Discovery 300Tdi heater blower doesn't work

Hello everyone,

My Disco 1 300Tdi heater blower doesn't work. I've read quite a few helpful threads and checked lots of things in vehicle but I am now stuck. Could anyone help please?

Here's what I've checked so far.

1 - Blower motor removed and works ok with a direct 12v feed to the terminals.

2 - Fuses ok. In main fuse box and in-line fuse near to blower itself.

3 - Ignition load relay K127 in RHS footwell works ok all terminals show correct voltages and I can here it click on ignition.

4 - I replaced the slider switch. Now I can see voltages in circuit after the switch ok for positions 0, 1, 2, 3 and 4.

5 - Resistor pack seems ok. I can read voltages ok after resistor in all slider switch positions. Even when I remove the resistor pack, the fan still doesn't run on position 4 (which it should).

6 - Recirculation button and flap works ok.

7 - Blower motor relay seems ok. It is energises on ignition 2, and output (White/red) is 0v at switch pos 0 (correct) and +11.4v at all other slider switch positions. Just to check, does anyone know exactly what voltage I should see on each wire at IGN2? I have Red, White/Red, White/black, thin brown and thin blue/red.

It could be a bad earth from this relay, but I'm not an electrician. Is the thin brown wire the earth? At IGN2 it shows +11v in all slider switch positions. Is this correct or should it show 0v as earth? How do I test it for earth?

Where is the earth located from this relay? Is there a physical nut and bolt on the body somewhere or is it just a wire within the loom?

8 - My air con switch doesn't light up and I can't hear anything click. Could that be the same or a different fault?

Sorry for the lengthy post but I thought I'd get it all down at the start.

Thanks in advance to anyone that can help!

have you tried for continuity along all the cable's ?

Not every wire, but quite a few! There are two wires into the blower itself. White/red from the blower relay which reads +11.4v, and a black/orange wire from the resistor pack which also reads +11.4v. Is this correct?

I'm keen to find if the earth from the relay is bad but I don't know how to check that. Any ideas?

I have this issue. Haven't got round to looking into it yet. On a few occasions while off road, it came back on for a few minutes but most of the time the blowers don't work. How easy is it to get to the wiring?

Getting at the wiring depends on where the fault lies. The blower itself, blower relay and resistor pack are all under the LHS footwell and easily accessible. For better access, remove the cardboard kick panel and the glove box (4 screws). It's a bit fiddly but once you've identified those parts you can use a multimeter to check the individual wires.

The ignition load relay K127 (the 12v feed for the slider switch and other things) is behind the vertical panel next to your right foot in the right seat. You have to take off the flat black trim by the door first (4/5 screws) and then the vertical colour trim, but it's not difficult. It is one of 3 or 4 relays behind there. On my car it is the yellow one furthest from the door.

The hardest thing to get at is the slider switch. You have to take out quite a few screws to get the dashboard facia off, then the heater control facing with 3 dials. Then you can reach the slider switch wires. If you need to replace the switch be careful. It doesn't come out easily and the plastic surround breaks if you force it. Just take your time and be patient.

My tip - As always, keep all your screws safe! There are so many different types it's easy to mix them up. Sellotape them to some paper and make a note of where they come from as you go.

Justin Whiting said:

Getting at the wiring depends on where the fault lies. The blower itself, blower relay and resistor pack are all under the LHS footwell and easily accessible. For better access, remove the cardboard kick panel and the glove box (4 screws). It's a bit fiddly but once you've identified those parts you can use a multimeter to check the individual wires.

The ignition load relay K127 (the 12v feed for the slider switch and other things) is behind the vertical panel next to your right foot in the right seat. You have to take off the flat black trim by the door first (4/5 screws) and then the vertical colour trim, but it's not difficult. It is one of 3 or 4 relays behind there. On my car it is the yellow one furthest from the door.

The hardest thing to get at is the slider switch. You have to take out quite a few screws to get the dashboard facia off, then the heater control facing with 3 dials. Then you can reach the slider switch wires. If you need to replace the switch be careful. It doesn't come out easily and the plastic surround breaks if you force it. Just take your time and be patient.

My tip - As always, keep all your screws safe! There are so many different types it's easy to mix them up. Sellotape them to some paper and make a note of where they come from as you go.

Click to expand...

Wow I am lucky if i remember where i put the box with the screws in if i remember to put them in a box lol

I managed to fix it and the blower and aircon now work ok on all settings. HOORAY!

I finally got the wiring diagram and found the slider switch earth wire was an open circuit. The culprit was a faulty slider switch in position 4. A dodgy connection within the switch itself must have lead to overheating and a blown earth wire.

I already had a new slider switch, so fitted that. I replaced the earth wire and used a ring connector at the other end clamped on the earth post under the dash near your left foot in the left seat.

What a great feeling when something stumps you for ages and you finally fix it. I'm very pleased with myself!

Hi Justin,
Thank you for your post above, I have just discovered the same problem with my 300TDI,
only the blower is not working, the air con switch works and you can hear the a/c compressor
engagement, only need to ask you about faulty slider switch in position 4.
Do you mean the switch which sides to regulate the speed of the blower ?
If so how do you take the switch out please?
Thanks
Eric

Don’t hold your breath Justin hasn’t been seen since Nov 2012

Position 4 is a direct feed therefore bypassing the speed resistors that are on the side of the heater box. So pull the two round heat controls/ direction control knobs and the knob of the slider and u will find a couple screws, undo and remove the plate, remove and remove more screws and the plastic back to access the switch, 5 mins max.

Lots of info in the Forum already and on the www with pictures.

Try this link http://www.landy.ee/manuals/electricity/Disco_Elec.Troubleshooting Manual - LRL0077ENG (1997).pdf


And this one http://www.landroverresource.com/docs/D1_Workshop_Manual.pdf

Sent from my iPad on a train