Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSINFINITI2002Q45 V8-4.5L (VK45DE)REPAIR AND DIAGNOSISRELAYS AND MODULESRELAYS AND MODULES - HVACCONTROL MODULE HVACTESTING AND INSPECTIONINITIAL INSPECTION AND DIAGNOSTIC OVERVIEW
2002 Infiniti Q45 V8-4.5L (VK45DE)
Initial Inspection and Diagnostic Overview
2002 Infiniti Q45 V8-4.5L (VK45DE)SECTION Initial Inspection and Diagnostic Overview
TROUBLE DIAGNOSIS PROCEDURE FOR A/C SYSTEM
SYMPTOM:
* A/C system does not come on.
MAIN POWER SUPPLY AND GROUND CIRCUIT CHECK
Component Descriptions
Automatic Amplifier (Auto Amp.)
The auto amplifier has a built-in microcomputer which processes information sent from various sensors needed for air conditioner operation. The air mix door motor, mode door motor, intake door motor, blower motor and compressor are then controlled.
The auto amplifier is unitized with control mechanisms. When the various switches and temperature adjustment dial are operated, data is input to the auto amp from the display (and NAVI) control unit using multiplex communication.
Self-diagnostic functions are also built into auto amplifier to provide quick check of malfunctions in the auto air conditioner system.
Potentio Temperature Control (PTC)
The PTC is built into the Display (and NAVI) control unit. It can be set at an interval of 0.5 °C (1.0 °F) in the 18 °C (60 °F) to 32 °C (90 °F) temperature range by turning the temperature dial. The set temperature is displayed.
DIAGNOSTIC PROCEDURE
SYMPTOM:
* A/C system does not come on.
A/C System (Main Power Supply and Ground Circuit Check) - Inspection Flow:
SYMPTOM:
* A/C system does not come on.
MAIN POWER SUPPLY AND GROUND CIRCUIT CHECK
Component Descriptions
Automatic Amplifier (Auto Amp.)
The auto amplifier has a built-in microcomputer which processes information sent from various sensors needed for air conditioner operation. The air mix door motor, mode door motor, intake door motor, blower motor and compressor are then controlled.
The auto amplifier is unitized with control mechanisms. When the various switches and temperature adjustment dial are operated, data is input to the auto amp from the display (and NAVI) control unit using multiplex communication.
Self-diagnostic functions are also built into auto amplifier to provide quick check of malfunctions in the auto air conditioner system.
Potentio Temperature Control (PTC)
The PTC is built into the Display (and NAVI) control unit. It can be set at an interval of 0.5 °C (1.0 °F) in the 18 °C (60 °F) to 32 °C (90 °F) temperature range by turning the temperature dial. The set temperature is displayed.
Diagnostic Procedure / Nos. 1 - 2:
DIAGNOSTIC PROCEDURE
SYMPTOM:
* A/C system does not come on.
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.