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Air conditioner pressure switch

Tiny
BLESSING EWOBOR
  • MEMBER
  • 2003 LEXUS RX 330
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 124,562 MILES
Hi, I am working with the vehicle listed above, its air conditioner is not working. The compressor is not responding to the switch. I have tested somethings like relay and fuse. I want to test the pressure switch, but it has four wires unlike the ones with two wires that one can easily by pass. In this case how will I test the switch or by pass the switch with four wires?
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Thursday, September 3rd, 2020 AT 4:58 AM

14 Replies

Tiny
ASEMASTER6371
  • MECHANIC
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Good afternoon,

Do you have a set of gauges to check the Freon pressure? That switch needs pressure to close to turn on the compressor.

I attached a wiring diagram for you to view. You will need a voltmeter to do some testing for the switches. There is a high side switch and low side switch in the same pressure sensor.

https://www.2carpros.com/articles/how-to-check-wiring

Roy
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Thursday, September 3rd, 2020 AT 12:50 PM
Tiny
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Thank you,

Sir, is that the full diagram? From the diagram you sent? It seems that something is missing in between for instance, for the second diagram, there's a yellow wire coming from the Diode(A/C)(behind upper left side of dash) did not reflect on first diagram and the wire numbering start from 6 at the extreme left on the second diagram. I can't find 2, 3, 4, 5 on the first.
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Thursday, September 3rd, 2020 AT 9:38 PM
Tiny
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Yes, it is. The first is the top of the diagram and the second is bottom of the diagram.

Print them out and put them together.

Roy
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Friday, September 4th, 2020 AT 3:52 AM
Tiny
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Thank you sir.
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Friday, September 4th, 2020 AT 7:34 AM
Tiny
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You are welcome.

Always glad to help.

Roy
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Friday, September 4th, 2020 AT 7:41 AM
Tiny
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Hi, from the article ""https://www.2carpros.com/articles/how-to-check-wiring", which talks about how wire can be checked and tested. The illustration used was camshaft position sensor and the engine ECU (both of them are in the engine compartment), the resistance on the wire between the sensor and the ECU was tested by connecting the meter, probe at both ends.
What if the engine ECU is in the vehicle (under the dashboard) how can the resistance of the wire between the sensor and the ECU be tested?
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Saturday, September 5th, 2020 AT 8:33 PM
Tiny
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You will need long cables to attach to each end. You can get a set of jumper wires at a parts store for this test.

Roy
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Sunday, September 6th, 2020 AT 4:04 AM
Tiny
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Lol, thank you.
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Sunday, September 6th, 2020 AT 7:43 AM
Tiny
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You are welcome.

Roy
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Sunday, September 6th, 2020 AT 7:55 AM
Tiny
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Good morning, please could you help me with diagram that will include " FAN 3 RELAY"? I want to use it.
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Monday, October 19th, 2020 AT 7:01 PM
Tiny
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From the diagram, For the A/C Triple pressure switch, the terminal that labelled 1, is it supposed to be five volts since it is coming from the engine control module?
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Monday, October 19th, 2020 AT 7:06 PM
Tiny
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Okay, I reattached the wiring diagram for you to view.

The pressure switch is 12 volts, not 5. Sensors have 5 volts and switches are 12 volts.

Check the fuse for relay number 5 in the diagram for power on both sides.

Roy
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Tuesday, October 20th, 2020 AT 1:28 AM
Tiny
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Thank you.
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Thursday, October 22nd, 2020 AT 9:43 AM

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