This 1992 GMC C1500 pickup came in with the complaint that the blower motor was squeaking and the noise was getting worse. The blower motor is located under the passenger side of the dash and has this rubber and foam sound deadening cover over it.
I know it seems strange but the first step in removing the blower motor assembly is to remove the glove box liner. Remove the two plastic pins that hold the door straps to the dash as shown below; one on each side.
Then remove the four 7 mm headed screws that hold the liner to the dash; two on each side.
Pull the upper edge of the glove box liner out and lift it up to clear the hole. It may take a little wiggling.
The silver box is the PCM and underneath it is the foam and rubber cover that has to be removed. There will generally be a fair amount of dust on everything in this corner of the dash. This one also has a good bit of hair from a dog. I used my shop vac to remove the worst of the hair and dust.
In theory the PCM should just slide towards the center of the dash but I have never had much success with that approach. Instead I use a large common screwdriver to lift the PCM up and off of the two securing clips. It does not take mush effort except for remembering the grab the clip before it fall and you have to go looking for it.
With the clips removed the PCM can be positioned to make it easier to remove the harness connectors. Although the PCM is fairly rugged it is best to treat it as delicate as possible. Make sure you depress the latches and pull the harness connectors straight out. Once the harnesses are disconnected, the PCM can be removed from the glove box opening.
There are four 7 mm headed screws that hold the PCM bracket to the blower case. The two on the top have to be fully removed.
The two on the front edge only have to be loosened to remove the bracket.
A better view of where the two top screws are located.
At this point the wires can be disconnected from the blower motor. The ground wire has a latch that has to be depressed. You can also remove the two front screws that held the PCM bracket in place. It makes it slightly easier to remove the cover.
There is one more screw on the top of the cover that has to be removed.
Now the top edge can be lifted up and off of the hooks.
Then wiggle the cover down from the dash. Be careful to not damage the cover.
Now remove the screws form the sill plate (sorry no picture) and then remove the right kick panel cover.
Remove the lower dash securing bolt with a 13 mm head.
Use a pry bar to free the bracket form the pivot pin.
Then pull the corner of the dash away from the blower motor area. The bracket will now be in front of the pivot pin.
Go around the outer edge of the blower motor and remove the mounting screws. Do not remove the grounding tab screw at this point. You will also need to remove the small rubber hose that connects between the side of the blower motor and the tube on the blower case. This hose is very important to the life of the blower motor. Do Not Lose it and DO Remember to install it on the new motor. It uses some of the air from the blower case and directs it into the blower windings to keep the blower motor cool.
Now the blower motor can be rotated around and wiggled from the dash. You may need to hold out on the lower corner of the dash with one hand while removing the motor with the other.
Be sure to clear the blower case and the evaporator fins of all debris before reassembling. I used my shop vac with a small hose attachment.
Note the position of the grounding tab on the old blower motor.
Remove the paint from the area where the grounding tab will be mounted on the new motor.
Install the grounding tab in the same position it was in on the old motor. This is important so that the cover will lay properly in place and so that the ground wire can be reattached easily.
Note the vent hole on the old blower motor.
The new motor may have more than one vent hole. You will need to remove the plug from the hole so that the tube may be installed into it. Make sure that if there are any other vent holes in the motor housing that they are plugged.
Reassemble the blower motor into the dash and install all removed parts. The top two screws that are in recesses in the PCM mounting plate cane be difficult to start. I sue a little trim adhesive on the screw head to hold the screw into a socket. This makes it easier to install. Also remember to install the two screws in the front edge of the bracket, back onto the blower case, before the bracket is installed. That way all you have to do is tighten them up. Much easier than trying to install them with everything back in place.
While you are there make sure there is no sign of discoloration on the large red wires in the inline harness connectors. This one is for the blower power supply.
This one is a major power supply for the ignition switch, if I remember correctly.
Inspect both sides of the connectors. There is no need to disconnect them. Just look for discoloration of the red insulation. If it is discolored, cut the wire on both sides of the connector and splice the two wires back together with the appropriate terminal.
Make sure you take the time to properly install all of the removed parts. Now the blower motor will work with minimal noise.