GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1998 🢒 Jimmy - 2WD 🢒 HVAC 🢒 Heating, Ventilation and Air Conditioning 🢒 Blower Motor Inoperative at Any Speed

Step

Action

Value(s)

Yes

No

1

Was the Heater Blower Controls System Check performed?

--

Go to Step 2

Go to Heater Blower Controls System Check

2

Inspect the HVAC fuse (fuse 9).

Is the HVAC fuse open?

--

Go to Step 3

Go to Step 4

3
  1. Locate and repair the short to ground in one or more of the following circuits:
    2. • CKT 141
    • CKT 64
    • CKT 63
    • CKT 72
    • CKT 52
  2. Replace the fuse.

Is the repair complete?

--

Go to Heater Blower Controls System Check

--

4
  1. Turn on the heater control mode switch to any position.
  2. Turn the blower switch to one of the following positions:
    3. • LOW
    • MED-1
    • MED-2
  3. Disconnect the blower motor relay.
  4. Turn the ignition switch to the RUN position.
  5. Use a J 39200 Digital Multimeter (DMM) in order to measure the voltage between the blower motor relay connector cavity 87A and ground.

Does the J 39200 DMM display battery voltage?

--

Go to Step 5

Go to Step 12

5

Connect a fused jumper wire between the blower motor relay cavity 87A and cavity 30.

Does the blower motor operate?

--

Go to Step 6

Go to Step 7

6

Replace the blower motor relay. Refer to Blower Motor Resistor Replacement .

Is the repair complete?

--

Go to Heater Blower Controls System Check

--

7
  1. Reconnect the blower motor relay.
  2. Disconnect the blower motor connector.
  3. Using the J 35616-A , construct jumper leads in order to connect blower motor terminal A to connector terminal A.
  4. Turn the ignition switch to the ON position.
  5. Turn the blower switch to the HIGH position.
  6. Use a J 39200 DMM in order to measure the voltage between the blower motor CKT 65 (PPL) cavity A and battery ground.

Does the J 39200 display battery voltage?

--

Go to Step 9

Go to Step 8

8

Locate and repair the open in CKT 65 (PPL) between the blower motor and the blower motor relay.

Is the repair complete?

--

Go to Heater Blower Controls System Check

--

9
  1. Reconnect the blower motor relay.
  2. Disconnect the blower motor connector.
  3. Using the J 35616-A , construct jumper leads in order to connect blower motor terminal A to connector terminal A and blower motor terminal B to connector terminal B.
  4. Turn the ignition switch to the ON position.
  5. Turn the blower switch to the HIGH position.
  6. Use a J 39200 DMM in order to measure the voltage between the blower motor terminal A (CKT 65) and blower motor terminal B (CKT 850).

Does the J 39200 DMM display battery voltage?

--

Go to Step 10

Go to Step 11

10

Replace the blower motor. Refer to Blower Motor and Fan Replacement .

Is the repair complete?

--

Go to Heater Blower Controls System Check

--

11

Locate and repair the open in CKT 850 (BLK) between the blower motor and G117.

Is the repair complete?

--

Go to Heater Blower Controls System Check

--

12
  1. Use a J 39200 DMM in order to backprobe the heater controller connector C2 cavity C to ground.
  2. Measure the voltage.

Does the J 39200 DMM display battery voltage?

--

Go to Step 14

Go to Step 13

13

Locate and repair the open in CKT 141 (BLK) between the heater controller and the IP fuse block.

Is the repair complete?

--

Go to Heater Blower Controls System Check

--

14
  1. Use a J 39200 DMM in order to backprobe the heater controller connector C2 cavity B to ground.
  2. Measure the voltage.

Does the J 39200 DMM display battery voltage?

--

Go to Step 15

Go to Step 16

15

Locate and repair the open in CKT 64 (BRN) between the heater controller cavity E connector C4 and cavity B connector C2 and connector C203, cavity C6.

Is the repair complete?

--

Go to Heater Blower Controls System Check

--

16

Replace the heater controller. Refer to Control Assembly Replacement .

Is the repair complete?

--

Go to Heater Blower Controls System Check

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