hey I was told something about charging a system today that I havnt come across Il give you the details of the system that I was working on, basically its a R404a system thats freezzing down a room to -10.c pretty straight forward well thats what I thought, I changed the compressor, drier and did the usally nitro leak check and vaced it out.

But once I had charged the system to a 90% sightglass my head pressure was up at 300 psi and suction at 80 psi room temp 15.c (was 2 machine working in the room for heat load).....so I was told to put a C.P.R on it (to help the compressor life)but once I got talking to the tech guy at the supplier he ask me what the problem was so I explained what had happened and straight away he said I had over charged it and that todays modern refrigerants shouldnt be charged by sight glass and that sight glasses are just for moisture indication.

he gave me a data sheet to regards of the running amps to suction saturation temp and on this instance the most amps I should be pulling when the room is 10.c or above is 8.99amps So once I got back at the unit I found the unit pullin 9.45 amps I then proceed to remove the refrigerant from the reciever in to my reclaim bottle to see the amps come flying down suction pressure coming down.He also told me when I was charging a new system up that I should only half charge the system wait til the room starts to pull down and keep squirting small amounts until am about 5.c off the set temperature then go back to the condensing unit take the ambient temperature add (12k as its a tropical condensing unit, this is the diff across the condenser) this should give me the discharge temperature if it high ave over charged it.

This is the first instance ave had this problem and I mite of not described the situation well or got my wires cross but it just to see if any one else could shed some light on it.
cheers