A/C Compressor does not turn on the fan comes on when the A/C button is on?

Tiny
BHAMDOC1973
  • MEMBER
  • 2009 MAZDA 3
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 91,000 MILES
Compressor does not come on the fan comes on when the A/C button is on. Compressor turns on by hand ac fuse in engine fuse box is good and has power. Checked gauges and the first picture is with engine on, ac on and knobs open on low/high sides but knobs closed at the gauge. Second picture is with knob open at low pressure side gauge cannot find any module for ac using a small auto or the auto pro, cannot see any ac modules or anything to do with HVAC. These are only codes it has. Car has few aftermarket stuff like a cold intake maybe but nothing else. I removed the relay and switched it with another same thing. I hear it click when it goes in. Which sides do I jump to see if it kicks on
Wednesday, August 13th, 2025 AT 9:45 AM

8 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
I have seen the sun load sensor cause this problem. I would replace it first and then clear the codes to see if the compressor kicks on. Clear the codes after the repair. Check out the images (below). Let us know how it goes.
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Wednesday, August 13th, 2025 AT 12:54 PM
Tiny
BHAMDOC1973
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  • 2,010 POSTS
Replaced it. But compressor still not coming on
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Monday, August 18th, 2025 AT 2:40 PM
Tiny
BHAMDOC1973
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Am gonna check the comressor wire. When I turn the car on and ac on should I get a ground and power on the 2 wires? Assuming there are only 3. If so and say I have it I want to jump the relay. Should I connect pin 87 to battery negative or positive to see if it turns.
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Monday, August 18th, 2025 AT 3:40 PM
Tiny
KEN L
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Did the code go away after you cleared it? Yes the red/yel wire at the compressor should get power, if so and the compressor is not working you have a bad compressor clutch coil. The AC MAG fuse and the control relay or in the fuse panel on the left side of the engine compartment. Here is the wiring diagrams so you can see how the system works. Check out the images (below). Please let us know what happens.
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Monday, August 18th, 2025 AT 7:17 PM
Tiny
BHAMDOC1973
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  • 2,010 POSTS
Does the car need to be running or just with ignition on?
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Monday, August 18th, 2025 AT 7:20 PM
Tiny
KEN L
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It need to be running with the AC system on cold max.
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Monday, August 18th, 2025 AT 7:25 PM
Tiny
BHAMDOC1973
  • MEMBER
  • 2,010 POSTS
I jacked up the car and found a one wire connector to the ac compressor. It is so tight to see or feel anything down there due to how the compressor is mounted. I noticed that the fog light was missing, so I thought maybe the previous owner hit something and caused damage. I found the wire cut from the compressor to the connector, hard to see but I felt it. So will jack it up more and try to reconnect it. Proble is I barely have enough length from the wire coming from behind the pulley but will see. Also found these 2 sensors disconnected and the connectors were tied in a zip tie. Car has some aftermarket stuff.
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Wednesday, August 20th, 2025 AT 5:21 AM
Tiny
KEN L
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Those look like impact or temperature sensors, but if you found bad wiring I would fix it first and then see if the compressor comes on.
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Wednesday, August 20th, 2025 AT 9:58 AM

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