99 ZX2 A/C
 

Cold air gradually (4-5 months) declined to now blowing warm air. Compressor kicking on and off within seconds. Don't know if low on R-134 would cause comp. to do that. Have a gage but not sure where low side is and 50/50 ain't good odds. Any suggestions?

this may be a bit late, but the low side is after the evaporator, follow the lines from the compressor, if one heads to the condenser (radiator looking thing in front of car) then thats the high side... you may want to have your low pressure switch checked before you add refrigerant, because too much will cause it to blow warm. also if you can, have a dye placed in the system if you do add fluid so you may find a leak later.

Hi side and lo side service fittings are different sizes. Low pressure WILL cause the compressor to cycle frequently. (fail safe pre-caution)