Heater Fan Motor Replacement

When I was doing the test drive for my Puch-G I noticed the cabin fan did not work. "No big deal," I thought to myself. - it is probably a fuse or a defective switch. Even if it was the motor, I had replaced cabin motors in my MG-B and Jaguar MKII so how hard could it be?

Some quick troubleshooting with a volt-ohm-multimeter confirmed the switch was getting power, working and it was probably the blower motor. So what if it needed to be replaced, no big deal because I've done it before. I was right... and wrong: replacing the motor is very easy, getting to it, not so much.

My Puch-G is an old Austrian Military G from 1991 and since it was a radio truck, it features a 24v electrical system so when I called Sean at EuroTruck Importers and he said he had a Bosh 24v motor PN 0130007004 in stock I was worried that it would be hard to find later so purchased it for $135.

That Bosh blower motor sat on the shelf for almost two years before I got the nerve to replace it. Asking around about replacing the motor, everyone said it was no big deal, "you just have to pull out the dash." After three days of work, I'm going to tell you not only do you have to pull the ENTIRE dash, trim, glove compartment, gauges, vents, handle, center console, steering wheel, windshield support (my windshield folds down), switches, turn signals, heater ducts, metal dash, and the heater. You see the cabin fan sits in the middle of the firewall between the air-intake and the cabin.

It is not hard work, it just takes a LOT of time. I'm not going to go through the process step by step because the W460 G-Wagons were made for well over a decade and military versions like mine even longer. So dash configurations differ over the years. What I want you to know is that the process is not hard but is time-consuming. Easily done by anyone with medium skill level and simple tools.

As you start pulling the car apart, follow these simple rules:

• Remove the negative connector from your battery prior to doing anything.
• Take photos as you go to document where everything goes.
• Mark the screws and bolts so they go back to the correct place - poking them into cardboard with Sharpie notes works great.
• Don't force anything, most parts come out easy, so if it is not coming out, look for more screws.
• The flexible ducting will easily break, so just order some before you get started.
• While in there, plan to put some Dynamat and Dynaliner on the firewall and on the inside of the dash to quiet things down.
• Blow everything out with compressed air, and do a deep clean before putting it back together, I used dishwashing liquid bath and a clean water rinse.



W460 Dash Removed Showing Heat Exchanger

• Use Deoxit on the electrical connectors.

The photo here is what it should look like after pulling everything out. That dust you see is over 30 years of dirt courtesy of the Austrian military. In the middle is the entire heating and blower unit. You will need to remove the side plenum ducts shown here prior to removing the center unit. There were three Phillips screws on each side. Don't attempt to remove the top plenum as it is difficult to remove and the unit comes out nicely with the top attached.

You can see the flexible side and windscreen ductwork has been removed on the right and the left it still connected. You will need to remove the top dash prior to getting the heater/blower out. There are two small Phillips-head screws in the back holding the top dash in place. Remember to remove the coolant hoses on the right side. Turn off the heat valve and have a small container handy as you will get some coolant spilling into your cabin.

Once out you will need to take the heat exchanger apart to get to the fan motor on the backside. This process is easier if you heat up the box a little with a hairdryer and use some trim tools to pry the tabs out while pulling the back off. Be careful the tabs are brittle and will break.

Once out you will see the fan and in my case the resistor for low-speed operation. My Puch-G only has two speeds later W460 trucks feature a three-speed fan. You can remove the cables by unplugging them from the motor, they are polarized so there is no way to plug them in wrong. Remember to spray the electric connectors with Deoxit.

Remove the two spring clips holding the motor and slip it out toward the back with the fan attached. The fan is very difficult to remove, but it is held in place with only friction, no glue, clips or screws. Be careful with the fan because you will notice some clips on the blades that were put in place to balance the fan; consider using some tape to hold them in place until after you get it installed again.

Clean everything very well. The new motor came with a plastic cover that made me think it would not fit, but the cover just needed to be removed. Also, on the back of my old motor is a small plastic cap covering the rear bearing, I carefully removed it from the old motor and snapped in on the new one. I slid the motor in place, installed the clips that held the motor secure, electrical connectors then finally mounted the fan. Once again the fan held in place on the spindle with friction and don't push it too far in as the fan will scrape against the housing. I tested the fan with a motor prior to putting the heater box back together.

I pulled out the heat exchanger (it looks like a radiator) and blew it with compressed air I also replaced the foam holding the exchanger in place as it was deteriorated. All the plastic pieces got a bath inside and out then I put the heater box back together.

Cleaned and Mounted Heat Exchanger

Then I simply reversed the take apart process carefully following the order; hint: leave the glove box, steering wheel, gauge cluster, and speaker cover for last - even after installing the center console. Here is how the cleaned heating unit looks installed before putting the dash back in. No more Austrian dust!

I also changed the heater valve cable. These are notorious for getting hard to adjust over time and with everything apart super easy to replace and adjust.

While all the parts were out, I took the opportunity to thoroughly clean the dash parts and put some Dynamat on the backside of the metal dash to kill that tin can sound. I also used some rubbing compound to clean up the painted pieces and polished them with car wax. All plastic pieces got a bath before putting them back in as well.

Some of the foam that was between pieces needed replacing so I used some adhesive weather stripping to replace the foam with new. Now the truck has a working fan that blows clean air and my dash looks good as new. Just remember - this project takes TIME. After 2 years of procrastination, my defective motor is finally replaced and the heater blows clean air.