Heineken's Garage

Introduction
The Climate Control Unit (CCU) of the NSX controls heating, cooling and ventilation of the passenger cabin. It utilizes several electrical sensors and actuators across the vehicle to do so:

Sensors	Actuators
Outside temperature Cabin temperature Sunlight Heater core temperature Evaporator temperature	Blower Motor Mode control motor Vent door control motor Air mix control motor Recirculation control motor

Self Check
Except for the blower motor, above items can be checked by means of a CCU self check feature. It's activated by pressing both the left (Auto) and right (Off) button on the CCU at the same time. Each character on the display (except "FULL", AUTO" and the temperature value) represents a detected fault.

No errors dected

To ensure proper detection (especially for motor related issues) the CCU should be run in full automatic mode, then turn the temperature control from lowest to highest in slow steps. This makes the CCU run all actuators and confirm potential issues.

Indicator	Fault
MODE	Cabin temperature sensor - open/short circuit
	Outside temperature sensor - open/short circuit
	Sunlight sensor - open/short circuit
	Heater core temperature sensor - open/short circuit
	Evaporator temperature sensor - open/short circuit
A/C	Air mix control motor - open/short circuit or door stuck
ON	Mode control motor - mode door stuck or position signal circuit
OFF	Recirculation control motor - position signal circuit
-Button LED	Vent door control motor - open/short circuit or door stuck

Note that errors are not stored and will disappear upon ignition-off.


Auto Check Routine
An additional automatic check routine is available by setting the Fan-dial to "AUTO" and pressing both the Auto and mode button at the same time before switching on the ignition. Once activated the CCU is cycling through an combination of all settings which can be used to confirm that all of them are working as expected.

Temperature	Fan	Air Mix Door	Mode	Recirculate	A/C
88	off	full open		no	off
1	low	half closed		no	on
2	..	half closed		yes	on
3	..	full closed		yes	on
4	high	full closed		yes	on
5	high	half open		yes	on
6	..	half open		no	off
7	..	full open		no	off
8	low	full open		no	off
88	off	full open		no	off

This video shows the auto check routine in action: https://www.youtube.com/watch?v=c28_T5Ix_JY


Known Issues
Similar to many other ECUs in the NSX the CCU is subject to capacitor leakage and resulting damage. A typical symptom is a fan working on the highest setting only.
If these or other unusual effects are observed and/or the self check shows detected faults which can't be confirmed, action should be taken before the unit becomes irreparably damaged. Preventive replacement of the capacitors is highly recommended.