A/C compressor clutch not engaging

Welcome to 2CarPros.

Can you tell me what the static pressure is? Also, under the hood is the power distribution box. These have been known to have problems. The A/C compressor relay is located there. Remove it, inspect the connections, and switch it with a relay with the same part number to see if that makes a difference.

In case you need it, here is a link that explains how to test a relay:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

I attached a portion of the wiring schematic for you to see what I am referring to. If this doesn't help, I will need to know if this has automatic or manual climate control.

Let me know.

Take care,
Joe

Welcome back:

Static pressure is the pressure in the system when it is off and hasn't been run for awhile. Both sides will be the same or extremely close. If you have gauges, let me know what it is. Also, if pressure is where it should be, then I am going to ask you to check the wire that runs to the compressor clutch to see if it gets power when you turn on the AC. The clutch could be bad, too. Another way to check the compressor clutch is to simply apply 12v to it. When you do that, it should click.

I have flow charts related to clutch not engaging and how to check the circuit. I am going to provide them. You're listed as a mechanic, so you should be fine with these.

Note: There are directions for both Manual AC and Automatic AC.

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I'm starting with the manual. The attached pictures basically the directions.

2006 Nissan-Datsun Truck Titan 2WD V8-5.6L (VK56DE)
Manual Air Conditioner
Vehicle Heating and Air Conditioning Compressor Clutch Testing and Inspection Component Tests and General Diagnostics Manual Air Conditioner
MANUAL AIR CONDITIONER
Magnet Clutch Circuit

SYMPTOM: Magnet clutch does not engage.

Inspection Flow
pic 1

INSPECTION FLOW

SYSTEM DESCRIPTION
The front air control controls compressor operation based on ambient and intake temperature and a signal from ECM.

Low Temperature Protection Control
The front air control will turn the compressor ON or OFF as determined by a signal detected by the intake sensor.

When intake air temperature is higher than the preset value, the compressor turns ON. The compressor turns OFF when intake air temperature is lower than the preset value.

Diagnostic Procedure For Magnet Clutch

Pic 2

Diagnostic Procedure For Magnet Clutch (Steps 1 - 2)

pic 3

Diagnostic Procedure For Magnet Clutch (Steps 3 - 6)

pic 4

Diagnostic Procedure For Magnet Clutch (Steps 7 - 9)

pic 5

Diagnostic Procedure For Magnet Clutch (Steps 10 - 12)

pic 6

DIAGNOSTIC PROCEDURE FOR MAGNET CLUTCH

SYMPTOM: Magnet clutch does not engage when A/C switch is ON.

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Here are the directions for automatic AC.

2006 Nissan-Datsun Truck Titan 2WD V8-5.6L (VK56DE)
Automatic Air Conditioner
Vehicle Heating and Air Conditioning Compressor Clutch Testing and Inspection Component Tests and General Diagnostics Automatic Air Conditioner
AUTOMATIC AIR CONDITIONER
Magnet Clutch Circuit

SYMPTOM: Magnet clutch does not engage.

Inspection Flow

pic 7

INSPECTION FLOW

SYSTEM DESCRIPTION
The front air control controls compressor operation based on ambient and intake temperature and a signal from ECM.

Pic 8

Low Temperature Protection Control
The front air control will turn the compressor ON or OFF as determined by a signal detected by the intake sensor and the ambient sensor.

When intake air temperature is higher than the preset value, the compressor turns ON. The compressor turns OFF when intake air temperature is lower than the preset value. That preset value is dependent on the ambient temperature, refer to the table.

Pic 9

Diagnostic Procedure For Magnet Clutch (Steps 1 - 2)

pic 10

Diagnostic Procedure For Magnet Clutch (Steps 3 - 6)

pic 11

Diagnostic Procedure For Magnet Clutch (Steps 7 - 9)

pic 12

Diagnostic Procedure For Magnet Clutch (Steps 10 - 12)

pic 13

Diagnostic Procedure For Magnet Clutch (Steps 13 - 17)

pic 14

Diagnostic Procedure For Magnet Clutch (Steps 18 -20)

pic 15

Diagnostic Procedure For Magnet Clutch (Steps 21 - 23)

pic 16

Diagnostic Procedure For Magnet Clutch (Steps 24 - 25)

pic 17

DIAGNOSTIC PROCEDURE FOR MAGNET CLUTCH

SYMPTOM: Magnet clutch does not engage when A/C switch is ON.

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Let me know if this helps or if you have other questions.

Take care,
Joe