frankzan

ok guys I've searched this forum high and low but I cant find out why the air condition, when turned on causes the idle to raise and makes the car very difficult to keep stopped when in traffic. I spend the majority of my commute in traffic for close to 45 minutes and when the air is turned on the idle rises about 200 rpm and i have to ride the break to keep it from pulling the car ahaead. I plan on bringing the car in on Tuesday to have steel brake lines installed and replace the seal in my oil pan thats been leaking since my switch to synthetic oil two weeks ago.

Any suggestions on what might be the problem with the A/C would be greatly appreciated.

Thanks
Frank

GRAND_LS 4

iTrader: (2)

Hey and welcome to ClubLexus!!

I wish everyone knew how to title threads like that.

Now on to the car, you say it raises the idle, which is normal in every car. But just so we can further understand the issue, what is the idle before turning on the A.C. then afterwords.

It maybe too low to begin with (very common on the V8's) or it could be highly excessive to begin with as well, and when you turn on the A.C. it gets even higher.

frankzan

Thanks for the welcome GRAND LS, I've been reading through this site for a few weeks now and all the info has been very helpfull. The car at start idles beautifully and stays at about 750 rpm. There is no hesitation at slow speeds or when pressing hard on the gas. But as soon as the air condition is turned on the rpm's jump to 950/1000 and when you need to stop it takes more force and constant pressure to keep the car from pulling ahead. Its almost as if i was holding the brake with my left foot and giving it gas with the right. Possibly too much tension on the serpentine belt?

steveski

Welcome to CL. Just for comparison, my idle when warmed up is about 400 RPM with no AC on. When I turn it on the AC the RPM increases by about 200. Yours seems higher but I don't think the serpentine belt would/could cause this.

Dutch

when you turn on the a/c the clutch engages on the compressor and makes it harder for the crank to turn the compressor pulley therefore increasing the load on the engine making the rpm's rise slightly. its common on all systems

GRAND_LS 4

iTrader: (2)

seems like your RPM is high to begin with. It should be about 600-650 at idle. Has anyone adjusted your TPS recently? (i think tps is the name right? for the sensor above the throttle body that adjusts the idle).

You would have two if you have traction control.

Read up on the sensor, and how sensitive it is, and also how expensive repair can get, and after gathering enough info, attempt to adjust it yourself.

Have a look here:
www.lexls.com

Suneet

The idle for your car (a 93, like my 94) is supposed to be 650 RPM, or as close to it as possible. It definitely sounds like your TPS is not adjusted properly, and thats what would explain the feeling you described of "having to hold the car back'.. when your throttle is at rest, the car actually is behaving as if it is slightly depressed. This also explains why it takes a little extra effort to to brake.

Here's a great tutorial on how to adjust your TPS, its very easy to do:

http://www.lexls.com/tutorials/EFI/tps.html

That tutorial actually shows replacement and adjustment. Yours may need to be replaced if you find that you can't adjust it to specificiations.

Dutch

yeah TPS is right

THROTTLE POSITION SENSOR