Hey Guys!

I've got something odd going on with my 95 blazer when I have the A/C on. While accelerating the RPMs will drop by about 200-300 every 3-5 seconds. Idling seems to be ok, its only on acceleration and only when the A/C is on.

 

its because your A/C uses a compressor.
your compressor is turned by your belt on the front of your engine.
while your A/C is off it is able to rotate freely causing no drag on your engine.
but when you turn you A/C on, the compressors "clutch" kicks in, which puts a load on your engine.
its totally normal so dont worry.

 

It shouldnt cycle that quickly. It is actually something to worry about. Chances are the refrigerant charge is low and the low pressure switch is shutting the compressor down when the pressure gets too low. Cycling that quickly will cause the clutch to fail prematurely. It wont harm the engine but the compressor is paying the price.

 

very true.
didnt really think about the 3-5 seconds he said.
normal one should cycle about every 15 seconds or so.