where is revolution detecting sensor located ?

i have a 91 camry, i am trying to locate revolution detecting sensor
to fix air condition button that is flushing ?

I realize we may have a language issue here, but I have no idea what you mean. Flushing? And what does the Air Condition button (or the air conditioning for that matter) have to do with the RPM sensor?

ycl1688, you need to get a native English speaker to tell you how to describe your problem. Then maybe we can help.

i mean a/c button is flashing.

Flashing AC light means belt is slipping, rpm sensor is faulty or AC amplifier is faulty. Rpm sensor is located at compressor and should measure 100-130 ohms at 68 degrees F(20 C).

is regulator and compressor same thing ?