Cold Start, Loud Noise, Lights Dimming And Rpm's

[Kara Aultman]

So, I just purchased a 99 RX300 and I absolutley love it. I live in OH and it's a whopping 21 degrees out. Needless to say, I started up the car before I was getting ready to leave and went back inside to let it warm up for a bit. A couple of minutes later, I heard this loud screaching noise. I went out side and noticed the headlights were dimming and brightening back and forth. I got in the car and noticed that the RPM's were "jumping" too... Not a lot. It never went over 1000 RPMS but it would go down low and then go back to 1000 and then back down (and so on). Has anyone had this problem? I've looked at some other forum posts and it looks like it may be the alternator or possibly the water pump (which I don't think this is the case). My friend, who is a Toyota mechanic was there when this happened and he guessed the alternator as well.

[pj8708]

Hi Kara and welcome to the Lexus Owners Club. 21" sounds balmy!....since it's 10' here (Des Moines).lol

I am not an expert, some of those will chime in here latter, but I would agree with your friend. Alternator. Maybe the belt is what was screaching.

Feel free to take advantage of your membership and post as often as you like.

Paul

[jaswood]

Normally the A/C compressor would be disabled with the OAT below ~35F, but with the engine running and the vehicle stationary the OAT sensor, mounted just forward of the condensor/radiator "stack", might well be HEATED radiantly.

Running an A/C compressor at these low OAT temperatures might well result in compressor "slugging", liquid refrigerant entering the compressor intake, resulting in the compressor stalling, locking up rotationally. Thus you get the belt SQUEALING sound. Regarding the up and down revs that might be due to the fact that the engine ECU tries to compensate for the extra load of the A/C compressor when the compressor is enabled.

As a result if encountering this very same exact problem in my '92 LS400 and relocating the OAT sensor accordingly, within days of purchase my '01 RX300's OAT sensor was relocated to a "grille" opening just below the driver side front headlight.

After years of owning my '01 and adapting myself to remember religiously to keep the A/C off throughout the non-cooling use period I discovered that my '01 has 2 C-Best options that could "set" to be more in my operational favor than the factory defaults. With those options now set otherwise I can use the A/C PB to disable my A/C INDEFINITELY and it is FULLY unlinked from automatic operation in defog/demist mode.

[jaswood]

Be aware, the '99 and '00 RX300 models were/are highly subject to premature, 80-100,000 miles, transaxle failures. Design flaw that persists to this day, overcome via DBW, RX330 and later..