airtraffic

Hello everyone!



I have a '95 SC400.. and problems with my AC.. Compressor and system pressure are OK. The problem seems to be in the distribution. I think I have a bad servo motor. I ran the code check using the AUTO and RECIRC button test and got a code "43" which is "Air outlet door servomotor circuit" I am not sure, but I think the is the air mix servo? I can feel just a little air conditioned air coming out one of the vents, with warmer ambient air coming out all of the other vents.. It's as if perhaps the dampers are stuck, not allowing cold air to come out all of the vents? Heat works just fine, as I turn up the control calling for more heat, the temp does increase to full hot. (I tested this on a cool night last night - 60 degrees F) The fact that the mix servo will give me full heat, but not cooling is puzzling. Add to this the fact that there is a code 41 listed on-line for the air mix door servo circuit and I am really confused.. I am NOT getting that code, but rather the more vague "Air outlet door" code 43.

The mode servo motor seems to be OK as I can switch modes and the air does change from defrost, vents, foot outlets, etc. I have seen writeups with pics for the GS and RX models, but none for the SC models. Anyone know how hard it is and how to get to the air mix servo in the SC?

Any help appreciated! Thanks

bugjug

code 41 is for the air mix damper, code 43 is for the air outlet damper.
the air outlet damper and servo motor control whether the air is directed to feet, face or both. It would not control the temp. You may have a bad air outlet sensor giving you a code 43, but the servosystem still working.

Sounds like you have an air mix servo system fault, regardless of whether you see code 41. The FSM has detailed troubleshooting info. If you don;t have one, search the forum for one. It will be very helpful. The servo motor is controlled by the climate control ECU (I believe), and it essentially reverses the polarity of voltage to the servomotor to control the position of the air flap between full head, full cold, or somewhere in between. If the servo sensor is hosed, the ECU may think it is fully to the cold position even if it isn't.
-bug

airtraffic

Thanks Bug,


I have not been able to find a FSM anywhere in the forums or otherwise.. Does anyone know how hard it is to get at the air mix servo? I'm thinking of starting there and replacing it since at around $140 it's the cheapest part. According to a diagram I saw on the forum, I think the air mix servo is on the driver's side of the car behind the heater core? Anyone been here?

bugjug

FSM is too large to email unfortunately, but I got mine from another very helpful forum member, brad11140. Maybe PM him?

I hope someone has removed this before because the FSM states to remove AC unit to get to it, and to remove AC unit it says to remove engine. This doesn't seem reasonable.

airtraffic

OK, this has gone in another direction.. Today I noticed a puddle of oil on the splash shield when looking from above. I know there are two aluminum A/C lines that run along the front of the car near the radiator. Turned out there is a leak in the smaller thinner line that runs through a clamp half way across the radiator. I added some refrigerant to see if the A/C would work. It does. (I also verified that the servos do in fact work.) So my problem is a small leak. I am trying to track down the part number for the line. It goes from the passenger side firewall to the front of the car, then accross the lower front area just behind the radiator, then ends near the compressor on the driver's side. I've seen it on the "lexusparts now" diagram, but cannot get a part number. I'm wondering how much it will ost to have the line replaced or if repair is possible? There is a substance that claims to be able to braze aluminum for just such a repair without taking it apart.. even with oil on the surface. Anyone deal with this line? Looks like it may have been clamped in there without a rubber grommet of any kind making chafing and cracking very possible on a 15 year old line.

1JZPWRD

iTrader: (59)

Should have read this sooner. I just cut the lines out of my 1993 to remove other things. Would have sold it cheap to you. Good luck with your search and repair.

bugjug

check the oil out to see what it is, might be P/S fluid? If it is compressor oil, you will need to replace it. I'd not run the compressor anymore til that is done.

good luck. sounds easier than pulling the engine

bugjug

can you post pics of this? I've also got a 95 sc400, and would like to avoid this becoming a future problem.
thanks.

airtraffic

It's definitely compressor oil.. I filled the system with a can of refrigerant and the A/C worked fine. I just don't know how fast it will leak down. I'll see if I can get a pic, but this is easy to find. Pull your splash shield and look under the radiator. You'll see two silver tubes along the bottom. One is a skinny tube and has a black clamp on it. That's the one that has the leak.