Top 20 1991 GMC Sierra - Page 6 Questions & Answers

Disconnect the negative battery cable.

Disconnect the blower motor lead connector from the wiring harness connector.

Remove the blower motor cooling tube from the blower motor.

Remove the four retaining screws.

Turn the motor and the wheel assembly slightly to the right so that the bottom edge of the mounting plate follows the contour of the wheel well splash panel.

Lift up on the blower and remove it from the blower housing.

Installation the new blower motor by reversing the removal steps.

Connect the negative battery cable.

Things to check...
Check radiator fluid level. Open when COLD. System under pressure when hot. Top up if low.
You need to check the radiator not just the overflow bottle.

If it's already full, then check the heater hose shut off valve. Usually vacuum controlled, against the fire wall. Follow the small hoses back. With engine running, turn the heat control to On or Off and watch for valve to move, may take 30 seconds to move. Fan will not affect this, leave it at low but not off.
If that works OK then check that the interior heat doors / blender are moving when you control the heat.

Was it sudden or come on slowly?
Others may help here too..

check and replace switch on brake padel

your wheel bearings are gone

stick your head way up under the dashboard with a good flashlight. you will see a shaft operated by the brake pedal. follow that shaft to the firewall, all will be revealed.

Hello: Open the tailgate, on the inside of the tail light lens (toward the other tail light) you will find two screws, remove the screws, wiggle the tail light lens assembly and it should come off.

First check the fuse. Second using a multimeter check the blower motor.

there is a short somewhere.i had that problem.there were some wires melted together. I’m happy to help further over the phone at https://www.6ya.com/expert/kenneth_3efc1f8510674f04

It sounds like your Starter solenoid is stuck, worn out, etc. Either way, have your Starter tested at Autozone, or similar, and replace if it is found to be bad. I’m happy to help further over the phone at https://www.6ya.com/expert/jeremy_69f3cc28d95bf514

you most likely only have a blown fuse.look under dash for fuse panel, on underside of fuse panel cover,you will find location of tail light fuse. replace it and your lights should work again. thank you for choosing fixya.com

Check the fuses, this is the most common cause in an electrical system. If the fuses are ok try jumping the switch contact by finding the live wire to the switch and shorting it with one of the other wires. Lastly try taking a feed directly to the one of the input wires on the fan unit itself. Be careful that you do not choose the earth wire if there is one.

If it is the factory Delco/GM radio, should work something like this.

Turn the truck on (does'nt have to be running just accesories on), turn the radio power off (turn volume knob all the way left till off, or power button off depending on the radio). I believe there are two buttons on the front next to each other, seek/scan maybe? Press and hold to change the time. One does hours, one does minutes.

You might need to bleed the brake lines. Sounds like unequal pressure in the brake lines.

you have air in the lines or a leak somewhere. tighten all your fittings and start at the pass side rear wheel. get a piece of vacuum hose that will fit on the bleeder and put one end on the bleeder and one end in a cup half full of brake fluid. have someone start the truck and pump the brakes slowly and watch the cup for bubbles. when the bubbles stop go to the next wheel if they dont stop after five minits of pumping you have a leak. i worked for hours on a truck finally finding a very small leak in the hose that goes from the rearend to the line down the frame. some part stores rent or loan vacuum pumps for doing brakes that work great just hook up to the bleeder and turn it on making sure that the master cylinder stays full and it pulls the fluid thru removing all the air.

is it in front of trans oround the flywheel if is its a freeze plug

http://cgi.ebay.com/ebaymotors/Used-1991-GMC-Sierra-Truck-Service-Shop-Repair-Manual-/130460028224?pt=Motors_Manuals_Literature&hash=item1e60060d40

Sounds like a warm/cold air door motor not working, this is located under the dash in the duct work check that.

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Hi, this is a tough situation, as your brake lines run near the fuel liines, and you do not want to disturb them. The fuel lines are probably discontinued by the dealer. This is ok, because you can use brake lines. This is a low pressure fuel injection (14 psi), so you can safely repair this.The lines use o-rings, and are specially flared. Most auto parts stores have replacement repair lines, with the correct flared ends that you need. In conjunction with brake lines of the same size, and the correct unions, these lines can be repaired rather easily. If it is the line going to the pump above the tank, you may want to consider removing th pick up box, rather than taking the tank out, (risking breaking other lines). As this is a slightly tougher procedure than normal, do this only if you are comfortable with your mechanical ability. Consult your parts store first, to see what is available. Best of luck...Coop

If the Blower is staying on high maximum blow then it is probably the a/c blower relay. The other thing it could be if not on maximum is the blower motor resistor pack. Lastly would be the blower switch shorted to power.

it is in the dash i have the same problem with my heat gage