The evaporator temperature sensor can fail, causing the AC compressor not to cycle. If the AC compressor does not turn on, the AC system will not blow cold air. If the compressor is stuck on, the air will be very cold at first, before warming up.
Problems for specific Mercedes-Benz S500 years:
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Repairpal verified 2003 Mercedes-Benz S500 problems
The crankshaft position sensor may fail. Symptoms of this are: The engine will crank—but not start—especially when the engine is warm. The car may start again if it is left to cool off, but it may run roughly or have poor performance.
The center console armrest can break. Replacement is commonly the recommended repair.
Analog Tele Aid units are no longer supported and must be updated to digital, preferably at a dealership or a well-equipped independent shop. The update and all related factors should be completed at the same time.
An engine Oil leak may develop from the PCV vent housing on the valve cover and/or the inspection plate on the front of the engine.
The rubber bond in the harmonic balancer can decay, which causes the balancer to move and work its way toward the timing cover. If the balancer comes into contact with the timing cover while the engine is running, it will fracture and damage the cover and potentially other surrounding parts. The harmonic balancer should be inspected at every service.
The electrical connector at the automatic transmission may leak fluid. Over time leaking fluid could migrate through the wiring harness and damage the transmission control module. If that happens a new harness and control module may be necessary to correct the problem.
CD changers, command units, voice control units, PSE units, and Tele Aid units are prone to failure, especially in early models.
Problems with the pneumatic system can cause closing assist and door lock issues.
The relay which turns the airmatic suspension pump on may fail causing the pump to run continuously. This can result in failure of the pump motor or a dead battery as the pump motor will continue to run after the car is turned off. Also, Worn airmatic pump mount bushings can causes noises in the front axle while driving on bumpy roads or a buzzing noise while the pump is running.
The brakes may begin to squeak at about the 50 percent wear point. This is due to the size and material used for the brake pads and rotors. The brake rotor surfaces become uneven, causing a lip to form at the outer edge. This will generally require replacement of the rotors when the pads are worn (pad life varies depending on driving style and terrain).
Leaks may develop from the differential cover and/or seals on high mileage or older vehicles. Our technicians recommend a complete reseal of the differential unit if these leaks are addressed.
An engine oil leak may develop from the oil level sensor. Replacement of the leaking sensor will commonly correct this concern.