STEVE BURNS
Club Member
300ZX Info - Auto Air Conditioner
The 300ZX has ( can have ) an automatic air conditioner. It's quite a clever system that monitors the outside temperature, the sun load ( how bright it is ) and the high / low ( foot ) area temperatures inside the car, trying to keep them at the set levels.
There is some work you can easily do on the system yourself, without even opening the bonnet using the self-diagnostic system. Armed with this info you can give hints to Nissan which bits YOU want changed not THEM. The following should be interesting to most 300ZX owners as you don't even have to get your hands dirty!
* Putting the system into Self-diagnosic mode
* Checking the readings from the Sensors
* Changing the Upper/Lower temperature levels
Auto Air Conditioner - Setting Self-diagnosic mode
1. Lets assume that something lights up on the Air-Con display. If it doesn't then it's faulty wiring or the unit itself. Best you check the wiring for power ( you have got the ignition on haven't you ? ) before going to your Nissan parts supplier.
2. Put the system in self-diagnosic mode. With the engine running and the Air-Con OFF hold down OFF while pressing the AUTO switch for at least 5 seconds.
3. Check that the Air-Con comes on and SET "00" appears. If not it's more than likely a fault with the OFF or AUTO switch.
You're now in self-diagnosic mode. To exit just press OFF or switch the ignition off.
Auto Air Conditioner - Checking the sensors
There are a number of temperature sensors that send info to the control unit
* Ambient temperature sensor
* In-vehicle sensor (Upper area)
* In-vehicle sensor (Lower area)
* Duct sensor (Defroster)
* Duct sensor (Ventilator)
* Duct sensor (Floor)
* Sunload sensor
* Water temperature
One of the most useful things you can do is check the readings that these sensors are giving. If the Air-Con system is acting oddly it's more than likely one of the sensors giving odd readings. The readings given are quite interesting anyway but don't have a crash doing this while blasting down the road...
1. Put the system in self-diagnosic mode.
2. You're now on in the sensor monitor mode. The SET display shows the item you're looking at while the AMB display shows the value. To move between the codes use the HI or LO switch.The codes / possible values are :-
Sensor Monitor Code Item Range
00 Ambient temperature -30 to 45°C (-22 to 113°F)
01 Upper compartment temperature 18 to 30°C (64 to 86°F)
02 Lower compartment temperature 20 to 35°C (68 to 95°F)
03 Defrost outlet air temperature 5 to 70°C (41 to 158°F)
04 Vent outlet air temperature 5 to 40°C (41 to 104°F)
05 Floor outlet air temperature 20 to 70°C (68 to 158°F)
06 Sunload 0 to 900 kcal/h (see note 1)
07 Water temperature 20°C (68°F) or 80°C (176°F) (see note 2)
08 MODE door voltage 0 to 5 volts
09 Internal data Anyone know?
NOTE 1: The shown figure is one tenth of the kcal/h value.
NOTE 2: If the coolant temperature is below 40°C then 20°C is show else 80°C is shown
If any of the values vary greatly from the real value then the sensor may be faulty. The Air-Con control unit actually keeps track of faults on these sensors and store the data. This is how to view this data :-
1. Put the Air-Con in self-diagnosic mode. Note :You can do this from the step above.
2. Press AUTO until the SET display reads "50" ( should be 3 presses ). This is the Trouble data memory readout system.
3. Use the HI and LO switches to move through the error readout data. The AMB display shows "50" if there are no problems with this item, "49" to "01" a problem existed and this is the number of engine start/stops since the problem started and "0" the problem exists now.
4. On the third digit of the AMD display a vertical bar in the top righthand corner shows a sensor open circuit and a horizontal middle bar a short circuit.
Sensor Memory Codes Code Sensor Open Circuit Short Circuit
50 Ambient sensor Less than -70°C (-94°F) Greater than 141°C (286°F)
51 Upper compartment sensor Less than -38°C (-36°F) Greater than 141°C (286°F)
52 Lower compartment sensor Less than -38°C (-36°F) Greater than 141°C (286°F)
53 Defrost outlet air sensor Less than -38°C (-36°F) Greater than 141°C (286°F)
54 Vent outlet air sensor Less than -38°C (-36°F) Greater than 141°C (286°F)
55 Floor outlet air sensor Less than -38°C (-36°F) Greater than 141°C (286°F)
56 Sunload sensor Cannot detect this Greater than 1,534 kcal/h
By this point you should have a good idea of whats going on....
Auto Air Conditioner - Changing the Upper / Lower temperatures
It's possible to set the difference between the upper and lower compartment target temperatures. This can be good if you tend to get cold feet in the car for example. Although the range of change may not seem much it's usually enought to make the required effect
1. Put the Air-Con in self-diagnosic mode.
2. Press AUTO until the SET display reads "40" ( should be 2 presses ).
3. Use the HI and LO switches to move through values -20 to 20 for °C and -32 to 32 for °F. This number ( displayed in AMD ) is the difference between the Upper and Lower target temperatures DIVIDED BY 10. So the max change is +2°C to -2°C.
