Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Inspection and Verification
- Verify the customer concern by operating the climate control system to duplicate the condition.
- Visually inspect for obvious signs of mechanical or electrical damage.VISUAL INSPECTION CHART
Mechanical Electrical - Loose, missing or damaged A/C compressor drive belt
- Loose or disconnected A/C clutch
- Loose, misrouted or damaged vacuum linesa
- Broken or leaking vacuum control motora
- Discharged A/C system
- Broken or leaking refrigerant lines
- Central junction box (CJB) fuse(s):
- 23 (20A)
- 24 (15A)
- 27 (15A)
- 34 (10A)
- Battery junction box (BJB) fuse(s):
- 2 (40A)
- 17 (10A)
- Blower motor inoperative
- A/C compressor inoperative
- Circuitry open/shorted
- Disconnected, loose fitting or incorrectly installed electrical connectors and pins
a A leak in the vacuum control circuit may occur during acceleration (slow leak), may exist at all times (large leak), and may exist only when specific functions are selected (indicating a leak in that portion of the circuit). The vacuum hoses used in the passenger compartment control circuit are constructed from PVC plastic material. The vacuum hoses used in the engine compartment are constructed of Hytrel®. Because of the materials used, never pinch the vacuum hoses off during diagnosis to locate a leak. A wood golf tee can be used as a plug when it is necessary to plug one end of the vacuum hose for leak test purposes.
- As pinpoint tests and measurements are being performed, be sure to inspect for any disconnected, loose fitting or incorrectly installed component, module and in-line electrical connectors and pins.
- If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
- If the cause is not visually evident, connect the scan tool to the data link connector (DLC).
- If the scan tool does not communicate with the VCM:
- check the VCM connection to the vehicle.
- check the scan tool connection to the VCM.
- refer to MODULE COMMUNICATIONS NETWORK article, No power to the scan tool, to diagnose no communication with the scan tool.
- If the scan tool does not communicate with the vehicle:
- verify the ignition key is in the ON position.
- verify the scan tool operation with a known good vehicle.
- refer to MODULE COMMUNICATIONS NETWORK article to diagnose no response from the powertrain control module (PCM).
- Carry out the network test.
- If the scan tool responds with no communication for one or more modules, refer to MODULE COMMUNICATIONS NETWORK article.
- If the network test passes, retrieve and record continuous memory diagnostic trouble codes (DTCs).
- Clear the continuous DTCs and carry out the self-test diagnostics for the INTRODUCTION -- DIESEL ENGINES or INTRODUCTION -- GASOLINE ENGINES article.
- If the DTCs retrieved are related to the concern, go to INTRODUCTION -- DIESEL ENGINES or INTRODUCTION -- GASOLINE ENGINES article Diagnostic Trouble Code (DTC) Index. For all other DTCs, refer to MULTIFUNCTION ELECTRONIC MODULES article.
- If no DTCs related to the concern are retrieved, go to Symptom Chart .
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.