2001gs300

I have a 2001 GS 300. My passenger side is not blowing heat. If I turn the heat all the way up, it blows cold air then gradually gets slightly warm. Gradually means, the drivers side is already blowing super hot air and the passenger side still hasnt even started to get warm (and never gets past "warm"). I've tried it with dual ac on, and dual ac off.

Can someone please help? Going to Colorado next month and that's gonna suck for who ever is in the passenger side... LOL!

I have been trying to research how these AC systems work to see what could be causing the problem. Seems like a common issue that can be caused by a number of different reasons. Some say thermostat, but I dont think that could be it because I have no issues with overheating, and plus that would affect more than just the passenger side, right?

Please help. All suggestions are welcome.

jsl55

Check the coolant level in over flow reservoir, but its most likely a problem with the pass servo damper for airmix.

2001gs300

Thanks, I'll try that. Did you have this same issue, or something similar?

If anyone else has any suggestions, please keep em' comin'

jsl55

Im a lexus tech

lxtauto

Check for codes. if you raise the rpm to 3000 for 3min the passanger side gets hot or not. if yes,check for air pocket in the coolant system or low coolant.

2001gs300

then I say to you... YOU ARE THE MAN. It's dark and 46 degrees out there (in Florida if you can believe it!), so I didnt check the coolent level in the resv. (though I agree with you that it is probably not the case). I will have to do that in the morning and get back to you.

I did run try to auto-calibrate by turning the ingnition to the on position and then holding down AUTO + RECIRC. It gave me a few codes. 21, 24, 31, 41. The 21 and 24 came on because I was doing it at night. I am told that those codes are light sensor codes. After your original reply, I did some more research on the pass servo damper (I assume the "pass" is for "passenger", right?). I think the 31 and 41 have something to do with the airmix damper. I have a diagnostics document that refers to:

DTC B1431/31 SHORT TO GROUND OR POWER SOURCE CIRCUIT IN AIR MIX DAMPER POSITION SENSOR CIRCUIT, and

DTC B1441/41 AIR MIX DAMPER POSITION SENSOR VALUE DOES NOT CHANGE EVEN IF A/C CONTROL ASSSEMBLY OPERATES AIR MIX DAMPER CONTROL SERVOMOTER.

To me, that means (in a nutshell) somethings wrong with 2 things (and the second might be caused by the first).
1. There is an power (for lack of better terms) issue. Possibly a blown fuse(?).
2. This lack of power is keeping the servomotor from working.

Based on your knowledge, am I close?

Where do you live? If you are in Florida you could earn some extra bucks helping us out with maint. The entire family drives lexus. We believe in the product.

Thanks for your help so far. Even if I do have to go into the dealership, atleast I might seem like I know (a little) about what I am talking about.

2001gs300

Thanks, I'll look at that in the morning too.

You wouldnt happen to be a Lexus tech too, would you? Or maybe you've had the same problems.

Either way, thanks for the suggestions dude!!

2001gs300

Thinking more about what you said...

Wouldnt a low coolant level affect the entire system, and not just the passenger side? The reason why I am curious is that I have heard a "gurgling" (like water, or coffee brewing) noise behind the dash. Usually when I accelarate. I have heard that this is ususally air in the system. I dont know if this is entirely related, but either way, it's probably not good. I have heard that there is a way to bleed the air out of the system. Like a valve or something. Have you heard of this? Would you recommend this, or is there a better (more effective, or more correct) way to do this?

Thanks again.

lxtauto

Well I was a Lexus master diagnostic specialist for 16 years, but now I own my own shop ****************** in MD. Reset the codes and check again.

2001gs300

Very nice. You mainly work on Lexus? I love these cars. Every other manufacturer could drop off the planet and it wouldnt phase me one bit.

Can you clarify "reset the codes"? Do you just mean for me to try it again, or is there something specific that I have to do to reset before I try it again?

If you ever move your business to Florida (where it is sunny and warm!... except right now!), I am sure you will find plenty of business! I know a lot of lexus owners! You can steal jsl55 from the dealership and bring him down to work with you!

lxtauto

remove the (-) battery post for 2 min that will clear the code and then start the car and chek codes. but sound like you have an air pocket take care of that.

2001gs300

I checked the coolant level. It was low, but I dont think it was affecting the Dual AC issues. Ran the car for 3 min at 3000 RPM and no change to the passenger side. I drained the radiator and flushed it with only water and with not too much pressure. Wasnt trying to do a full on flush, just cycle new water through and try to get any air out. Crazy thing is that, as soon as I got done, the driver's side started acting funny and not giving too much heat. After running it for a bit, and driving around, heat started to come back on the drivers side. I dont know if it was the running of the engine (doubt it cuz I had been running my engine on and off already). Anyway, hope that is not anything new.

I reset and checked the codes again. 31 and 41 are the codes that appeared.

I took out the glove box, CD Changer, etc. to access the servos. There appears to be 3 on the passenger side (behind the glove box).

One, the Air Inlet Servo Motor seemed to control the recirculation mechanism (the one the opens or closes based on whether you are trying to recirculate the air, or have fresh air coming in from the outside. This one was working fine.

The second one, the Air Outlet Servo Motor seemed to be functioning but I found out that it appears to be the source of a weird humming that I hear only when I start the car up. It humms for about 20 seconds then stops. Only when I start the engine. This humming started around the time that the heat stopped if I remember right, but I dont think the outlet controls the temp. I think it controls what vents are open and being used (face vs floor vs defrost, etc.) I took it off and apart to check to see if maybe some of the teeth on the gear had been warn down (that's what the humming sounds like). Its pretty simple inside and didnt look like anything was physically wrong with it. Could the humming be electronic? Could it be related, or just coincidental?

The third one, the Air Mix Servo Motor, is the one suspected of causing my heat issues. I didnt get a chance to take it out and look at it, but even if I did get it out. How can I test it to see if it is the culprit?

I appreciate everyone's help on this. I really dont want to take it to the dealer (or mechanic) because I know with this type of issue it could be the "troubleshoot, and spend money along the way replacing parts (+ labor)", in kind of a "hit or miss" method. I would rather find out the problem, then take it to them and tell them exactly what I need fixed. Everyone's gotta earn a living, so I dont mind paying if the problem is guaranteed to get fixed.

Frustrated! PLEASE HELP.

Thanks in advance

ElitistK

iTrader: (4)

that should be the problem. if you hear a buzzing sound when the car starts up, that means your servo motor is shot.

it's about $350 + labor to replace it. FYI, you will need to take out the entire dash to replace the servo motor.

2001gs300

The motor that is humming seems to be working. It is the Air Out Servo Motor. I can switch it to all different modes and it works right. We might be talking about a different part because I just took the glove box out and completely pulled it out without taking out the dash, and I called my local dealership to ask about both motors (Air Out and Air Mix). They're in stock and one is $165 and the other is $179. The Mix motor seemed a little harder to get out but I dont have to take the entire dash out.

Is there a difference between the "Air Mix Servo Motor" and the "Pass Servo Damper for Airmix", as quoted from the original response that I received?

Thanks

lxtauto

I can fax you the info to check the sensor tomorrow or see ****************** and call me.