2002 dodge caravan 3.3 w AC cluth not energizing, Low guage is 110 high is 75. 1. What wires can be jumped on the low pressure switch? to energize the AC clutch? I have low pressure and can not add freon. 2, any easy way to run 12vdc to the clutch diretly , can not reach wire bundle easy.

If you make a jumper wire, you can bypass the low pressure switch. This should energize the system

The system has to make the low pressure limit switch before it energizes the system. If you have 12v at the low pressure switch and verify that there is enough refrigerant in the system to make the switch, try jumping out the switch. If the compressor energizes the coil you are looking at a bad switch. If the compressor clutch does not energize I would look to the AC relay or maybe a bad switch at the control head.

IF the clutch is not engaging it may be due to the Freon being low. There is a low limit switch on the AC system. You can verify that by checking the pressure, or using a meter to check the clutch.

If low on gas, AC clutch will not be energized. Check for clutch operation by bypassing the low pressure cut off switch. If ac starts to run that is the problem. If it still does not energize then the clutch on AC compressor is bogus.

There are high and low pressure switches in the system to prevent the clutch from energizing if the system is low, or overcharged, or your cooling fans aren't coming on. You can jump your comp. just to verify that the clutch/coil is good to eliminate it as a problem. A/C button might be suspect, I doubt it. Ambient Air Temp Sensor (if equipped) could prevent clutch from engaging. Year, make, and model helps.

The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the powertrain control module (PCM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood accessory wiring junction block. The ground path is provided at G113. The relays are located in the underhood fuse / relay box .
So ,what's the problem Paul , car overheating ? Fans not working ?
During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the cooling fan 1 relay coil, closes the relay contacts, and supplies battery positive voltage from the cool fan 1 fuse through the cooling fan motor supply voltage circuit to the right cooling fan. The ground path for the right cooling fan is through the cooling fan 2 relay and the left cooling fan. The result is a series circuit with both fans running at low speed.
During high speed operation the PCM supplies the ground path for the cooling fan 1 relay through the low speed cooling fan relay control circuit. After a 3-second delay, the PCM supplies a ground path for the cooling fan 2 relay and the cooling fan 3 relay through the high speed cooling fan relay control circuit. This energizes the cooling fan 2 relay coil, closes the relay contacts, and provides a ground path for the right cooling fan. At the same time the cooling fan 3 relay coil is energized closing the relay contacts and provides battery positive voltage from the cool fan 2 fuse on the cooling fan motor supply voltage circuit to the left cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.
The PCM commands Low Speed Fans on under the following conditions:
?€¢
Engine coolant temperature exceeds approximately 106?°C (223?°F).

?€¢
When the A/C is requested and the ambient temperature is more than 50?°C (122?°F).

?€¢
A/C refrigerant pressure exceeds 1310 kPa (190 psi).

?€¢
After the vehicle is shut off if the engine coolant temperature at key-off is greater than 140?°C (284?°F) and system voltage is more than 12 volts. The fans will stay on for approximately 3 minutes.

The PCM commands High Speed Fans on under the following conditions:
?€¢
Engine coolant temperature reaches 110?°C (230?°F).

?€¢
A/C refrigerant pressure exceeds 1655 kPa (240 psi).

?€¢
When certain DTCs set.

So

Did you check the ac pressure? if too low or too high the unit will not come in. Be sure and check on the low side which should be around 35-50 psi. There is a high/low switch in the line which could also be malfunctioning.

The very 1st thing you do is see if the AC system has lost its charge of refrigerant. If the system is low on charge then the relay will not engage because it receives no signal from Compressor cycling switch which in most Fords is located in the low side AC line from the compressor, the low pressure line is the larger of the 2 lines from the AC compressor..

The low side pressure switch in the AC low pressure line signals the PCM (computer control) to close the AC compressor relay and raise the idle speed. If the system is low on refrigerant charge the relay will not allow the system to engage the compressor, this is because the oil that lubricates all the works is suspended in the AC refrigerant, if that is low then the system gets no lubrication and will quickly seize up..

"Most Fords have a CCRM (Continuous Control Relay Module) thats on the passenger side fenderwell. It has 4 relays: one for the AC compressor cluth, one for the fuel pump, and two for the electric fan (high- and low-speed.) The AC is the one that fails the most. You can replace the CCRM by removing the intake air filter box and working through the fenderwell openings. If it gets to difficult you must remove the wheel and splash cover to replace it from the wheel opening." - H-andy Mann

with the engine idling, tap on the ccrm and listen for the clutch to come on. if it comes on, you need to replace the entire ccrm.