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.
Refrigerant Circuit Concerns
- Electrical system, vacuum system and air duct fault-finding has not revealed any faults. Refer to Guided Fault Finding for the A/C system using the Vehicle Diagnostic Tester and [For engine(s) BPY, CETA, CCTA, CDMA, CEPB] Diagnosis and Testing .
- The OBD/Guided Fault Finding for the A/C System with Vehicle Diagnostic Tester cannot detect a fault, the A/C compressor shut off condition is not displayed in the measured values block (only on vehicles with OBD "A/C System"). Refer to [For engine(s) BPY, CETA, CCTA, CDMA, CEPB] Diagnosis and Testing or "Guided Fault Finding" using the Vehicle Diagnostic Tester.
For all complaints marked *, refer to PRESSURES, CHECKING .
If a malfunction occurs at only one evaporator in vehicles with two evaporators, also check pressures in the refrigerant circuit.
Observe test requirements. Refer to REFRIGERANT CIRCUIT CONCERNS .
- Total cooling system failure.*
- Insufficient cooling performance at all vehicles speeds or engine speeds.*
- None or insufficient cooling after driving a few miles.* *
- No cooling or insufficient cooling at one or both evaporator(s) (on vehicles with two evaporators).* *
- Compressor, A/C clutch -N25- or A/C compressor regulator valve -N280- shut off by pressure switch (for example, -F73-, -F118-, -F129- -F129- or by A/C Control Head -E87- or Climatronic Control Module -J255-) due to excessive or inadequate pressure. *
- None or sharp decrease in fresh-air supply after driving several miles (evaporator iced up).* *
From these, the following complaints may also occur:
The A/C Compressor Makes Noises
-- Tighten compressor securing bolts and compressor bracket using a torque wrench.
-- Check routing of refrigerant pipes; they must not touch other components and must not be subject to strain (align if necessary).
Noise (Refrigerant Hammer) Occurring Immediately After Switching On Air Conditioner and/or When Cornering Or Braking
-- Discharge, evacuate and charge refrigerant circuit (too much refrigerant in circuit).
Too much refrigerant oil in the circuit could also cause this problem. This could occur if the amount of refrigerant oil was not adjusted when replacing the A/C compressor.
Water Sprays Out Of Vents (In Dash Panel Or Footwell) Although Air Conditioning System Is Otherwise Functioning Properly
-- Check proper routing of condensate drain; it must not be crushed or kinked.
-- Check condensation drain valve, it must not be clogged by wax or underbody sealant and must close properly.
-- Check plenum chamber cover; it must not be damaged and must be properly installed (to stop water running into evaporator).
-- Check water drains in plenum chamber; they must not be blocked (for example, by leaves).
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.