I have had leaks in the AC of my C280 and was just told that its teh auxiliary fan not kicking in which is causing a presure buildup and subsequently teh leakage
Is there a simple to test what is causing this ? Is there a presure switch I can check
The dealer puts the cost at $700+ to troubleshoou and fix teh problem
Thanks

I think you will find it to be the other way around..
The aux fan does not come on until the high pressure calls for it. { High thermal heat load]. The fan then draws air across the condenser to help alleviate this high pressure problem before the compressor reaches cut-out safety pressure.
If a system has a leak , the fan will not come on b/c there is no longer enough refrigerant high side pressure to activate the aux fan cut-in pressure spec..
So, a leak will cause the fan to not operate , not the non operating fan causing the leak....

If this is the case couldn'T I simply short out the sensor that detects the high presure and verify the fan is operational and not the cause
Any idea where I would look for the switch?
\Thanks again

Of course you can.. That was the point of my post..

It is the high pressure sw at the reciever/drier .. jumper it and the aux fan circuit should come on..