It was 42 degrees down here in Adelaide yesterday (no fires though!). I had to go out in the kombi (84 Wasserboxer) and put the air conditioner on. Everything seemed normal, engine temp. slightly towards the upper end of normal range.

Suddenly at about 60k the engine lost power and almost cut out. I turned off the aircon and she spluttered and came good. Tried this several times, with the same result.

She always labours a bit with the aircon on, particularly at idling, but nothing like this.
I checked it out later at home and with no load on, the effect of the aircon was normal - just a drop of about 500 revs. There was also a tiny gleam of light from the temp warning light each time I switched the aircon on or off.

Could this have been an airlock in the fuel line, as we used to get going up hills in old cars, on such hot days? It only happened with the motor under the extra load of the aircon.

Any advice most welcome!

Bob

Sorry, correction - I guess she normally drops about 200 revs at idle when the aircon is switched on (no rev counter).

Bob

Dave, injection. And I should have added, I've been driving everywhere since with the aircon on with no repetition of the problem. I'm thinking could it have been something weird the aircon did, although it still blasts out icy cold air OK.

We have 41 degrees forecast for friday and saturday, so I'll see how she goes then.

Thanks.

Bob

It would still be vapor lock (fuel boiling in the fuel line). On EFI cars the fuel rail can get very hot and heat up the fuel very quickly, the hot fuel then returns to the tank. Try feeling the fuel tank and seeing if it is getting warm.

Although since it seemed to be linked to the AC then that may be the prob. There are parts of the engine that will try to increase idle speed to compensate for the air-con being on. Maybe it is linked to that. Who knows, you need more experiments.