the future is to get a good understanding of the wiring diagram and the location of all components and the direction in which the circuit is taking you. Then start to test/replace components along the line from the battery. The reason I thought the ignition relay would not be culprit is because I rather stupidly got confised by the name of it. "That cant be it because If thats not working then how come the car starts? And all other things work" which is not the right way to think about that relay because it does not control the ignition or starter, just shuts off power to everything while the car starts (If I am reading into it correctly).

Just got to put 65% of the dashboard back together now


Oh and thank you to everyone who replied. Piece by piece I learned the system and it was in part due to people posting about it (here or in other "heater blower issue" threads). Without this the journey would be more difficult.

Well done! Its the first time I’ve e seen the ignition load relay mentioned as giving problems.

The ignition load relay does its part by supplying a 12v from the engine bay fuse box via the satellite fuse 6, then onward on a brown/green wire to the relay pin 30 and with the relay operated out to on pin 87 white/green wire which along the way joins the blue/red, and into the blower relay at pin 86.

The circuit is nicely laid out in my Haynes manual