Air Conditioning Diagnostics

Nissan R32 Skyline AC Diagnostics

Models: GTR, GTST, GTS, GTS4, Other
Website Category: Guide

If you are having issues with your air conditioning or just want to check the general status of the system, this guide will allow you to perform a full diagnostic.

Step 1: LED Segment Display Check
To start the diagnostics, hold the OFF button on the air conditioning control panel and then turn key in the ignition from off to on. Wait for about 8-10 seconds until you see the LED screen on the control panel display all segments all at once. This is the first of 5 steps within the diagnostics. This step allows you to make sure the screen is functioning properly and that all the segments are working.

Step 2: System Sensors Check
The next step is intended to check all the sensors in the system. Press the hot button (red arrow up) one time to move on to this step. You can hit the cold button (blue arrow down) as a back button to go back a step.

Once you have hit the hot button, a number will appear. A solid 20 means everything is normal with nothing wrong. However if you see a flashing number (or multiple numbers), this means there is an issue. Additionally, if there is a negative in front of the number, this means the sensor is either disconnected or shorted.

Here are all the possible error codes:
21 – Issue with outside air sensor
22 – Issue with inside air sensor
23 – Issue with water temperature sensor
24 – Issue with intake temperature sensor
25 – Issue with sunshine UV sensor (NOTE: This is common if you are doing this diagnostics in a shop or garage – drive into a sunny area to see if issue still persists)
26 – Issue with PBR (Potentio-Ballast-Resistor)
27 – Issue with refrigerant temperature sensor

Step 3: Mode door position check
Hit the hot button again to get to step 3. This step is intended to check the different modes that are normally selected by pressing the Mode button on the AC controls. Specifically, the mode door actuator operation. The first thing you will see is a solid 3. It is at this point you will hear some noises as the actuators go through there diagnostics. Wait about 15 seconds until you see the 3 become 30 (if everything is good). If you stay in this step, the diagnostics will continue again.

If there is a number (or multiple numbers) flashing, this indicates an issue. The codes are:
31 – Vent issue
32 – B/L issue
34 – Foot issue
35 – D/F issue
36 – Def issue
31, 32, 34, 35, 36 pattern is displayed – Connector disconnection indicated

Step 4: Actuator Operation Check
Hitting the hot button again will bring you into a mode that lets you check the air door motors. Each one is represented by a number ranging 41-47, with each one being checked by hitting the AMB button. This does not necessarily tell you something is wrong, but instead lets you check that all these are working in general.

Step 5: Temperature Sensors
Pressing the hot button will bring you to the next step with a 5 being displayed on the LED screen. This step will show you all the sensor readings. These include (in order): Outside air sensor temp located on the front of the fan out front (which is your exterior ambient temperature sensor), Inside air sensor temp located next to ash tray, Suction sensor temp located inside the evaporator core , and Refrigerant sensor temp also located inside the evaporator. Pressing the AMB button allows you to get the readings of each in Celsius in the above order. If all the temps are positive, this typically indicates all the sensors are good. However if temp reading is negative, this means the sensor is bad or disconnected.

Step 6 (Optional): Setting Difference Options
Lastly, press the Fan button on the control panel while in step 5 to move to step 6. Hitting the fan button again will move you back to step 5. This last step is optional and used to adjust 2 settings. The first being if you feel that the temperature differs from the temp on the display temp, you can make adjustments to the auto sensing temp. To do this, you can hit the hot or cold button, which will adjust the temp buy half a degree in Celsius.

To exit the AC diagnostics turn the key in the ignition to off

The above is intended to be a high level overview of the AC diagnostics. If you want to dive deeper and do more in-depth trouble shooting, see the FSM (Factory Service Manual), under section “H1 Air Conditioner”.


See something wrong or missing? Let us know

If you found this page helpful, consider supporting us by linking to this page or to R32 Skylines Website

We need your help

Help fellow R32 Skyline owners by contributing your knowledge, photos, or docs. We welcome any edits or additions.