The brief
The E350 came in for routine maintenance, and the multi-point inspection that goes beyond the oil and filter caught two jobs: the aircon compressor had failed and the front brakes were worn, the pads down and the discs scored. The owner had it all done in the one visit, which is the efficient way. The compressor is the pump that compresses the refrigerant so the aircon can cool the cabin, and when it fails there's no cooling, plus a broken-up compressor can leak debris through the system, so it needs replacing properly, with a flush, a fresh receiver-drier and a recharge. The front brakes do most of the stopping, the pads are the wear item and the discs they clamp wear and score, and once the pads run low it's pads and discs together. So it was a service plus a compressor renewal plus a front brake axle set.
The diagnosis
The inspection went through everything. The compressor wasn't building pressure, its internals worn, and it had let a little debris into the lines; on the lift the front pads were worn near the end and the discs scored and below minimum thickness, the calipers fine, the rears with life; the oil and filters and a couple of fluids were due. No other faults stored. So it was a maintenance service plus a compressor replacement, with a flush, drier and recharge, and a front brake axle set.
The work
The engine oil and filter were changed, the air and cabin filters replaced and the fluids topped. On the aircon, the refrigerant was recovered, the failed compressor removed, the system flushed, and a new genuine Mercedes-spec compressor fitted with a fresh receiver-drier, then pulled down to vacuum and recharged with the correct weight of refrigerant and oil. On the brakes, both front discs and the worn pads were removed, the calipers cleaned and greased, and a new genuine Mercedes-spec set of front discs and pads fitted and bedded in. A road test confirmed cold air at the vents, quiet, even, progressive front braking with a firm pedal, and steady running.
The outcome
Cold air at the vents, sharp quiet front braking on a new axle set, fresh oil and filters, and the E350 back on the road with all three jobs done in one visit. The car went home serviced and sorted. A failed compressor and worn brakes are exactly the things the inspection is for, so catching them and doing them properly while it was in kept them from becoming separate trips.
