360 A/C Recharge - won't take freon.

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https://www.ferrarichat.com/forum/threads/360-ac-problem-high-low-side-low-high-side.625819/

 

First off check that the condenser fan is cutting in. The compressor is working otherwise you would have no diff in suct and discharge pressure. Expansion valve is working otherwise you would have very low suct pressure.
When you are adding freon do you have to short out the LP switch at the drier ? Your readings make me ask if u have too much gas in system ?

 

Low side should be about 45 psi.

 

Forgive my ignorance but if low/high side are ~ same pressure, how do you get expansion to create cooling?

Also, don’t AC chargers (Autozone type) have a colored gauge....yellow low charge, green Ok, red high....the green mid point is about 45 psi.

 

You will get equal pressures when the system is off, ie the compressor not running. With the ac off the high and low pressures will equalize in the pipework. When the compressor starts it reduces the suction side and the discharge pressure increases. When the compressor is running, it supplies high pressure gas to the condenser, where it is condensed to a liquid at the same pressure . This high pressure liquid is supplied to the expansion valve where it expands to a chilled gas at a lower pressure. ie the suction pressure at the compressor. Think of the expansion valve like a CO2 fire extinguisher discharging its white gas.

 

Thank you. Good explanation.

 

I am no expert but the compressing a gas will cause a phase change to liquid and add heat. I thought that the liquid goes to the condenser and is cooled, then expands. Either way, the net effect is the same. Expansion absorbs energy so it cools.

 

The compressor will compress gas, which adds heat due to the compression process. You then remove the heat in the condenser where the gas changes state to a high pressure liquid. You then pass the hp liquid through the expansion valve where it changes state to a low pressure gas, dropping it temp in the process. Think of a CO2 fire extinguisher. HP is the pressure in the cylinder and LP is the atmospheric pressure it discharges into.

 

Check that the low pressure switch at the filter drier is operating correctly. If it thinks the system has lack of gas it will stop the compressor cutting in. You might have to bypass it to charge the system. Only 2 wires so either short them or open circuit.

 

Let's be really clear about something.....if the clutch is not engaged the system is not working. There is no way to tell how much freon is in the system because if the clutch does not engage......the static pressure (off) is completely irrelevant.

As to why your clutch does not engage....it is likely an electrical issue with a fuse, pressure switch or a wire. At this point, I would be concerned you are doing more harm than good since you really don't have the tools/knowledge to diagnose the issue. Why don't you take it to a shop that can properly evacuate the system and reload it? They have the equipment to check for leaks which will be a lot cheaper than rebuilding a compressor which may not need rebuilding. They can quickly determine the root cause.

It is your car and your choice. I am HVAC licensed from Commercial, Automotive and Residential and more automotive compressors have died from Autozone overcharging than any other cause.