* Sufficient system pressure: Low refrigerant can indeed *indirectly* prevent the compressor from engaging because the low-pressure switch will cut power to the compressor clutch to prevent damage. This is a safety feature.
* Proper electrical connection: Make sure all wiring and connections to the compressor clutch, the low-pressure switch, and the cycling switch (if equipped) are clean, tight, and undamaged.
* Working compressor clutch: The compressor clutch itself might be faulty, even independent of the freon level. It's a magnetic clutch, and failure could be due to a bad coil, seized bearings within the clutch, or other mechanical issues.
* Compressor itself: The compressor could have a seized internal component. This is less likely if the system has just run out of refrigerant, but is possible if there's been a significant failure (like a catastrophic leak).
Therefore, adding freon alone probably won't start your 1987 Pontiac 6000 AC compressor if the problem isn't just low refrigerant. Here's what you should do:
1. Check the low-pressure switch: This switch is usually located near the evaporator (inside the car) and is a safety device. If the pressure is too low, the switch will cut power to the compressor clutch. You'll likely need a manifold gauge set to check the system pressure.
2. Check the system for leaks: Before adding any refrigerant, you *must* find and fix any leaks. Adding freon to a leaking system is wasteful, expensive, and harms the environment. A qualified technician can use leak detection dye or an electronic leak detector to find leaks.
3. Inspect the compressor clutch: Visually inspect the clutch for any obvious damage. You can try to manually engage the clutch (be careful!), but a seized clutch often requires replacement.
4. Check the electrical components: Inspect all wiring to the compressor and related switches. A multimeter can check the voltage at the clutch. A qualified mechanic can test the switches and related components.
5. Add refrigerant (only after confirming no leaks): Once you've ruled out other issues, then you can add refrigerant, but *only after having checked for and repaired any leaks.* You'll need a proper refrigerant charging kit with gauges. Improper charging can damage the system.
Recommendation: Because finding and fixing AC issues can be complex and requires specialized tools, this is best left to a qualified automotive air conditioning technician. Attempting to repair the system yourself without the proper knowledge and equipment could lead to further damage and more expensive repairs. The cost of a proper diagnosis and repair is likely far less than the potential damage you could cause.
