Why is the air conditioning in the Mercedes-Benz E260 not cooling?

[Terry]

Here are the reasons why the air conditioning in the Mercedes-Benz E260 is not cooling: 1. Refrigerant leakage in the air conditioning system: The lack of refrigerant due to leakage causes the air conditioning to not cool. The solution is to add refrigerant along with fluorescent dye. After driving the vehicle for a while, use a dedicated UV lamp to inspect the air conditioning system. If there is a leak, the affected area will glow, and the leaking component should be repaired or replaced. 2. Low engine speed: When the car is idling, the low engine speed causes the compressor speed to also decrease. Combined with insufficient refrigerant, the instant pressure boost fails to meet the standard, resulting in low high pressure and the air conditioning not cooling. Observe the sight glass on the top of the dryer. During normal operation, if continuous bubbles appear in the sight glass, it indicates insufficient refrigerant. If the bubbles flip, it means the refrigerant is severely insufficient and needs to be replenished. 3. Damaged expansion valve: A damaged expansion valve prevents the formation of high pressure in the system before the valve, and the high-pressure refrigerant cannot reach 150 Kpa. This causes the evaporator behind the expansion valve to fail to cool, leading to ineffective air conditioning. Internal wear in the air conditioning compressor results in insufficient pressure (150kpa to 200Kpa) between the compressor and the expansion valve, preventing normal refrigerant circulation and causing the air conditioning to not cool. If severe internal wear is found in the compressor, replacing the compressor will resolve the issue.