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.
A/C System, Operating After Filling Refrigerant Circuit
Only start engine after refrigerant circuit has been assembled.
If possible start engine only with a filled refrigerant circuit.
Do not start the engine while evacuating the refrigerant circuit or when the circuit is already evacuated (the A/C compressor could be damaged). Refer to Description and Operation (A/C Service Station).
The A/C compressor is always driven by the pulley or by the driveshaft (there is no magnetic clutch). To prevent damage when the compressor is idling, it is lubricated by an "internal oil circuit".
The compressor has an "internal oil circuit" to ensure the A/C compressor is not damaged when refrigerant circuit is empty. Prerequisite for the internal lubrication is residual refrigerant oil in A/C compressor.
The engine may only be started when the refrigerant circuit is installed correctly. For example; if the refrigerant lines are not connected to A/C compressor, when the engine is running the A/C compressor may heat up (via internal heat generation) so much that the A/C compressor will be damaged.
A/C Compressor Regulator Valve -N280- is not activated when the refrigerant circuit is empty and the A/C compressor idles with the engine. If there is no refrigerant, then the refrigerant oil, which is needed to lubricate the A/C compressor, will be not be transported (the A/C compressor will be lubricated by an "internal oil circuit").
If it is necessary to start the engine with a discharged refrigerant circuit
- Refrigerant circuit must be fully assembled.
- There must be no vacuum in the refrigerant circuit.
- At least 1/4 of the prescribed refrigerant oil must be in the A/C compressor.
- Do not rev engine higher than 2500 rpm.
- The engine should only run as long as is absolutely necessary.
Note the following when starting engine for first time after filling refrigerant circuit
- All removed parts are installed once again.
- The refrigerant circuit is filled with refrigerant. Refer to Specifications .
- Follow the information on servicing the A/C system after installing the compressor. Refer to Description and Operation (A/C Service Station).
-- Start engine with the A/C compressor switched off ("Econ" operating mode set, indicator light in AC button does not light up), and wait until engine idle speed has stabilized.
-- Open all instrument panel vents.
-- Set the temperature preset on the Climatronic control module -J255- to "cold".
-- Press the AC button to switch on the A/C compressor ("Auto" mode selected and the indicator light in the AC button is on) and let the engine and A/C compressor idle for at least 5 minutes.
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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.