What causes the air conditioning in a Mercedes R350 to not cool?
3 Answers
There are many reasons why the air conditioning may not cool, mainly related to the compressor and refrigerant. Loose drive belt of the car air conditioning compressor: Car cooling relies on refrigerant, and the refrigerant is transmitted by the air conditioning compressor. The drive belt is an important moving part that drives the compressor. If the drive belt is loose, the compressor may slip during operation, leading to reduced transmission efficiency, decreased compressor speed, and reduced refrigerant delivery, resulting in the car air conditioning not cooling. Substandard refrigerant and refrigeration oil: If the refrigerant and refrigeration oil contain excessive impurities, it can clog the car air conditioning filter, leading to increased resistance and reduced refrigerant flow to the expansion valve, resulting in insufficient cooling capacity.
I've worked on many cars like the Mercedes R350, and there are usually a few possibilities when the air conditioning isn't cooling: First, it could be insufficient refrigerant or a leak, which is common in older cars because the pipe joints or condenser might have small cracks causing leaks. Second, the compressor might be faulty—if the compressor isn't working, the cooling cycle is interrupted. Third, the filter might be clogged or the expansion valve might be malfunctioning, leading to poor airflow. Fourth, there could be electrical issues, such as a blown fuse, a stuck relay, or poor wiring contact. You should first check the fuse box, usually located in the engine bay or under the glove compartment, and try replacing a fuse. If the problem persists, I recommend not trying to fix it yourself and heading straight to a 4S shop or a professional repair shop—they have the tools to measure pressure and accurately diagnose the issue. Avoid running a faulty AC for too long, as it can increase the engine's workload.
Having driven for many years, the issue of the Mercedes-Benz R350's air conditioning not cooling reminds me of when my own car had problems. Most of the time, it was due to a refrigerant leak, as rubber hoses tend to deteriorate over time with prolonged use. Another possibility is that the air conditioning compressor isn't working—you can check by turning on the AC and listening for any sound; if there's no noise, it might be broken. Or, the filter could be clogged with dust, affecting the cooling performance. I usually start by checking the cabin air filter, which is located in front of the passenger seat and can be replaced easily. If the AC still doesn't cool after cleaning, then I check the refrigerant. For safety, avoid driving at high speeds on hot days—it's too risky. Instead, have a professional use a pressure gauge to locate the leak. Addressing small issues promptly can save you from expensive part replacements later.
