Vibration When A/c Is Turned On

[BMAN1113]

When I flip on my A/C I get a slight vibration or roughness that I can feel especially in my pedals. Then sometimes it won't vibrate at all. Is this pretty typical of other SCs?

Thx

[jzz30]

either the compressor is running rough or the motor and trans mounts need to be changed.

[knmaynard]

I've had a 95 SC400 for about a week now, and I've noticed the same exact problem. Turn AC on/off, & vibration seems to correlate.

No ideas, just letting you know it's doing it on mine too.

Mine sat for the last 7 years (14k miles during that whole time) so I'm wondering if an oil charge would help, maybe it's running rough because it hadn't been used for so long.

Any ideas appreciated.

[Bly]

I've got the same issue on a 2002 SC430. It's done it since new. I've had it into Lexus several times (as recently as yesterday) and have been told the same thing at two different dealers. That it's just the compressor and it's normal. I actually think that the computer chip is mapped wrong and should increase the idle a little more when the AC is on but what do I know.

[BMAN1113]

What I think is wierd is that it happens sometimes and not others. I'm wondering if it is a motor mount. You know, Come to think of it I noticed the same feel in a new suv loaner they gave me last year. I dont know.

[lexcalibur300]

Air Conditioner Compressors can vary in their smoothness based upon fit or wear condition of the shaft bearings. The reason vibration is intermittent is because the A/C triggers on or off according to thermostat temperature setting. When compressor kicks on cooling the air, the compressor bearings under significant additional load doing its job. On some cars, if the belt driving the compressor is installed way to tight, that can lead to premature failure of the bearing behind the front pulley.

Normally compressor bearings wear and become rougher with age -- but they can last several years running kind of rough. New compressors should be smooth, although you can still sense when they kick on and off as a rule. There should be barely discernable vibration or noise with a new Lexus -- if so, the compressor not up to standard quality.

Check brackets or mounting braces to make sure bolts are tight and that bracket has not cracked as this will cause vibration as well.

Good Lexus Luck....