My 1998 GS400 A/C will not runs automatic, always on the highest blower level. Please help.
Thanks.

 

Can you be more specific, are you talking about the blower speed, in general, or you're saying that each time you push the AUTO button your blower kicks up to high speed..?

If you're talking about your blower motor speed stuck on high regardless of what fan speed you select, then you might have to replace the control blower motor, I think it's part 87165-22040; I just did this on my 99 GS3 with a little over 200k miles; very easy to replace but you will need a short screwdriver.

If you're talking about the blower speed kicking on high when you push the AUTO button, then it might be okay depending on the cabin temperature compared to what you're telling the system to adjust it to; kicks on high to try and cool it down (warm it up) as quickly as possible.

Hope that helps a little.

 

When I push the AUTO or A/C buttons the blower fan always go to highest level no matter what temperature I set. Thanks for your info I will check into it.

 

There might also be a problem with the interior temperature sensor (i.e., it thinks the interior is always hot). Hold down the auto and recirculate/fresh buttons on the climate control and turn the key to the on position. It will go through a display check for a couple seconds and then list codes for any problems it has detected. If anything pops up, post the codes here and we can go from there.

 

error code 21 and 24. Thanks

 

Those are codes for the driver's and passenger's solar sensors, they aren't anything to worry about as they pop up when you look at codes in a relatively dark area. I would say the problem is, in fact, the blower control module.

 

Might want to check the Blower Motor Controller, part number 87165-22040. This part has been superseded by part number 87165-22050. Could check that. There is a right up somewhere around here...

 

Thanks for all your help. I bought Blower Motor Controller on EBAY $148, replaced it and it works perfect.
Lexus dealer estimated to fix this problem for $900.00.