Aircon temperature control
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Hi guys, can you please look at the viability of adding an extra logic item on the aircon controls. On the OEM Nissan ECU's I've dealt with, there are inputs into the ECU from the aircon evaporator that can either be an NTC thermistor (tested and works with an AN Temp channel) or a 12V/NC switch, depending on the model. What would be good to see is the aircon logic having the option to trigger off an AN Temp channel, with hysteresis, or trigger off a DI channel with a selectable ON level.
I've tried wiring the 12V/NC switch into the existing Aircon Request DI, but as this DI needs to have its pull-up resistor on, go through a pressure switch on the aircon receiver/dryer and then earth through the button on the dash, I can't get it to apply the required logic.
If you have the inputs free you could add in the additional input and then use a virtual aux with the extra conditions.
Hey Simon, yeah that is the setup I am currently running:
Virtual Aux 2 = Aircon Clutch (also drives dedicated fast-idle solenoid, so idle Aircon step table is zeroed)
DI6 = GP Input, connected to thermistor 12V/NC output
GP Output 8 conditions = Virtual Aux 2 AND DI6.
The problem with this setup is that when VA2 is active and DI6 is inactive, the aircon compressor clutch & idle-up solenoid are off but the Aircon fan is on. With no ability to idle compensate for the aircon fan alone (like there is for Engine fan), idle quality is very poor and the car is easy to stall. And since this happens based on the thermistor's input, it's not something that can easily be predicted or compensated for in another way.
So another solution for cars running the thermistor with the 12V/NC output is to just add in an Aircon fan idle step, or make the Engine fan step also apply to the Aircon fan output. This doesn't address the cars with just a direct NTC thermistor that requires wiring to an AN channel.
