GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1998 🢒 Jimmy - 2WD 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 Cooling Insufficient - Air Conditioning (A/C) Inoperative

The compressor is a scroll compressor that matches the air conditioning demand by changing the compressor stroke, instead of cycling the compressor clutch. A capacity control valve located in the compressor senses the low side pressure and causes the compressor to adjust to A/C cooling demands. The compressor always runs and the system does not cycle. However, the compressor may cycle if the cooling load is not reduced enough by the capacity control valve.

Preliminary Checks
    • Inspect the proper operation of the cooling fans.
    • Inspect for system voltage above 10.5 volts.
    • Inspect the A/C fuse. Replace as necessary.
    • Inspect the A/C blower operation. Repair as necessary.
    • Inspect the clutch coil electrical connection. Repair as necessary.
    • Inspect the drive belt. Replace if damaged or missing.
    • Inspect the condenser for restricted air flow. Clean as necessary.

Refer to the following tables when you are diagnosing insufficient cooling complaints.

Step

Action

Value(s)

Yes

No

1

Did you perform the Functional Check?

--

Go to Step 2

Go to Functional Check

2

Inspect for any stored DTCs.

Are any DTCs stored?

--

Go to Step 4

Go to Step 3

3

Connect the J 39500-B .

Are the pressures above 350 kPa (50 psi)?

--

Go to Step 5

Go to Step 9

4

Correct any stored DTCs.

Does the complaint persist?

--

Go to Step 3

Go to Functional Check

5

Inspect and correct for a blown Air Conditioner (A/C) fuse.

Does the complaint persist?

--

Go to Step 6

Go to Functional Check

6
  1. Disconnect the A/C clutch connector.
  2. Inspect the A/C clutch for proper rotation.

Refer to does the A/C clutch rotate smoothly?

--

Go to Step 7

Go to Functional Check

7

Inspect and correct for the following conditions:

    • Proper operation of the cooling fans.
    • Condenser restrictions
    • Radiator restrictions

Does the complaint persist?

--

Go to Step 8

Go to Functional Check

8
  1. Read the DCS for Bulletins and Hints.
  2. Follow the procedures indicated.

Does the complaint persist?

--

Go to Step 11

Go to Functional Check

9
  1. Add 0.453 kg (1 lb) of refrigerant.
  2. Perform a leak check. Refer to Leak Testing

Did you find a leak?

--

Go to Step 10

Go to Step 11

10
  1. Repair the leak.
  2. Inspect the system performance. Refer to System Performance Test .

Does the complaint persist?

--

Go to Step 3

Go to Functional Check

11

Perform an A/C Performance Check using the following steps:

  1. Ensure that the ambient temperature is at least 6°C (43°F).
  2. Ensure that the engine is idling at normal operating temperature.
  3. Turn the A/C to the ON position.
  4. Select the coldest setting.
  5. Select the MAX blower speed.
  6. Record the A/C pressures.
  7. Record the A/C temperatures.
  8. Refer to System Performance Test .

Does the A/C performance meet the requirement on the Performance Chart?

--

Go to Step 12

Go to HVAC High Side vs. Low Side Pressure Table

12

Was the customer complaint made due to high temperature and/or high humidity?

--

Go to Functional Check

Go to Step 13

13

Perform a leak test. Refer to Leak Testing

Did you find a leak?

--

Go to Step 14

Go to Functional Check

14

Evacuate and recharge the A/C system. Refer to Refrigerant Recovery and Recharging .

Is the repair complete?

--

Go to Functional Check

--