sleven36

Hey guys im hoping that you can help me diagnose my air conditioning issues. Just bought this 94 LS a couple months ago. I love the car but the previous owner didnt take care of it at all so I have a lot of things to go through and fix. One of the main issues right now is the ac system is blowing hot. I live in the central valley of CA where the average temp has been in the high 90's lately so id really like to get this worked out. So the ac blows hot, doesnt get cold at all. The heat only works if you turn the temp all the way to max. Checked the freon level on the low pressure side with one of those home kits they sell at auto stores and it was in the blue so its full. I read that if the AC light blinks that your compressor is likely shot, thankfully mine does not blink. I checked the diagnostic codes and I am getting code 11 and code 33. On top of all that, when i pulled the stereo to check it out i found out that the previous owner had completely cut every single wire going to the hvac unit and had most of them on with crimps. I was absolutely shocked and frustrated that someone would do this. I went through and properly resoldered most of the wires back together however there are two wires left over that dont seem to go to anything. I dont know if this could be the source of my issue but Im thinking its not. I cant seem to find a wiring diagram to see where these wires go either. This is very frustrating and Im hoping you guys can help me. Sorry for the long read thanks in advance.

dicer

Check and make sure you can hand turn the compressor, of course with engine off.
As far as the wiring you will need a diagram to figure out where they all go. I agree very stupid for someone to mess them up since there are special adapter connectors to install after market head units.

sleven36

Do you mean I should release the tension on the drive belt and see if it will spin? Any idea where I can find a diagram I have searched a ton and cant find it anywhere.

dicer

No, just put your hand down there and turn it. There is a clutch that will allow it to turn by hand with the belt on and tight. If it won't turn it is seized and will need to be fixed. If it turns and you have a full charge then it could be the pressure switch, or the control or a valve or actuator. I'd need to hit the books on it to see how it is switched from heat to ac.

Are those the AC diagnostic codes?
11 is open or short in room temperature sensor.
33 abnormal operation of airmix servomotor or wire harness.

Fix those before jumping into something else.


Here is an electrical manual for 94
http://www.ebay.com/itm/1994-LEXUS-LS400-Electrical-Wiring-Diagram-Service-Manual-OEM-/201211274141?hash=item2ed920639d&vxp=mtrwhen its gone or link no good I'll delete it.

Also you can do this for the information.
https://techinfo.toyota.com/techInfo....toyota.com%2F

sleven36

dicer, thank you for the quick reply. I will try turning the compressor after work today. Also I plan on tracking down the cabin temp sensor and cleaning it or replacing it. Im not really sure where to even start with the code 33 problem. Im guessing it could be due to the wiring harness issue because my medium fan speed does not work at all. Thanks for the link, I think I might pick that book up.

dicer

That servomotor operates a flapper valve to direct either heat or cool, or mix them. I just saw a schematic of it, likely its in the heater/ ac box under the instrument panel assembly.

sleven36

The compressor wheel turns freely by hand so I guess that is not my problem and the system is full of freon. I am having trouble locating the cabin temp sensor, i can only find info on the 95 and up models. I will tear apart the panels under the steering wheel tomorrow and look for it. Is there any way to diagnose the servo motors without tearing the whole dash apart?

dicer

Yes there is a diagnostic mode that you can use and check them out.

sleven36

I have already pulled the diagnostics codes. I am showing code 11 and code 33. I am going to track down the interior temp sensor today however I remember reading that even if that sensor is not working the ac system should still come on on the coldest setting which mine does not. So j am not hopeful that will fix my problem. As for code 33 I'm not really sure what it means, are my servo motors that mix the air just not working? Could that be the reason it is just blowing hot air? I'm pretty sure my compressor is not even coming on when I turn on the ac.

aptoslexus

Lexus AC troubleshooting guide.

sleven36

Thank you for posting those diagrams, those are very helpful for showing me how the system works overall. Looking at this makes me realize that I need to know the exact pressures on the high and low pressure sides. I only know the low pressure side because I hooked up one of those DIY coolant tanks and it read in the blue. I do not have the tools to properly check the pressures so I will take it to a shop and have them do a check on it. Thank you

dicer

And all those show is the refrigerant system. On our LS's all that can be working fine and still not have cold air because there is a damper door that shifts from heat or ac if it will not move to ac then you will not have ac.