use2windsurf

87 NA 944

Does anyone have a schematic of the AC control panel? I am having to overhaul my whole AC system and I am trying to dumb down the temperature control. I just want to use the temperature control to adjust the temp by feel and not by using all of the temperature sensors (which are all missing or broken in my car). Also does anyone have a write up that shows how the controller uses the 3 temp sensor inputs ?

Another question: Without AC and the recycle/circulation vents closed and temp set to minimum, I read about a 7 degree F difference between the temperature in the cabin and the air temp coming from the vents.. That seems high to me. when I dial the temp to heat, I get blasted with hot air, so I know the flaps are working. Maybe when set to cool mode the flap isn't closed all the way? that is one reason why I wanted to know how the temp sensors are used for control. - Thanks

dave1192

Well ... I've spent some time studying it and guessing about how it works. I even made up an initial diagram for myself, but it isn't really all that good. In my case, I think the cabin temp sensor is bad, but haven't wanted to go into the dash to try to fix it. My AC is low on charge anyway, so that doesn't work.

Here is my diagram, for what it may or may not be worth. I'd be very interested in seeing what you come up with in your reverse engineering.

use2windsurf

I dont see your attachment on my ipad. I'll check for it on my pc in the morning. I found a post that describes the sensor restance values for the three temp sensors. I found a NTC thermistor at Digikey that has specs very close to the OEM. these parts are $0.39 each and we should be able to remove the existing ones and solder in place on the current assemblies. I am ordering some tomorrow, I have multiple problems including bad valves that control the recirc flaps, heater control valve, and external temp sensor on the left side blower motor motor intake. I live in Alabama, its hot and humid and I will get to the bottom of this if it kills me, and it might.,,,

william_b_noble

the cabin sensor on my car at least has a small fan to suck air over it - the fan can stop running and then the sensor doesn't sense much. the fan is on the firewall behind the glove box

John_AZ

dave1192,

Thanks, excellent info in PDF

J_AZ

944Ross

I've heard about the interior temp sensor before, but the FSM refers to 3 sensors... appears they are all identical. I'd be interested to know the Digikey p/n's for future reference.

use2windsurf

Vishay P/N NTCLE1003103JB0
Digikey p/n: BC2301-ND

resistance specs are pretty close, should be good enough.

Hans

THX!