Mercedes Benz repair: 87 300sdl, condensor fins, correct direction

Question
QUESTION: A/c unit works when car is first started, after driving to town to go shopping, a/c will not come back on on the return trip. Is this temperature/pressure related. Has new compressor/filter dryer 134a system?

ANSWER: i really cant give you an answer due to when you say the a/c will not come back on as in your blower motor will not come back on or your a/c is not getting cold again?when was the last time the thermostat was changed. could be pressure temp related a stuck bypass valvecheck your condensor fins, and your blower motor operation. flush your fluid also

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QUESTION: The blower does work, the compressor doesn't engage. Cooling system flushed last year and new thermostat installed, radiator and condenser fins are clean. Electric fan does work and is turning in correct direction.

Answer
did you buy a new a/c condensor the one that looks like a canister also or was it used. It is odd that it would work then not unless a valve in your system gets hot and closes then it cools down and wil start u[p again I would first replace the thermostat for $$ reasons just incase it is shot and cheapest then I would look in the a/c sysem auxillary fans kick on when you put on a/c if not youll overheat your car. Normal operating temp on MB is 80-100 degrees if you go over 100 your secondary fans would kick on to relase the heat. go to benzworld.org and plug in your profile and do a search on a/c sytem