On our 87' 300sdl our a/c wasn't cooling very well. I set the climate control knob to min. and set the rpm to 2000. The vent temp drops to about 60 deg. then the a/c clutch starts to cycle on and off.

On my service cd I read about the a/c clutch control module. I removed the module and found the two wires that can be shorted to engage the clutch all the time. When I did that the clutch stayed engaged and the vent temp. got down in the mid. 30's!

I've read posts about a evaporator temp sensor. I thought I found it in the air box above and to the right of the fuel pedal.
Pulled it out of the air box and ran it (still plugged in) and the clutch did not cycle. put it back in the air box started to cycle again @ 60 deg. vent temp.

Ordered a new sensor from the dealer. After the third switch they finally got the correct one?! All of them said evap temp. sensors on the package! He even showed me three of them on his MB computer screen for our car? Plugged in the new switch and no improvement?! All of these tests were done at 75 deg ambient temp., 50 % humididty.

What do I do now?

I hate to keep throwing parts at it!

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87' 300sdl