Does anybody know the differerence in part numbers for the aux fan low speed switch which is located on the receiver dryer for my '92 300E? It is part 65 on the MBZ parts diagram with two part numbers-1248213651 and 1248208310. They seem to be interchangable. Could it be that the pressure to turn the aux fan on and off is different? Thanks for any help.

The xxxxx310 is the aux fan sw. The other is system pressure sw.

http://catalog.peachparts.com/RenderScriptTemplate.epc?_cmd=epccat_VehicleAAA&cookieID=2FG17RJ3A2GH0VFWLU&yearid=1992%40%401992&makeid=MB%40%40MB%40%40X&modelid=300%2DE%2D002%40%40300E&catid=R%40%40Climate+Control&mode=PA&subcatid=R1055@@A%2FC+Temp%2E+Switch&source=www.peachparts.com&clientid=catalog.mercedesshop

What makes you think the sw. is bad? That switch is one of the most commonly mis-diagnosed switches.

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A Dalton

Thanks, Arthur. I will make sure this is the problem!!!

If you jumper the pigtail leads of the fan switch w/key ON , you should get low aux fan activation..that test the integrity of the low fan/ac circuit..BUT, that test does NOT always mean the sw is at fault. It simply means the relay/fuse/fan. etc test as OK. The most common cause if that test condition is met is a slightly low refrigerant level. That allows for a/c cooling, but not enough high side pressure to trigger the aux fan switch cut-in spec.....that is where the mis-diagnosis comes into play...guys think that the sw is bad when the actual correct diagnosis is low refrig level.
Gauges are the tool ..[ or, in the case of R12, a quick look at the sight glass will tell the tale]

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A Dalton