e-man

I always run my climate control on auto with the a/c on, so my RPMs are consistently at 650 or so (car in drive, at a complete stop). If I ever turn my climate control off (or turn the a/c button off), I get the dreaded low idle. Obviously, the easy solution is to always drive with the climate control and a/c on, which I do.

Over the last few weeks, though, we've had some pretty cold weather here in Chicago, and I've experienced a low idle (like in the 250 range) at stop lights with the climate control on auto (set to 72) and the a/c on.

I think what is happening is the compressor is turning off because the outside air is so cold and dry (even though the green a/c light stays on the entire time). When I experience the low idle, sometimes if I lower the temperature setting a few degrees, the a/c compressor kicks back on and the RPMs shoot up to a normal range (although this morning, that trick didn't work and I had to turn the headlights on to increase the RPMs).

Here's my question. Does anyone know if there's a way to force the a/c compressor to stay on?

e

engin_ear

iTrader: (1)

e, I've found that this problem has pretty much gone away for me since I got the SRT intake. It may have to do with the air filter and airbox choking the engine, not sure. You may want to try the K&N intake.

chuckb

push auto and set to 65, then lower than fan speed manually to lowest setting, it should stay like that.

I'm a bit annoyed that Lexus never took care of this from 1998-2005. that's ridiculous.

engin_ear

iTrader: (1)

Yeah Chuck, agreed, there's a short list of things that they never addressed (including the pretensioner).

e-man

But I'm cold!!!!!!!!!!!!!!!!!!!!!!!!!!! Seriously, it's freakin' freezing up here and I want to run the heat. What triggers the compressor to kick on? Is it related to outside temperature or humidity? For example, if I set the inside temp to 65 and the outside temp is 32, it seems to me that the compressor wouldn't need to turn on because the outside air is colder than the desired setting, right? Then again, maybe it's tied to humidity because most mornings lately the temperature has been in the 50s (which is lower than the set temperature in the car) and I haven't had a problem. I'll fiddle with it tomorrow on the way to work.

e-man

Hey Jerry. I've got a K&N drop-in. Does that count for something?

chuckb

just turn your parking lights on then.

e-man

Yeah Chuck, I could do that, but I shouldn't have to. Also, what's weird is that most of the time it's fine. I'm thinking that it must be tied to outside relative humidity. If the outside air has some level of moisture in it (which, around here, is most of the time, even in winter), the compressor kicks on to dry out the air.

LEXSOOS

Most likely it's related to outside temp.
I would keep head lights on instead, fuel consumption is lesser than with A/C on, but that's only me

engin_ear

iTrader: (1)

Counts for a little, but you still have the airbox & resonator thingy. Make sure your filter is cleaned and oiled.

slickgt1

iTrader: (1)

I tried the K&N filter. Problem still there. I changed the little rubber O-ring on the MAF sensor (thought that it was leaking). Problem still there. Cleaned out the TB and MAF sensor. Still there. I have been told that it could be a Throttle Pedal Possition Sensor. Doubt it. I thought it was the mounts at 100k miles starting to go bad. But my SC430 is newer with 50k miles, and it does the same exact thing. As soon as the car is fully warmed up, starts to shake/low idle. Turn on the AC or lights and it goes away. I don't know what else to try, other than that TPPS.

engin_ear

iTrader: (1)

Can this be due to aging vacuum hoses?

Bill_GS3

Just a question, have you guys cleaned your throttle body at all or the MAF meter? I've worked on lexus for six years now and haven't ween the problem you guys are talking about. I also switch my ac off all the time when it's nice out. Instead of finding a way around it why not fins out why it's happeneing, there has to be a reason.

-Bill

chuckb

I think it's only the V8s.

IAGS400

I'm willing to bet it's due to a bad sensor or a sensor that needs adjustment. On my Ford SC this problem is caused by a mis-adjusted TBS sensor on the throttle body.

e-man how long has this been going on? Was this happening before you cleaned the TB?