My nearly new car has persistent air con problems - should I reject it?

I have owned a BMW M140i from new, the car is nine months old and has suffered persistent problems with the air conditioning. The local dealership has failed to fix them, so I took the car to the supplying dealer with an ultimatum to fix the car or I would reject it. Since working on the car, they have discovered that the charge air cooler (intercooler) located in the intake manifold has been leaking coolant. I have seen a video from the technician and the cylinder head intake ports and valves are caked with dried coolant residue. The dealership are proposing to clean the cylinder head and replace the faulty parts (as well as fix the air-conditioning), but I am worried about the valve seats and wider long-term damage that will have been done to the engine due to ingestion of water vapour over an extended period. What course of action would you recommend?
You write a letter to the dealer principal of the supplying dealer stating that the car was faulty as supplied and that you wish to reject it, citing the ruling in Clegg v Olle Andersson, House of Lords, 2003. But if the supplying dealer will offer an unconditional five year warranty on the engine after the repair you would be prepared to accept the car back in a repaired state. Send it by Post Office special delivery, keep a copy, and staple the certificate of posting to the copy so that it becomes a matter of record.
Answered by Honest John on

Ask Honest John