I advise against adding 134-a to a known leaking system without adding some dye to find and fix the leak. you lose lubricating oil along with the refrigerant and can seize the compressor which can send debris downstream necessitating the replacement of more components.
I haven't covered everything here so if you have anything you would like to add here please do so we can collaborate to possibly get a proper guide specific to our cars and sticky it.
keep in mind, that the post above Mine only covers a system that has gone to "0" psi or atmosphere, you must vacuum the system down in order to get refrigerant back into the system when it has gone that low on charge, doing this will bypass the "paperclip trick" by allowing enough refrigerant back into the system to let the ecu command the clutch on. If your system has gone this low you need to find the leak anyhow as you are just wasting the charge If you aren't trying to find the leak. ac dye can help here or take it to a shop to have them locate it and recharge it.
**Be careful shoving things into the pins as you can stretch them causing fitment issues that can lead to damage to the fuse center. the bad connection will heat up and melt the plastic parts**
there are many failure modes of an ac system that can lead to no clutch engagement.
1. electrical. fuse or relay, low or high pressure switch or the clutch itself
2. mechanical: all systems could be good but there can be an air gap in the clutch, you can carefully push the clutch to the pulley to see if it starts turning, there can also be a seized compressor
3, low pressure, check fittings on hoses for an oily film, it may be green tinged from a UV dye, look at the condenser for damage and the same oily green sludge, R134a has a distinct smell if you are trained to it, a larger leak can be noticed.
I haven't covered everything here so if you have anything you would like to add here please do so we can collaborate to possibly get a proper guide specific to our cars and sticky it.
keep in mind, that the post above Mine only covers a system that has gone to "0" psi or atmosphere, you must vacuum the system down in order to get refrigerant back into the system when it has gone that low on charge, doing this will bypass the "paperclip trick" by allowing enough refrigerant back into the system to let the ecu command the clutch on. If your system has gone this low you need to find the leak anyhow as you are just wasting the charge If you aren't trying to find the leak. ac dye can help here or take it to a shop to have them locate it and recharge it.
**Be careful shoving things into the pins as you can stretch them causing fitment issues that can lead to damage to the fuse center. the bad connection will heat up and melt the plastic parts**
there are many failure modes of an ac system that can lead to no clutch engagement.
1. electrical. fuse or relay, low or high pressure switch or the clutch itself
2. mechanical: all systems could be good but there can be an air gap in the clutch, you can carefully push the clutch to the pulley to see if it starts turning, there can also be a seized compressor
3, low pressure, check fittings on hoses for an oily film, it may be green tinged from a UV dye, look at the condenser for damage and the same oily green sludge, R134a has a distinct smell if you are trained to it, a larger leak can be noticed.