A/C clutch not to disengage from the compressor pulley

VJT_2006

MEMBER
2000 INFINITI QX60 HYBRID
3.3L
V6
4WD
AUTOMATIC
225,000 MILES

I replaced the old A/C compressor with new one due to noises on the old compressor pulley and clutch. The newly installed A/C compressor has been filled up with refrigerant and was in operation for more than 2 months before I noticed this problem.
When switching on the "Auto" button to activate the A/C, the A/C clutch
of the A/C compressor was continuously engaged with the compressor pulley even though the actual temperature inside the vehicle has reached its intended setting (already cold). What could be the problem that cause the A/C clutch not to disengage from the compressor pulley?

3 Replies

STEVE W.

MECHANIC
13,465 POSTS

That is normal operation in the auto mode. The system controls the interior temperature using both the A/C and the blend doors at the same time. In the Econ mode it should cycle the clutch on and off.

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Tuesday, July 27th, 2021 AT 5:22 AM

VJT_2006

MEMBER
2 POSTS

Dear Steve,

Thank you for the info. However, when I did the actual test on the Econ mode the A/C clutch didn't turn on and off or cycled. When I refer to the manual operation, it says that the Econ mode is used for heat only. Also, I just want to know if the normal operation of the dual pressure switch is shorted when the engine is off.
Best Regards,
Vicente Jr Tuazon
Canada

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Tuesday, July 27th, 2021 AT 6:13 PM

STEVE W.

MECHANIC
13,465 POSTS

Econ mode should cycle the compressor as well as the heat unless the OE service information is wrong. The Canada and US spec both show ECON as cycling the compressor while the auto mode controls everything including the vents but keeps the AC compressor engaged and sort of fights the heat and AC together to maintain the temperature, if it gets warm the blend doors more to the AC side, if it gets to cold the doors open to the heater core side. The pressure switch should be closed unless it sees a higher or lower pressure than normal, then it opens. Attached is the schematic showing the switch in the first image, the other three are the controls for the rest of the system.

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