I have posted a couple days ago for intermitting AC problem. At first I thought it was the low pressure switch. But today after playing with it more, I have observed the followings:
1. When I turn on the AC, compressor sometimes kick in, sometimes not. But once it kicked in it'll stay working.
2. I tried to put my ear close to the vent, about 5 seconds after I turn on AC there was a slight click behind the vent, and the compressor kicked in at the same time (judging by the change of engine speed). Sometimes there was no click after I turned on the AC, and the compressor did not kick in.
3. If I turned on the AC, and the compressor did not engage, I was able to make it engage by hitting the top of the control panel (the flat area below center vents) a couple times using my hand. It did not work every time, but 4 out of 5 times the compressor engaged after a couple hit.
Judging from what I have found, is it safe to say that somewhere in the control panel has a loose contact? If that is the case, how hard is it to take it out? I already went through the relavent part in the FAQ but do not quite follow the procedure. THanks in advance.

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1994 944NA 100K miles