Blower motor does not work on any speed, ac light does not come on when depressed

check and test fuses -relays for a/c system

Check the AC fan relay
Symptoms Of A Defective Blower Motor Relay
The blower motor relay's job is to basically bypass the current that passes thru' blower motor resistor and deliver it directly to the blower motor. With the blower motor getting full battery current, it'll run in HI speed.

The most common symptom you'll see, when the blower motor relay fails in your Chevy S10 (GMC S15), is that the blower motor will not run in HI speed (but will run in LO, M1, and M2 speeds).

In some cases, the blower motor will fail and the blower motor will not run in HI but you'll have all of the other speeds working.

https://easyautodiagnostics.com/gm/2.8L/blower-motor-relay-multimeter-test-1

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Could be a number of thing's ! Testing the electrical circuit is the way to find out what's wrong . Using a wiring diagram and a DVOM - digital volt ohm meter . Videos on youtube showing how to test it ! Without testing i would only be guessing . Does it work in high speed ? In high speed it by-passes the resistor . If it doesn't work in any speed more then likely the blower motor is the problem !
Air Speed
The HVAC control assembly applies ground to the blower motor control circuit that corresponds to the selected blower speed. The resistors and the blower motor are in a series circuit. The following list represents the number of resistors in series with the blower motor per particular speed request:
• Low speed--3 resistors
• Medium 1 speed--2 resistors
• Medium 2 speed--1 resistor
When the operator requests High speed, the HVAC control assembly applies ground directly to the blower motor through the high blower motor control circuit. The resistor card has a fusible link which, if blown, will require that the card be replaced.

Blower Motor and Resistor Diagnostics by Wells

Likely the blower motor resistor. located right next to the blower motor, this device is resposible for reducing the voltage suplied to the motor. when it fails you may loose some or all speeds of the motor

I’m happy to assist further over the phone at https://www.6ya.com/expert/samuel_dda9c48bb7ffbfd3

Check this procedure...Blower Motor Resistor and Controller Replacement


REMOVAL

1. Disconnect and isolate the batten' negative cable.

2. Depress locking tab and unplug the wire harness connector from the blower motor

resistor or controller (power module).

3. Depress locking tab and unplug the resistor or controller connector from the blower

motor.

4. Remove the 2 screws that secure the blower motor resistor or controller to the

heater-AC housing.

5. Remove the blower motor resistor or controller from the heater AC housing.


INSTALLATION

1. Install the blower motor resistor or controller to the heater AC housing. The

housing is indexed to allow (controller power module) mounting in only one

position. Tighten the mounting screws to 2.2 Nm(20 in. Lbs.).

2. Plug in the wire harness connector to the blower motor resistor or controller.

3. Plug in the connector from the blower motor resistor or controller to the blower

motor.

4. Connect the batten' negative cable.




Hope this helps (rerember to rating this and leave a testiomonial).

Does it work in any speed?? If low speeds are in-op but you have high speed resistor is bad ,,if you nothing then i would look for a relay bad..

Welcome to FIxYa.com

Blower Motor Resistor and Controller Replacement

Image Blower Motor Resistor Or Controller/Power Module Remove/Install

REMOVAL

1. Disconnect and isolate the batten' negative cable.

2. Depress locking tab and unplug the wire harness connector from the blower motor

resistor or controller (power module).

3. Depress locking tab and unplug the resistor or controller connector from the blower

motor.

4. Remove the 2 screws that secure the blower motor resistor or controller to the

heater-AC housing.

5. Remove the blower motor resistor or controller from the heater AC housing.

INSTALLATION

1. Install the blower motor resistor or controller to the heater AC housing. The

housing is indexed to allow (controller power module) mounting in only one

position. Tighten the mounting screws to 2.2 Nm(20 in. Lbs.).

2. Plug in the wire harness connector to the blower motor resistor or controller.

3. Plug in the connector from the blower motor resistor or controller to the blower

motor.

4. Connect the batten' negative cable.

Thank you for using FixYa.com

Regards, Lee Davidian

replace the blower motor resistor. It controls the fan speeds. It defaults to high speed only when it fails.

How to replace the blower motor resistor block: Caution: Stay clear of the blower motor and resistor block (Hot). Do not operate the blower motor with the resistor block removed. 1. Disconnect and isolate the battery negative cable.
2. Remove the glove box from the instrument panel.
3. Pull out the lock on the blower motor resistor wire harness connector to unlock the connector latch.
4. Depress the latch on the blower motor resistor wire harness connector and disconnect the connector from the resistor.
5. Remove the two screws that secure the blower motor resistor block to the HVAC housing.
6. Remove the resistor block from the HVAC housing. Installation:
1. Position the blower motor resistor block into the HVAC housing.
2. Install the two screws that secure the resistor block to the HVAC housing. Tighten the screws to 2.2 Nm (20 in. lbs.)
3. Connect the wire harness connector to the resistor block.
4. Push in the lock on the blower motor resistor wire harness connecgtor to lock the connector latch.
5. Install the glove box.
6. Reconnect the battery negative cable.
7. Have a nice day!

Your blower speed resistor has gone bad and needs to be replaced. You can pick one up at Auto Zone or Parts Source with the step by step instructions to getting the resistor replaced with common tools.

It is located under the glove box, way in the back of the passenger foot area. You'll need to remove 2 screws with a 7mm socket, and remove the plastic cover that covers the blower motor and another component box that I think controls the passenger airbag. After removing the plastic cover you'll need to side that passenger airbag module to the right so it pop off its mounting bracket and move it out of the way. That will give a better view of the blower motor. I highly recommend you also remove the blower motor itself because the Blower Motor Resistor is located behind it. I think you'll need a 5mm or 5.5mm socket to remove the 3 screws that hold in place the blower motor and 2 more screws for the Blower Motor Resistor... It's a cramped location to work in but if you have all the tools and enough lighting then it shouldn't take more than 30-60 minutes to do. The Blower Motor Resistor costs about $19-$25. Good luck

It's either your fuse, blower motor or the switch. More than likely the blower motor. You'll have to take it out and get a new one. Use a test light to see if there is power at the motor when the key is on and the fan switch is on. If power is present, then your motor is gone.