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....