How to jumper A/C Pressure switch?

Tiny
JERRYCL
  • MEMBER
  • 2002 HYUNDAI ELANTRA
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 124,000 MILES
On a 2002 Elantra the A/C compressor clutch will not engage because of low R134a pressure. Went to jumper pressure switch to start charge but found 4 contacts rather than two. Which ones to jumper and not mess up? Diagram female socket please.
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Thursday, March 31st, 2011 AT 8:54 PM

7 Replies

Tiny
SATURNTECH9
  • EXPERT
I wouldn't disable the pressure switch while charging i would say that would be unsafe. So is the system empty? The charge just won't go in?

Here is a guide and some diagrams (below) of the ac pressure switch.

https://www.2carpros.com/articles/air-conditioner-how-to-add-freon

and

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

Please let us know what happens.

Cheers,
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Thursday, March 31st, 2011 AT 9:32 PM
Tiny
JERRYCL
  • MEMBER
Compressor clutch won't engage because the switch inactivates the clutch circuit. Will be charging on the low pressure side of the system, but nothing will happen until I cant get the compressor running.
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Thursday, March 31st, 2011 AT 10:46 PM
Tiny
SATURNTECH9
  • EXPERT
When the pressure increases from charging the compressor will kick on. Just open the gauge and let the system take in refrigerant and the system will kick on.

I would check for a leak as well.

https://www.2carpros.com/articles/air-conditioner-leak-detection

Cheers,
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Thursday, March 31st, 2011 AT 11:11 PM
Tiny
JERRYCL
  • MEMBER
System leaked to the point where the high pressure side is less than 29 psi. This opens the pressure switch and disconnects the clutch. To get the compressor going again, we have to energize the clutch by bypassing the pressure switch. Have done this before on other makes, but usually the pressure switch is a simple two lead situation. On the Elantra the Koreans have made it a four lead situation, and we are not sure which contacts to jumper.
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Friday, April 1st, 2011 AT 1:21 AM
Tiny
SATURNTECH9
  • EXPERT
There is no need to jump the pressure switch to do what your doing I have never had to do that for charging if its not charging then you have another issue. You will have no idea how much charge you already have in the system so it would be really easy to overcharge it and with the switch bypassed it could get ugly.
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Friday, April 1st, 2011 AT 4:42 PM
Tiny
JERRYCL
  • MEMBER
Was expecting you Hyundai mechanics would simply look up the wiring diagram [I don't have one] and tell me which socket contact points to use. This operation is like the original factory charge and repeated everytime a new commpressor is installed and system evacuated.
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Friday, April 1st, 2011 AT 4:47 PM
Tiny
KEN
  • ADMIN
Hey JERRYCL,

I found this wiring diagram for you so you can jump the pressure sensor.

Please let me know if you need anything else.

Best, Ken
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Wednesday, January 18th, 2017 AT 10:45 AM

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