I think you should be more specific on your Q.
When you say AC works I presume all is fine but when you say it does not work-- Do you mean that you get air from the vents but not cold. Does your vents behave properly. I mean does all air come from front vent or nothing comes from front vent. Do yoy hear the blower motor or no. Please be specific and we can help you.

For now do this.
On the receiver dryer there is a pressure switch with two spade connections on it, gently pull them out one by one and clean the contacts and make sure to put them in same place.
Second trace those wires further down and you will find another connection. Most of the times a bad connection here gives an on/off kind of behaviour to AC. Clean them nicely and reattach them.
On the AC compressor there is a set of wire, make sure they are not loose and well connected.

Does you Auxillary fan come on?


Hope this helps.
MVK

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1985 300D Turbo 179,000miles