No.
No
Is r-22 Freon compatible with r-134a freon?
Not unless you like the idea of destroying your AC system.
R-421A is an R22 alternative refrigerant. It is licensed under the Choice brand name ( Choice R-421A). It is a blend of 58%/42% R-125 and R-134a. It is a non-ozone depleting refrigerant, and the only 2-component refrigerant blend to replace R22. For more information, visit www.rmsgas.com.
Not without conversion.
No.
No, you should not mix R-134a with an R-22 system. R-22 and R-134a are different refrigerants with distinct properties and are not compatible. Using R-134a in an R-22 system can lead to system inefficiency, potential damage, and could violate environmental regulations. If you need to switch refrigerants, it's best to properly reclaim the existing R-22 and retrofit the system for R-134a or another compatible refrigerant.
Not without conversion.
Your AC won't work any better than it did before. Two very different refrigerants, which will not blend, with different superheat points and system pressures. Not to mention that R22 won't carry PAG oil through the system as effectively as 134a, meaning you could end up starving your compressor of lubricating oil, thus burning it out.
NO ! and Why?
No. the pressure are different, r22 runs at a fairly low pressure and you shouldn't be worried about blowing your gauges, but you won't be able to determine your super-heat or sub-cooling. for a about $100cdn you can buy the right gauges.
No