A/C and Coolant Questions

My girlfriend has a 1997 Quad 4 with 140,000 miles on it and I want to flush the cooling system and replace the antifreeze.I have read quite a few threads on here about this but I am still wondering if it makes any difference if I use the green or orange coolant;I believe this car came with the orange but has been topped off with the green.As I understand it the only difference is the drain interval.Do I need to install a flush kit on the heater hose or just use the type that you pour into the reservoir and do I absolutely,positively have to flush the radiator to make sure I get the mixture of green/orange antifreeze out or just go with one or the other?The car is in another city right now so I cannot inspect the radiator drain;is it the wingnut type or do I need a special tool?I bought the Haynes manual to give me some idea what I am looking for,but all it says for coolant capacity is 7.5 to 13.6 quarts;any idea what it is for this car?

Also,the a/c is not blowing cold again;Connie had a can of 134A put in a few months back and all was well until recently.I can find the high side with the red cap but all I find above the compressor is a blue cap with a tag that says EVAP something or the other on it;is this the low side or do I need to look under the compressor for it as I have seen mentioned in a thread?The manual is no help as far as giving me any range for the PSI that may tell me if it just needs another can of 134A (for whatever reason)or if I have other problems.

Any thoughts on the subject(s) will be greatly appreciated.

should be using the long life coolent because it has the proper lubrication viscosity the coolant system requires. The tecs in the shop use a garden hose to flush the coolent systems. ill look into how gm does it.

We use a Flush machine @ work, you hook it up to the rad hose and @ the rad. it is pretty sweet. When the car get warm enough and the t-stat opens turn the machine on and in pumps the new and out comes the old.
Yeah I would use what is originaly recomended for the car.