Do It Yourself? Is A NO NO NO
All repairs to HVAC equipment should be done by qualified technicians.
Do it yourselfers often make the situation worse and sometimes are seriously injured or even killed. Liquid refrigerants can cause frostbite and can blind you if you get it in your eyes. Inhalation of refrigerant vapors can cause respiratory problems or even death.
Some electrical components hold a charge even if the power has been disconnected. Most units operate on 230 or more volts, so there is a potential electrocution hazard.
You should be able to change or clean your own filters and wash off an outdoor coil (both actions are very important), but most repairs are not DIY. I have made quite a bit of money over the years correcting homeowner?s mistakes.
I am a retired HVAC technician, and currently teach refrigeration at a technical school.