Eng rpms go up. on 1995 Lexus LS400

When I turn on the A/C the eng rpms go up, and makes the car
idle rough.

1 answer
It's normal for the idle speed to rise when the A/C is on but the engine shouldn't run rough. I assume that the check engine light isn't on or you'd have mentioned it. I'm thinking that the A/C compressor may be seizing up and causing the engine to stagger or there may be an ignition or fuel problem.
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