The Air Conditioning control function controls the compressor clutch, and the cooling of the condenser by use of the engine fan(s). There are two different control modes for use in situations where the factory air-conditioning control is present or removed.
The AC Clutch Control Runtimes can be monitored on the Misc tab of the Runtime Values window (F12 key).
AC Clutch Control Settings
This setting selects the operating mode of AC Clutch Control.
·OFF - AC Clutch Control is not used.
·Basic - When in Basic mode, if the ECU receives an AC Request it checks to see if the engine speed is above 400 RPM. If the engine speed is greater than 400 RPM it then turns on the outputs for AC Clutch and Engine Fan (setup to turn on with AC). The ECU will keep the AC Clutch and Engine Fan on until the AC Request turns off or the engine speed is under 400 RPM. The Basic mode is recommended for use with a system where a separate factory AC controller manages the AC Request signal.
Basic mode requires the following to work:
·Engine Speed > 400 RPM
·AC Request - Either a Digital Input channel or over CAN.
·AC Clutch - Auxiliary Output channel or control over CAN.
·Engine Fan - An Engine Fan set to be on with AC.
·Full - When in Full mode, if the ECU receives an AC Request it checks to see if the engine speed is above 400 RPM, the AC Evaporator Temp is above the Low Evap Temp Lockout, and the AC Pressure is between the High Pressure Lockout and the Low Pressure Lockout. If all of these conditions are met the ECU will then switch on the AC Clutch and the Engine Fan (setup to turn on with AC).
The ECU will keep the AC Clutch and Engine Fan on until one of the following:
·The AC Request turns off.
·The engine speed is under 400 RPM.
·The AC Evaporator Temp reaches the Low Evap Temp Lockout.
·The AC Pressure reaches the High Pressure Lockout.
·The AC Pressure reaches the Low Pressure Lockout.
The Full mode is recommended for use with a system where there is no factory AC controller, or when AC evaporator temperature control by the ECU is desired.
Full mode requires the following to work:
·Engine Speed > 400 RPM
·AC Request - Either a Digital Input channel or over CAN.
·AC Clutch - Auxiliary Output channel or control over CAN.
·Engine Fan - An Engine Fan set to be on with AC.
·AC Evaporator Temp - Either an AN Temp channel or over CAN.
·AC Pressure - Either an AN Volt channel or over CAN.
Note: If the AC system pressure reaches one of the pressure lockouts the ECU will turn off the AC Clutch and Engine Fan until a new AC Request is received.
Specifies the output being used to control the AC Clutch.
Select the input that the AC Request switch is wired to.
This setting can be used to disengage the AC compressor clutch when the engine is under high power.
·OFF - No condition to cause the compressor clutch to release
·TP(Main) - Throttle position condition. The condition suited for most setups.
·MAP - Manifold Pressure condition. For setups with no TPS.
·Inj DC - Injector Duty Cycle.
·AP(Main) - Accelerator Position condition. For E-throttle setups. This will disconnect the compressor clutch quicker than TP(Main)
The number that the compressor clutch will disengage at. The units of the number will depend on the setting selected for Clutch Off Runtime, for example TP(Main) will be %, MAP will be kPa.
This is the delay between AC request and engagement of the AC compressor clutch (and also disengagement). This delay allows time for the ECU to increase the amount of air bled into the engine via the idle speed control system to maintain a consistent idle.
The following setting are only available in 'Full' mode:
Select the input that the AC Pressure Sensor is wired to.
Select the AC Pressure Sensor Calibration.
The maximum pressure on the AC systems high side before the ECU will disconnect the compressor clutch. A typical value for this would be 2100 kPa, but this will vary from system to system. The High Pressure Lockout is designed to protect the AC system from damage if the pressure gets too high. The best way to find out the maximum pressure is to check the systems operating requirements from the service manual or using pressure gauges to measure operation on the factory(OEM) ECU.
The minimum pressure on the AC system's high side before the ECU will disconnect the compressor clutch. A typical value for this would be 175 kPa, but this will vary from system to system. The Low pressure Lockout is designed to protect the AC system from damage if the pressure gets too low.The best way to find out the minimum pressure is to check the systems operating requirements from the service manual or using pressure gauges to measure operation on the factory(OEM) ECU.
Select the input that the AC Evaporator Temperature Sensor is wired to.
Select the AC Evaporator Temperature Sensor Calibration.
The minimum temperature of the AC evaporator before the ECU will disconnect the compressor clutch. A typical value for this would be 3 or 4 degrees Celsius. This is the control that will cause the ECU to disconnect the compressor clutch in normal operation. If you do not want the ECU to turn off the AC system at a certain evaporator temperature set this lockout to the minimum (-10 °C or 14 °F), this will cause the Low Evap Temp Lockout to be ignored.