This stays set until either the next change is done or the power is removed ( e.g. battery removed ).
The 300ZX has ( can have ) an automatic air conditioner. It's quite a clever system that monitors the outside temperature, the sun load ( how bright it is ) and the high / low ( foot ) area temperatures inside the car, trying to keep them at the set levels.
There is some work you can easily do on the system yourself, without even opening the bonnet using the self-diagnostic system. Armed with this info you can give hints to Nissan which bits YOU want changed not THEM. The following should be interesting to most 300ZX owners as you don't even have to get your hands dirty!
* Putting the system into Self-diagnosic mode
* Checking the readings from the Sensors
* Changing the Upper/Lower temperature levels
Auto Air Conditioner - Setting Self-diagnosic mode
1. Lets assume that something lights up on the Air-Con display. If it doesn't then it's faulty wiring or the unit itself. Best you check the wiring for power ( you have got the ignition on haven't you ? ) before going to your Nissan parts supplier.
2. Put the system in self-diagnosic mode. With the engine running and the Air-Con OFF hold down OFF while pressing the AUTO switch for at least 5 seconds.
3. Check that the Air-Con comes on and SET "00" appears. If not it's more than likely a fault with the OFF or AUTO switch.
You're now in self-diagnosic mode. To exit just press OFF or switch the ignition off.
Auto Air Conditioner - Checking the sensors
There are a number of temperature sensors that send info to the control unit
* Ambient temperature sensor
* In-vehicle sensor (Upper area)
* In-vehicle sensor (Lower area)
* Duct sensor (Defroster)
* Duct sensor (Ventilator)
* Duct sensor (Floor)
* Sunload sensor
* Water temperature
One of the most useful things you can do is check the readings that these sensors are giving. If the Air-Con system is acting oddly it's more than likely one of the sensors giving odd readings. The readings given are quite interesting anyway but don't have a crash doing this while blasting down the road...
1. Put the system in self-diagnosic mode.
2. You're now on in the sensor monitor mode. The SET display shows the item you're looking at while the AMB display shows the value. To move between the codes use the HI or LO switch.The codes / possible values are :-
Sensor Monitor Code Item Range
00 Ambient temperature -30 to 45°C (-22 to 113°F)
01 Upper compartment temperature 18 to 30°C (64 to 86°F)
02 Lower compartment temperature 20 to 35°C (68 to 95°F)
03 Defrost outlet air temperature 5 to 70°C (41 to 158°F)
04 Vent outlet air temperature 5 to 40°C (41 to 104°F)
05 Floor outlet air temperature 20 to 70°C (68 to 158°F)
06 Sunload 0 to 900 kcal/h (see note 1)
07 Water temperature 20°C (68°F) or 80°C (176°F) (see note 2)
08 MODE door voltage 0 to 5 volts
09 Internal data Anyone know?
NOTE 1: The shown figure is one tenth of the kcal/h value.
NOTE 2: If the coolant temperature is below 40°C then 20°C is show else 80°C is shown
If any of the values vary greatly from the real value then the sensor may be faulty. The Air-Con control unit actually keeps track of faults on these sensors and store the data. This is how to view this data :-
1. Put the Air-Con in self-diagnosic mode. Note :You can do this from the step above.
2. Press AUTO until the SET display reads "50" ( should be 3 presses ). This is the Trouble data memory readout system.
3. Use the HI and LO switches to move through the error readout data. The AMB display shows "50" if there are no problems with this item, "49" to "01" a problem existed and this is the number of engine start/stops since the problem started and "0" the problem exists now.
4. On the third digit of the AMD display a vertical bar in the top righthand corner shows a sensor open circuit and a horizontal middle bar a short circuit.
Sensor Memory Codes Code Sensor Open Circuit Short Circuit
50 Ambient sensor Less than -70°C (-94°F) Greater than 141°C (286°F)
51 Upper compartment sensor Less than -38°C (-36°F) Greater than 141°C (286°F)
52 Lower compartment sensor Less than -38°C (-36°F) Greater than 141°C (286°F)
53 Defrost outlet air sensor Less than -38°C (-36°F) Greater than 141°C (286°F)
54 Vent outlet air sensor Less than -38°C (-36°F) Greater than 141°C (286°F)
55 Floor outlet air sensor Less than -38°C (-36°F) Greater than 141°C (286°F)
56 Sunload sensor Cannot detect this Greater than 1,534 kcal/h
By this point you should have a good idea of whats going on....
Auto Air Conditioner - Changing the Upper / Lower temperatures
It's possible to set the difference between the upper and lower compartment target temperatures. This can be good if you tend to get cold feet in the car for example. Although the range of change may not seem much it's usually enought to make the required effect
1. Put the Air-Con in self-diagnosic mode.
2. Press AUTO until the SET display reads "40" ( should be 2 presses ).
3. Use the HI and LO switches to move through values -20 to 20 for °C and -32 to 32 for °F. This number ( displayed in AMD ) is the difference between the Upper and Lower target temperatures DIVIDED BY 10. So the max change is +2°C to -2°C.
This stays set until either the next change is done or the power is removed ( e.g. battery removed ).