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.
Diagnostic Aids
Consider branch circuits and splices to other components. If complaint is insufficient cooling, problem may be an inoperative cooling fan. See CHART C-12 for cooling fan diagnosis. If fan operates correctly, ensure A/C system is functioning properly. If A/C pressure is not 41-426 psi (2.9-30.0 kg/cm2 ), ECM will disable compressor. Observe A/C pressure on Tech 1 scan tester for 2 minutes with engine idling and A/C on. If pressure is out of range, adjust A/C refrigerant charge. Tech 1 scan tester should be within 20 psi (1.4 kg/cm2 ) of actual pressure. If Tech 1 scan tester pressure reading is not within 20 psi (1.4 kg/cm2 ) of actual pressure, refer to CODE 66 chart in appropriate G - TESTS W/ CODES article in this section or replace A/C pressure sensor.
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Use the Manual With the Right Hardware
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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.