1976 CJ7 Blower Motor Upgrade - Done... - JeepForum.com
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post #1 of 4 Old 02-07-2009, 01:58 PM Thread Starter
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1976 CJ7 Blower Motor Upgrade - Done...

Ok. Thanks to everyone for their help with the blower motor. Because the year model has a different heater setup than the 1977 (some) and higher, I felt I would give a little back to everyone who is going to try this upgrade....


I decided to replace the heater core as well as upgrade the blower motor while I was doing it. There are a few screws in the firewall to remove to get the air box out and you have to remove the two hoses. Once that is done, you need to go into the cab.

There is another screw to the left of the vent (the one right above the stick shift. Remove that. Then remove both cables from the box. Once that is done, you can work the box out. It is somewhat tight but you can keep moving it around and it will come out the passenger side.

Once the box is out, there are screws all the way around the back side of the box (where the two tubes from the core stick out). Take all these off as well as one right next to the tubes. Slide the cover up and off at this point.

Just replace the core at this point and clean out the garbage that maybe trapped in there. Mine had leaves stuffed in there.

Now just go and put all that back together the same way you took it off.

Now to change the blower motor. On these units you will use a different blower motor than the people who have 1977 (some) and newer jeeps. On the jeep that has the blower motor coming out the cab it will turn the opposite way. You will need the Siemens PM123 motor. It comes with the fan already on it.

Now take off the metal that holds the motor. There are something like six bolts that hold it on there. Once it is taken off, then unscrew the small nut on the motor that holds the fan and also unscrew the bolts that hold the motor to the metal.

Once that is done, you will need to cut this metal plate to fit the new motor. I used metal cutters. I cut it the same size as the indention that is on the metal plate.

After you are done cutting, take the new motor (Siemens PM123) and take off the fan (same nut that you had on your original motor). Then slide the fan up and off. Place the new motor on the metal plate. I used short #8 metal screws to secure the motor to the metal plate.

Now that that is done, you should test the fan. There is a positive and ground that comes out of the motor. Secure the ground and then (with a fuse in the line) hook up the motor to a positive source. If the motor turns, you are on the right track. (I found that my ground wasn't good and the motor wouldn't turn and that gave me 15 minutes of soul searching).

After making sure the motor is working, reattach the motor which is secured to the metal plate back to the housing.

Go through the opposite steps to reattach the housing to the jeep. After that is done. I used a simple on/off switch from Home Depot. Up is on and down is off. It had two wires already on it.

I ran the positive wire to this switch and from the switch to the power source. I attached the ground to a ground post.

The fan hums and everything should work at this point.

NOTE: If you are not changing the heating core on your jeep, there is no reason to go into the motor area. You can remove just the six or so screws on the plate that holds the motor and slide it out. That is VERY easy to do and saves alot of time. Just follow the steps above to mount the new motor.

In another post of mine trying to figure this out, people suggested buying resistors that you can change the speed of the fan. I may do this at a later date but am not very good with electricity and am happy to get this done right now.

Anyway....I hope this helps anyone who wants to upgrade to the larger blower motor on their 1976 and earlier Jeeps that have the blower motor sticking out into the cabin.

Thanks for everyone's help on my earlier post.

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post #2 of 4 Old 02-07-2009, 02:31 PM
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Pics. Post pics.

"In the end...It's all Hack."
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post #3 of 4 Old 02-07-2009, 04:07 PM Thread Starter
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Here are some pictures of blower motor upgrade....

Unfortunately, I did not take them as I was going through the process. I was flying by the seat of my pants and I was concerned with the install at the time. I wish I had thought about that.

The first picture is a picture of one of the screws that hold the air box to the frame. You have to go into the motor compartment to access this screw and the other one that is located under the battery tray.


This picture is the metal screw that holds the motor to the metal plate that is attached to the air box. I put three of these screws in to hold the motor against the air box.


This picture is the actual motor and the wires. You will notice the two wires (Red and Black). The red one is the positive and the black is the ground. This motor can be picked up for $39.99 +/- at any auto parts store.


Finally, this is a picture of the switch that I used to control the fan. It is a simple on/off switch that I purchased from Home Depot.


I hope these pictures and write up help with someone attempting to do this install.
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post #4 of 4 Old 07-31-2015, 06:37 AM
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1976 Heater Blower R&R

Hi, Well, here we are, 8 years later, and I'm going through the same path as you with my 1976 CJ-7 (interior facing blower motor/unit)! Sadly, the photos you posted way back then to Photobucket are gone now. Any chance you could re-post? I intend to use the original 2-speed switch (the one with the resistors that create the 2-speeds) which should be a direct pigtail tie in. How well and how long did your fix work?
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