Question about Dodge Ram 2500

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On the compressor cycle switch on the low side pressure of my a/c it has three wires.To make the compressor start which wires need to be jumped to make compressor run? it has low freon

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  • Mike Pierce Apr 29, 2010

    I know it is low

    so which wires do you jump to start compressor?

    so I can add oil and freon?

    There are three wires ?

    which one gets jumped?

  • Mike Pierce Apr 29, 2010

    2006 dodge ram 2500 diesel megacab

  • Mike Pierce Apr 29, 2010

    Yes they suppied better answers for my problem
    the person yesterday is the one that told me to jump the switch and as i told them that a mechanic said it could not be jumped
    so i guess i will have to pay somebody to add freon to my truck instead of adding it myself :(



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What year model, engine size? if you have low freon need to charge up switch is designed to cut out compressor so it doesnt get damaged from low refrigerant,as the oil is carried with refrigrant low freon means low oil traveling thu system

Posted on Apr 29, 2010

  • TripleTauto
    TripleTauto Apr 29, 2010

    you need to add freon. here is a diagram of the pressure switch.the switch controls a signal to the pcm. it is not really "jumpable" like old models you risk damaging pcm here is a description.....The A/C pressure transducer will change its internal resistance in response to the pressures it monitors. The powertrain control module (PCM) or the engine control module (ECM) (depending on engine application) provides a five volt reference signal and a sensor ground to the A/C pressure transducer, then monitors the output voltage of the transducer on a sensor return circuit to determine refrigerant pressure. The PCM/ECM is programmed to respond to this and other sensor inputs by controlling the operation of the A/C compressor clutch and the radiator cooling fan to help optimize A/C system performance and to protect the system components from damage. The PCM will disengage the A/C compressor clutch when high side pressure rises above 3172 kPa (460 psi) and re-engage the clutch when high side pressure drops below 1999 kPa (290 psi) . The A/C pressure transducer will also disengage the A/C compressor clutch if the high side pressure drops below 193 kPa (28 psi) and will re-engage the clutch when the high side pressure rises above 234 kPa (34 psi) . If the refrigerant pressure rises above 1655 kPa (240 psi) , the PCM will actuate the cooling fan. The A/C pressure transducer signal to the PCM/ECM will also prevent the A/C compressor clutch from engaging when ambient temperatures are below about 10°C (50°F) due to the pressure/ temperature relationship of the refrigerant. The A/C pressure transducer input to the PCM/ECM will also prevent the A/C compressor clutch from engaging when ambient temperatures are below about 10°C (50°F) due to the pressure/temperature relationship of the refrigerant.

  • TripleTauto
    TripleTauto Apr 29, 2010

    YOU should have r134a freon and you can add yourself once you hook can into low side it will allow enough in system to cut on but it is best to have gauges installed so you can see pressures.



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Location of the Ac low pressure switch 2007 Mkz

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There are a few reasons for the compressor not engaging. Lets start with the most common. low ac gas.A bad clutch on the compressor.Blown fuse.
Let is start with testing for low gas. (134a freon).Locate the dryer. this is on the passenger side of engine compartment. it looks like a tall cylinder, on the top side you will see a switch. unplug switch connector and jump the two terminals in connector with a piece of wire, this is the low pressure or cycling switch. you will be completing the circuit by jumping a wire across the terminals.If the compressor turns on when connectors are jumped then you are low on gas and the system needs recharging.
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I have a 1996 geo tracker I cant get the compressor to run I have relpaced the compressor relay which dosent help. freon is ok compressor cluch kicks in when direct wired.

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also does it run when u bypass/jump the compressor cycling switch? it is located in the low side of the sytem, thios is the line that is the larger of the two, hwere is the part # and picture.

1. compressure cutout switch (3 diff ones used)
FOUR SEASONS Part # 35756
Compressor Mounted Cut-Out Switch; 1 Term White
type two
FOUR SEASONS Part # 35973
Compressor Mounted Cut-Out Switch; 2 Term; Blue or Green; Low Pressure
type 3
FOUR SEASONS Part # 35970
Compressor Mounted Cut-Out Switch; 2 Term; Yellow

d2d2a20.jpgthis is type one and two, two wires.

next is type 3 one wire.
06d325f.jpg Next is the low side compressor cycling switch, most common problem.

ACDELCO Part # 155606 {#96069320}


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1 Answer

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control the compressor.

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