My heating/ac blower only operated at the high speed so I assumed it was the resistor pack that had failed. I bought a used one online and after installing it, all the blower speeds worked correctly. After a about a week of working correctly I hit the 'auto' button and the blower stopped. While cycling through the fan speeds, high speed was the only one that operated. Does anyone believe that there is something that is killing my resistor packs or do you think that the used one I bought was at the end of its life span?

Thanks for your help.

 

Do you mean power transistor? It allows you to have more than 3 speeds. If fan current was higher than normal it could lead to early failure. Semi-conductors can fail open or closed, they are not always like a fuse.

Speaking of fuses, F7 under the dash is 30 amp and runs the blower. If you measured amps there, and found them to be closer to 30 than 20, might also be an issue with fan motor starting to fail shorted. Motor is expensive, but cheap from dismantler or salvage yard.

 

Does your fan make a lot of noise when it does run? If so it might be full of junk it sucked in causing it to work harder and causing your power transistor to fail. I think this is what happened to mine as when I popped out the fan it was FULL...and I mean FULL.

 

The power transistor is probably heat sinked?
Is there that white heat sink compound between the transistor and the heatsink?
Sometime that goes away.
I have not seen the part.. But, my guess.

Same kind of thermal grease used to keep a CPU heatsink onto a CPU and allow the CPU not to burn up or toast itself.

 

A good point jfall, Rover (Lucas) seems to like free air mounted transistors in some applications. So the main one in the MFU timer module for a D1 is rated for 55 watts on a good heat sink. 1 watt in free air. Mine melted a little hole in the side of the MFU, I replaced interior lights with LEDs to drop the power drain and watts. And a fan full of fluff will draw more amps, so might be right at the edge of what the unit can handle. Exam of the fan is a good idea, plus any pollen filter.

 

This is what I bought used off of ebay.
Resistor - Climate Control Blower Motor (Genuine Part # JGN100010) - Land Rover connector\relays\flasher from Atlantic British

After the reistor was installed, all the blower speeds started working correctly but stopped only after about a week and only the high speed worked.

My blower does squeak sometimes so I will pull it out to check to make sure it is clear of debris and not being overworked. I will also break out my meter and check the fuse box.

 

I'd check the amp load on the motor just to make sure nothing is totally out of whack but, I honestly don't see it killing a resistor in that short of order.

 

now that I am on the right page of the RAVE, the resistor pack does have an internal 40 amp fuse, so maybe fan is drawing too much..... see attached, you can read for the fuse with a meter between green and black/orange wires.