Mercedes-AMG A45 S condenser leak and suspected compressor oil starvation after repeated refrigerant refilling

Sifu White explains what happened

Prices, repair times and warranty terms mentioned in the video applied at the time. Ask the workshop about current arrangements.

There may have been an earlier leak followed by repeated refrigerant refilling until the compressor was affected. This is a newer Mercedes-AMG A45 S with two condensers, one small and one large. When the car arrived, the compressor was producing no pressure. Inspection found that the oil in the system had turned black. Based on experience, the regular A45 can experience a similar condition.

When a compressor fails and produces no pressure, black contamination can reach the condenser, cooling coil and expansion valve. Not every component necessarily has to be replaced. If the cooling coil is only lightly affected and can still be recovered, flushing and reuse may be attempted. On this car, the compressor and condenser have been affected, while the cooling coil has only minor contamination. This is the smaller condenser at the side.

There is another condenser underneath. On this model, the receiver drier is not built into the condenser; it is a separate component that must be ordered separately. Inspection also found a condenser leak with visible oil traces. The video therefore suspects that the leak had been present for some time and that repeated refrigerant refilling eventually led to compressor failure.

How contamination changes the repair scope

Refrigerant and lubricant travel through several components. Debris from internal compressor wear can therefore create a problem beyond the compressor itself. Installing a replacement while contamination remains in circulation can expose the replacement to the same problem. The investigation should distinguish the source of damage, the spread of contamination and the condition of components that might still be serviceable. Neither “compressor only” nor “replace everything” is a complete diagnosis on its own.

Whether flushing is appropriate depends on component construction, contamination and the manufacturer’s procedure. Fine passages and trapped debris can be difficult to clean reliably. Compressors, driers and metering devices cannot simply be treated as open lengths of pipe during flushing. Oil colour is one observation, but colour alone does not measure moisture content or establish that every component has failed. An itemised explanation should identify what needs replacement, what can be cleaned, and the evidence behind each decision.

Why cooling after a regas does not prove a repair

Refrigerant circulates through a closed circuit; it is not fuel that the engine consumes. If cooling returns after charging and then deteriorates, the investigation should establish whether there is a leak, whether the previous charge matched the specification, and whether another control or heat-rejection problem is present. The initial return of cold air describes performance at that moment. It does not show that a leaking component has been repaired.

A model’s familiar failure pattern is a starting point, not proof. The condenser, connections, hoses, compressor seals and evaporator inside the cabin are different possible inspection locations. An oil stain can guide a leak test, but it is not a substitute for confirmation. Finding one leak also does not clear every other part of the circuit. After repair, the sealing and cooling performance need to be checked again under conditions relevant to the original complaint.

What to tell the workshop about your own car

You do not need to guess a part name first. A clear description of what actually happens is often more useful for reproducing the complaint than requesting a particular replacement.

• Ask for an itemised scope separating contamination work from leak repair.
• Record the last regas date and how long cooling lasted.
• Include the model, year, recent repairs and what changed before or after the symptom began.