Oil in coolant reservior/No A/C

[jagarundi]

Hello everybody, so here's the deal:

Started noticing oil in my coolant reservoir last winter. Flushed it out and kept on keeping on. Heat was fabulous and the silver shadow never over heated. Fast forward to now. Noticing oil in the reservoir as a constant now but no coolant in the oil. When I went to turn on the AC for the first time a couple weeks ago, nothing but hot air and noticed that my aux fan wasn't spinning. AC was working like a champ last summer.

I take it in thinking my Freon was done and was told my Freon is full. Fan wouldn't spin unless the mechanic disconnected the compressor sensor (?) and then it spun up like crazy but still no cold ac. He then suggested that I get a compressor or condenser sensor and try that before springing for a new AC compressor altogether.

My question is...could the oil in the reservoir cause this issue or are they two completely different issues?

First question is: What would cause oil to leak into the coolant reservoir?
Second question is: Why isn't my ac working? How do you test the compressor, which seems to kick in whenever I turn the AC on but just blows hot air?

BTW, I changed my FSR a couple years ago so I don't think that's an issue....

[srmmmm]

The oil in the coolant usually indicates a leak in your oil cooler. Oil pressure in the engine is higher than the pressure maintained in the cooling system so oil get forced through the leak in the cooler into your coolant. The A/C not working is totally unrelated. I would generally agree with your mechanic that the pressure switch on the compressor is defective and not triggering the auxillary fan to come on. It would be best to have your error codes scanned first though before buying parts you may not need.

2002 X5 3.0 303,700 miles
2014 428i 19,000 miles

2004 325i sold at 123,600 miles
2001 325i sold at 66,000 miles

1970 Firebird - undergoing restoration

[g300d]

That could be auto trans oil, crossing over at the coolant/trans fluid heat exchanger.

Had that happen to me with same symptoms...oil in coolant but no coolant in crankcase.

Diagnosed it by having a rad shop pressure test the heat exchanger.

As mentioned I dont think it's related to your AC problem.

AC problem can be a few things. I would have it diagnosed professionally.