How do I make the AC compressor turn on to fill the freon when it is empty?

Get a recharge kit from an auto parts store. There'll be a rubber line in the kit with a T-handle or a knob on it that must be turned out until the can lid piercing pin is up and clear of placing it on the can. Mount/push this connection onto the can but don't turn the handle in yet. Find the 2 caps on the AC lines and remove the smaller cap. It's black like the one on your tire fill. Only one of the fittings will fit the line. One is too large. The smaller one is the fill line fitting. Attach the rubber line to this fitting, start the engine and now pierce the can with the T-handle/knob so the compressor will suck the Freon into the system until the can is empty. You can use my trick of placing the Freon can in a container of hot water to be sure it empties completely. Now check to see is your AC working. Normally only 1 can will suffice to get the AC working. Too much Freon is just as bad as not enough. Remove the rubber line from the system after screwing the T-handle/ knob back into the canister to close it. Put the cap back on the line and your done. Open the canister back up with the end in a wet rag in case there's a little Freon left in the can, and dispose of the canister properly. Hide the rubber line somewhere for later use. You can purchase the Freon canisters singly now.

Low or no freon. Bad compressor. If its low, find the leak, repair, evacuate and recharge with oil and freon. CLEAN Freon. NOT a quick fill with sealant. That will do damage the system.

You can jump the compressor without having the key on. Run a jumper wire from the positive post of the battery to the single wire plug for the clutch. If it clicks, find an AC shop and have it checked for leaks and repair.

thats the reason why it wont come on because there is not enough pressure in the system for the compressor to cut in, recharge the system with freon and thats when the compressor will cycle

Below is a guide to troubleshoot and check system function. This can be done by most folks.

Look at the front of the ac compressor and have someone turn on the ac from inside the car. The front of the pulley(clutch) will spin when turned on.

If it does not spin, the low pressure switch (LPS) is not satisfied. Meaning there is not enough freon in the system to operate the system. Means low freon capicity because of a leak.

The LPS can be jumpered to cause the compressor to run (clutch to engaged) which will draw the freon in the system.

The LPS is usually a two wire sensor on the suction of the compressor. (between evaporator and compressor) Unplug the sensor and install a jumper, this will engage the clutch. Connect a new can of freon
and fill to system capacity.

The capacity of the ac system will be on a label under the hood, do not overfill. Probably about 2 lbs. Local parts stores (Auto Zone and Advance) will have freon with stop leak. This may help the leak. They also make a freon with a UV dye. I always add a single can with dye so that if stop leak does not work I can find the leak in the future.

The system should be filled until suction pressure is about 30 to 38 psi..

Remember the flow for the a/c system is :
1. From the compressor a high pressure (HP) gas goes to the condenser in front of the radiator.
2. From the condenser a HP liquid goes to an expansion device (orifice tube or expansion valve)
3. From expansion device the low pressure gas enters the firewall to the evaporator.
4. From evaporator the low pressure liquid/gas mixture goes through the dryer back to the compressor suction.

Look at the front of the ac compressor and have someone turn on the ac from inside the car. The front of the pulley(clutch) will spin when turned on.

If it does not spin, the low pressure switch (LPS) is not satisfied. Meaning there is not enough freon in the system to operate the system. Means low freon capicity because of a leak.

The LPS can be jumpered to cause the compressor to run (clutch to engaged) which will draw the freon in the system.

The LPS is usually a two wire sensor on the suction of the compressor. (between evaporator and compressor) Unplug the sensor and install a jumper, this will engage the clutch. Connect a new can of freon
and fill to system capacity.

The capacity of the ac system will be on a label under the hood, do not overfill. Probably about 2 lbs. Local parts stores (Auto Zone and Advance) will have freon with stop leak. This may help the leak. They also make a freon with a UV dye. I always add a single can with dye so that if stop leak does not work I can find the leak in the future.

The system should be filled until suction pressure is about 30 to 38 psi..

Check to see if A/C clutch is engaging. If it is not engaging, the compressor is not starting which will prevent the freon from being sucked into the system.

Look at the front of the ac compressor and have someone turn on the ac from inside the car. The front of the pulley(clutch) will spin when turned on.

If it does not spin, the low pressure switch (LPS) is not satisfied. Meaning there is not enough freon in the system to operate the system. Probably means a significant leak.

The LPS can be jumpered to cause the compressor to run (clutch to engaged) which will draw the freon in the system.

The LPS is usually a two wire sensor on the suction of the compressor. (between evaporator and compressor) Unplug the sensor and install a jumper, this will engage the clutch.

However, if it is empty the leak must be repaired.

The capacity of the ac system will be on a label under the hood, do not overfill. Probably about 2 lbs. Local parts stores (Auto Zone and Advance) will have freon with stop leak. This may help the leak. They also make a freon with a UV dye. I always add a single can with dye so that if stop leak does not work I can find the leak in the future.

The system should be filled until suction pressure is about 36 psi.

Does it have the correct amount of freon, it can still blow cold with the wrong amout of freon, this will damage the compressor,you may also have a bad cycling switch or bad high preasure switch and even a bad connection to ac system,this first thing is to make sure the correct amount was installed,

hi BE SHURE TO CHECK THE FREON GAS YOU ARE FILING IS COMPATIBLE WITH THE R12 IN THE SISTEM.THE R12 IS THE ORIGINAL FREON GAS THAT MODEL CAME WITH.IF THE AC SISTEM IS EMPTY THE AC COMPRESOR WILL NOT OPERATE UNTIL IT HAVES SOME GAS PRESURE SO WHEN YOU FILL THE SISTEM WITH THE FIRST BOTLE OF FREON IT WILL AUTOMATICALY START TO OPERATE ON AND OFF UNTILL THE SISTEM IS FULLY CHARGE

Look for the large ac line/hose coming out of the ac compressor,and follow that line until you come to a small ac port,this is the low side where you will hook up to to charge.I take it you have purchased a charge hose and freon?Put the can of 134a freon on the can tap at end of charge hose,and the quick connect will snap on the low side ac port on the vehicle.Turn the freon can upside down and turn the t handle on the can tap until it pierces the can.Start the vehicle,and set all settings high blower motor,max air,recirculate mode.The ac compressor should cycle on and off,this is normal,until there is enough freon in system.When the can starts to empty,shake the can lightly until empty.It will be hard to tell,but you will figure it out.Turn the can t-handle back out,and unscrew the can an repeat process until enough freon is in the system.You can get to much freon in the system.so see hoe much it takes to fill it on the label under the hood.If the system was not empty,it won`t take the fill amount,go slow,and feel the cold parts(large ac line near the firewall).They should get dern cool,to cold,and sweating really good.Stop when this happens,and it is cool inside.

freon is low. needs to be emptied. checked for leaks. fixed. refilled.
after it's filled they should check the pressures to make sure the compressor is ok.