AC help needed on 88 190e 2.6

[bpaz_ph]

Hi guys,

I just read saumil's AC diagnostic guide. But before checking the elctronic side I'd like confirm if the mechanical side is normal. Last summer the AC was working fine though not too cold.

At the start of this summer it didn't work at all and my mechanic said it's almost empty of freon. So we re-charged it but still the AC won't kick in. So he did his thing checking the AC components. Then we opened up the klima relay and placed a piece of paper to push the contact forward. We put it back in and this made the AC work.

My mechanic's conclusion is that I need a new klima relay. In short I don't agree with him. I re-checked the low side pressure with a cheap gauge that comes with the can. With the engine running I read 80 when the AC's off. When I turn on the AC, I see the gauge go down to 35 for a second then it goes back up to 80 (I think the unit is PSI). When I turn off/on the AC it doesn't happen anymore. But i can duplicate it if I turn off the engine entirely. I'm thinking that it might be the RPM sensor cutting out?

I also recently flushed my power steering pump and spilled some possibly on the compressor. Can this mess with the RPM readings? If yes how do you clean the compressor clutch?

Thanks,

Ben