My climate control compressor is kicking out on my 94 town car

My climate control has started acting up on my 94 town car. It cools great most of the time but will just start blowing hot air from time to time. Messing with
the desired temp setting will get it to come back on sometimes and so will switching between normal and max ac sometimes. The blower speed doesn't change when the compressor kicks out. It just gets hot in the car. Any ideas what to check? Where is the ambient temp sensor?

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