GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2000 🢒 DeVille 🢒 HVAC 🢒 Heating, Ventilation and Air Conditioning 🢒 VDOT Air Conditioning (A/C) System Diagnosis

Step

Action

Yes

No

1

Did you perform the System Performance Test?

Go to Step 2

Go to System Performance Test

2

Are the high and low pressures above normal according to the performance chart readings?

Go to Step 11

Go to Step 3

3

When performing the system performance test, compared to the performance chart, inspect for the following:

    • Low side pressure normal
    • High side pressure out of normal range
    • Left center discharge temperature above normal

Do the listed conditions exist?

Go to Step 4

Go to Step 5

4
  1. Perform a leak test on the system. Refer to Leak Testing .
  2. Recover the refrigerant from the A/C system. Refer to Refrigerant Recovery and Recharging .
  3. Repair the leak if found and recharge.

Did you complete the repair(s)?

Go to Step 18

--

5

When performing the system performance test, did the high and low side pressures remain equal and not change while the compressor was running?

Go to Step 7

Go to Step 6

6

When performing the system performance test, compared to the performance chart, inspect for the following:

    • The compressor noisy
    • Low side pressure above normal range
    • High side pressure below normal range
    • Discharge temperature warm

Do the listed conditions exist?

Go to Step 8

Go to Step 9

7
  1. Inspect for a missing or damaged orifice tube. Refer to Expansion (Orifice) Tube Replacement .
  2. Inspect for a blockage in the high side refrigerant lines.
  3. Repair as necessary.

Did you find and correct the condition?

Go to Step 18

Go to Step 8

8

Replace the A/C compressor. Refer to Air Conditioning Compressor Replacement .

Did you complete the repair?

Go to Step 18

--

9

When performing the system performance test, did the compressor clutch cycle ON/OFF rapidly and cause compressor noise?

Go to Step 10

Go to Step 12

10
  1. Inspect for an undercharged A/C system.
  2. Recover and recharge the refrigerant. Refer to Refrigerant Recovery and Recharging .

Did you find and correct the condition?

Go to Step 18

--

11

Inspect for improperly working cooling fans.

Are the cooling fans operating properly?

Go to Step 12

Go to Electric Cooling Fan Diagnosis in Engine Controls

12

When performing the system performance test, was the liquid line warm downstream of the orifice tube?

Go to Step 13

Go to Step 14

13
  1. Perform a leak test on the system. Refer to Leak Testing .
  2. Recover the refrigerant. Refer to Refrigerant Recovery and Recharging .
  3. Repair the leak if found.
  4. Inspect for a missing or damaged orifice tube/O-ring.
  5. Inspect for system blockages.
  6. Repair the system as necessary and recharge.

Did you complete the repair(s)?

Go to Step 18

--

14

When performing the system performance test, was the liquid line cold upstream of the orifice tube?

Go to Step 15

Go to Step 16

15

Locate the restriction in the high side line and repair.

Did you complete the repair?

Go to Step 18

--

16

Inspect the A/C condenser for blockages, bent or damaged fins causing insufficient air flow.

Did you find and correct the condition?

Go to Step 18

Go to Step 17

17
  1. Inspect for a plugged orifice tube. Refer to Expansion (Orifice) Tube Replacement .
  2. Repair as necessary.

Did you complete the repair?

Go to Step 18

--

18

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Symptoms in HVAC Automatic