I have a 85 FJ 60. When I turn on the AC, the engine surges with high and low RPMs. What needs to be adjusted or changed to maintain normal RPM with the AC on?

Thanks.

Paul 91103

 

Paul,
It is normal for the rpm to go up when the A/C compressor kicks on and then to drop when the A/C compressor kicks off.
If your A/C system is low on refrigerant then the A/C compressor will cycle off and on and this will cause the engine rpm to go up and down.

This may not be the cause in your case, but it is a very common cause.
I would suggest that you pop the hood and see if the A/C compressor is cycling off and off.



Fred