Defender Heater Blower Motor Replacement

2 years 2 months ago - 2 years 2 months ago #9854 by Javelinadave
My heater blower motor never worked and it was time to tackle this issue. The fuse was good and when I tested if there was power I was reading 12 volts so it had to be the motor. I took off the wing top air intake and tried to move the squirrel cage with my hands. It did move but with some resistance. I also found probably half a cup or more of rust flakes, mud and misc crap in the ducting.
I have a LHD truck so if you have a RHD there are a few things you will need to do differently.
First off was liberating the blower motor. I had to move the following out of the way of my 300Tdi powered truck:
Air cleaner
Washer fluid tank
Coolant tank
Fuel filter
I didn't disconnect anything but I moved them out of the way. I then removed two screws that held the ducting in place and slid it towards the front of the fender.
The heater box is held in place by 4 bolts. Two at the top (with captive nuts) and two at the bottom (Held by nuts inside the truck cab). Once you remove those you can pull the heater box away from the bulkhead and have good access to the blower.
Using an 8mm socket you need to remove 5 or 6 nuts and the old blower motor should come free. In my case I couldn't remove the old squirrel cage blower so I had to go with new.
I went to AutoZone and bought this:
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I elected to buy both blowers to combine the parts. The PM137 has two wires like the factory motor but squirrel cage is way to big for the LR housing. The PM136 is a one wire motor (The housing is the ground) but it comes with the correct size squirrel cage blower. Combined they were about $60 so I bought both and moved the smaller cage to the 2 wire motor. The 246 box is the correct pigtail for the 2 wire motor. I cut the wire off the old motor and after checking the polarity I made this little harness.
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If you have a RHD truck you will need to use your old squirrel cage and wire the motor so it spins backwards compared to a LHD truck.

Next up you need to attach the motor to the housing. After many attempts to match up the holes I determined I could only get two to almost match and I had to drill a few new holes for the housing studs to hold things in place. After I bolted them together I sealed up a few tiny gaps with RTV.
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I have an A/C system so putting the bottom bolts back in was a PITA. Instead of using nuts and washers I drilled out the lower holes a bit bigger and installed two riv-nuts for an easier reinstall.

As for the end product it was worth the effort. The fan blows better than any Defender fan I have had in the past. It only runs on high but that could be a bad resistor or it is just the way it is.
I hope this helps somebody and please pay it forward. If you do a project, please do a write-up.

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2 years 2 months ago #9856 by koly
Nice write-up!

00 G500

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