1990 to 1996 Corvette HVAC Diagnostic Codes

C4 1990 to 1996 Corvette HVAC Diagnostic Codes Explained

1990 to 1996 Corvette models that are equipped with the C68 option code (Automatic, Electronic Air Condition) allow HVAC diagnostic codes to be read from the digital screen on the climate control panel. This feature is useful when attempting to diagnose issues with the A/C system. To learn more about entering the diagnostic mode and diagnostic code descriptions, read below.

DIAGNOSTIC MODE: ENTERED & EXPLAINED

To access the diagnostic mode, press and hold the climate control’s fan up and down arrow buttons at the same time until “-00” appears on the digital screen. Once the diagnostic mode is activated, the fan up and down buttons can be used to scroll through the various options. To view the value for a particular option, press the “AUTO” fan button.

1990 to 1996 Corvette HVAC Diagnostic Codes 2
Buttons on the climate control panel that are used while in diagnostic mode.

NOTE: If you see a “-” next to a value, for example “-105”, the neagtive sign must be removed and a value of 100 must be added to the orginal value to obtain the correct value for that option. Therefore, the correct reading for the example above would be 105+100 = 205.

HVAC DIAGNOSTIC CODES & DESCRIPTIONS

The crew at Corvette Salvage has compiled a list of the option values, option descriptions and code values/descriptions. You can view this list below. If you need further assistance, you can open a support ticket at anytime by clicking here.

Option Value Option Description HVAC Code / Code Description
0 System Faults (One of the following codes will be activated if the climate control has a flashing LED light.) 01 / Temperature Door Motor Circuit Fault
02 / Temperature Door Motor Circuit Fault
03 / Ambient Sensor Open
04 / Ambient Sensor Short
05 / In-Vehicle Temperature Sensor Open
06 / In-Vehicle Temperature Sensor Short
07 / Solar Load Sensor Open
08 / Solar Load Sensor Short
09 / Low Freon Detected
10 / UART Failure
1 Temperature Setting 60°F to 90°F
3 In-Vehicle Temperature Sensor 10 / Hot
-130=230 / Cold
4 Sun Load Sensor L98/LT4 Engine 38 / Maximum Light 183 / Maximum Darkness
LT5 Engine 115 / Maximum Light -110 = 210 / Maximum Darkness
5 Ignition System Voltage 0 / 9 Volts
-155 = 255 / 16 Volts
6 Engine Speed RPM divided by 25
7 Vehicle Speed
9 A/C System Mode 00 / Off
01 / Recirculation
02 / A/C
03 / Bi-Level
04 / Heater
06 / Defrost
07 / Vent
10 / Manual Recirculation
10 Blower PWM 0 / 0 Volts
128 / 14 Volts
11 Program Number 00 / Cold
-155 = 255 / Hot
12 Mix Number 00 / Cold
-155 = 255 / Cold
16 Coolant Temperature (°C) Coolant Temperature in degrees Celsius (°C)
17 Solar Correction 114 / Maximum Light
128 / Maximum Darkness
30 Stored Full Hot Value 0 to 50
31 Temperature Door Travel Range 100 to 200
34 Temperature Door Position Requested 00 / Full Hot
-153 = 253 / Full Cold
35 Compressor ON Time 0.1 Second Increments
36 Number of Times Below Critical Time Number of Times Below Critical Time
37 Software Version Software Version