Incorrect outside temperature reading

[CTScott]

Originally Posted by JudgeM

CTscott you are spot on. I disconnected the AC ecu and it read correctly !

So my question is now, can I just cut the thermistor wire that goes into the AC ECU and connect it to my meter instead ? I dont have the fancy climate control in my car, just the normal manual AC controls so I am thinking that the AC ecu doesn't really need to know the outside ambient temp.

The manual AC ECU does want the ambient temperature input as well. I believe it uses it to determine the duty cycle for the compressor to avoid freezing the evaporator when running it for defogging in colder temperatures.

You can try it though as see how the AC works. Another option would be to connect a fixed value resistor to the AC ECU pin and fool it with a constant outside temp value.