I have a 1997 LS400 and I've had a problem whenever I drive the vehicle for more than approximately 45minutes to 1 hour, the A/C blower motor weakens and doesn't blow through the car's vents "accordingly." What I mean is that when it's on "level 3" (out of a high of 5), it barely feels like a "level 1" (and when it's on "level 5" it'll barely feel as if it's on "level 2"). When this happens, the air coming out (albeit it's a lot less) is still cold and it NEVER gets hot...just the speed and strength of the blower motors WEAKENS.

When the car is turned off for a little while (between 30 minutes and 1 hour), and then restarted, the problem goes away and the A/C system functions perfectly with normal fan speed and strength accordingly.

That being said, I had the alternator checked today and when the A/C is on "Level 1", the alternator is putting out full charging strength. However, if the A/C fan is put on any level between 2-5, the charging is very weak (barely at 12). I went ahead and replaced the alternator as it was determined to have gone bad, and I replaced it with a new alternator. The problem still remained!!! Nothing changed.

Now, with all this being said, my "battery light" in the dash (the one to let you know the charging is on the WEAK side) has NEVER come on. Nor has the car stalled or done anything out of the ordinary. My overhead map light did flicker last night when I drove the car, but neither the headlights nor any other lights have been flickering in the vehicle.

I was told this could possibly be an A/C blower motor "resistor" that's going "faulty" and when the fan speed is higher than level 1, it's pulling too much current from the charging system, hence draining the alternator and showing the charging level to be on the low side.

Does anybody have any experience with this similar problem in the past? Any help?

Please either reply or call me (713-459-6411) as I'm needing to fix this by tomorrow (Saturday 5/23/09) withOUT taking it to the dealership.

Any help you may be able to offer or throw my way is greatly appreciated !!!!!

 

Cabin filter is the first thing that comes to mind. Has this been changed?

 

Try running the blower in max for the same amount of time, it shouldn't weaken because its getting a full 12v... I'm thinking its the blower resistor giving you problems. Find someone that is willing to swap climate control modules with you for about an hour and see if that works...

 

The cabin air filter has been changed. The one it had in the car was terribly worn out and filthy. The problem has not gone away though.

I am going to try to install a used blower resistor / relay from a local junkyard. I will then run the car for more than an hour on a high level on the fan motor of the A/C and see if the problem will get taken care of.

Also, I have replaced the serpentine belt with a brand new Gates belt from O'Reilly. The belt that came out of the car looks like new, so I am now starting to think whether or not the accessory belt tensioner (which is "spring-loaded") could possibly be allowing the belt to "slip" over all the pulleys...?

I should have an update for us all by this coming Monday.

Thanks again for your replies and helpful advice!!!

Let's keep this wonderful forum site going strong...