As the school year draws to a close and the temperatures climb, it’s time to make sure the air conditioning system in your Mercedes is capable of keeping the cabin comfortable.
Before taking your ride in for service, there are a few basic checks you can do at home. With the engine running, open up the vents in the dashboard and turn the fan on. Make sure the fan speed increases as you adjust the control. If the fan isn’t working or a vent has been blocked, cold air won’t be able to get into the cabin.
If the fan pushes out air, turn the temperature control as low as it goes and within a minute or so cold air should emerge. If the air comes out only slightly cooler or not cool at all, several items could be at fault.
Most Mercedes models typically rely on a belt to turn the compressor. Like the other accessory drive belts for the alternator and water pump, the compressor belt can wear and stretch over years of use. A vehicle that has been on the road for many years may just need a new belt.
If the belt is relatively slack free and it’s visibly driving the compressor, the system could have a leak and/or need a recharge. The refrigerant in the system can slowly evaporate, or leak out, causing the pressure to drop. Virtually any vehicle built since the early-1990s uses a refrigerant called R134a. We can check your system for leaks and recharge it with the refrigerant recommended by the vehicle’s manufacturer.
Vehicles built before the early-1990s actually use an older refrigerant known as R12 . Some older systems need to be upgraded with new seals and other parts to work with R134a. Most older vehicles still on the road have already been upgraded over the last 20 years, but if you have one that’s still using R12, let us advise you.
If the air conditioning is at full pressure and still not generating cold air, the problem could be inside the compressor or perhaps in the heat exchanger. Both of these are problems that should be corrected by a technician who has the tools to properly diagnose the problem and ready access to the parts needed to fix it.
If your car isn’t keeping you comfortable when the mercury climbs, it’s best to get the system fixed before you get stuck in traffic on a steamy summer day.