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kefah
01-07-2012, 08:51 PM
hi every one
i got 4 ton split unit ac from general type heat and cool
with damaged compressor
so i replaced it with new one from some LRA and size
i checked compressor before installing so compressor worked properly
but when i started charging system i encountered this problem
if i charge the system with required amount of ***** by weight the compressor starting opening safety valves
but if charge system with little amount of ***** by weight the compressor and system work propely
i tried anothre types of ***** 22 and i made clean for the system and i changed the filter and expansion valves
i checked the electrical connection they are properly connected
can any one help me

The Viking
01-07-2012, 09:13 PM
Well, you do have a head start...


You are online.

Do a quick search for air condition or refrigeration engineers in your neck of the woods and ask one of the local guys to sort it out for you.

Sorry, but there is a whole can of worms there that needs specialist knowledge to sort out.

kefah
01-07-2012, 09:16 PM
ok
what is the cause of head start
what is the solution
can you advice me

install monkey
01-07-2012, 09:39 PM
the" head start" viking is referring to is the fact that you have access to knowledge- as long as you are able to provide us with more information like standing pressures,running pressures and compressor running currents- also superheat and subcooling values would be handy too.

ok
what is the cause of head start
what is the solution
can you advice me

kefah
01-07-2012, 09:45 PM
hi install monkey
sorry for misunderstanding
ok i will check these info and answer you later

kefah
01-07-2012, 09:48 PM
but can you tell me why compressor couild open its safety valves
if there is no blockage or overcharged gas or compressor weakness

install monkey
01-07-2012, 09:58 PM
4 ton- 14kw general- heat and cool- heatpump-(4 way valve)- do you have the model numbers of the old and new compressors, when you say you tested the newer compressor- you ran it on a bench to check pumping/operation
safety valve you are referring to the internal relief disc- to bypass discharge gas back into the compressor body.
changed drier and expansion valve - did you vac the system to under 2 torr, did you use nitrogen to purge whilst brazing and again to pressure test the system. - when the comp starts foes the internal relief valve open within 10seconds then its either a weak relief valve,,or overcharged due to non condensibles-air/moisture or the reversing valve is jammed

kefah
01-07-2012, 10:07 PM
i think new compressor was from same type of the old one
i made a properly vacuum
i tested system for leakage
compressor suction and discharge were so good

monkey spanners
01-07-2012, 10:46 PM
Maybe what killed the old compressor is trying to kill the new one?

kefah
02-07-2012, 08:16 PM
hi
i checked the split unit
4 way valve working properly
the problem start when charging reach 40 psi
discharge and suction connection both are not cold

install monkey
02-07-2012, 09:38 PM
at 39psi suction ,whats your discharge pressure?

kefah
02-07-2012, 09:46 PM
i didnt check dis press
i know the problem start when suction connection start cooling

install monkey
02-07-2012, 10:46 PM
did you vac both sides of the system?-(hi and low )- leave gauges connected and charge via the low side - if r22 charge as a vapour if 407c or 410a then charge as a liquid slowly to allow refrigerant to boil off in your gauge line to prevent compressor damage

i didnt check dis press
i know the problem start when suction connection start cooling

kefah
03-07-2012, 08:17 PM
hi every one
thank you for helping me
i detected the cause of damaging compressor
the problem happened because of a device in indoor unit
the device is looks like expansion valve located in the discharge line in begining of indoor unit which is branching into the smaller pipes to the ervaporative coils.
since i didnt use netrogen to cleaning pipes
i only vacuumed it
after opening it by welding it was containing alot of slug and corrosion
so i changed it
thank you again
and sorry if made you tired with me
your replays helped me in solving problem

install monkey
03-07-2012, 09:44 PM
well done- we all learn on here!

kefah
03-07-2012, 09:46 PM
thank you master for helping me
but i have question
if i have dirty system how i can clean it
by nitrogen or by what

install monkey
03-07-2012, 10:06 PM
if the system is clogged- then degas from both sides of the system.cut out the drier- blow nitrogen down the suction line for a few minutes this will move any crap and exit the system at the open end where the drier was,and again add nitrogen into the discharge side again for a few minutes to clear crap again out where the drier was. then fit a new drier but slowly add nitrogen into the high side and leave the low side gauge connected to the system but disconnected from ur gauges- the nitrogen that passes through the system is verly low - not hissing , then vac and recharge with new gas- if the nitrogen is too much then youll struggle to braze the new drier in

kefah
03-07-2012, 11:04 PM
thank you man you helped me

DEVITG
08-07-2012, 08:12 PM
Use a BURNT out FILTER at the suction line before the compressor

kefah
08-07-2012, 08:23 PM
what you mean by burnt out filter

monkey spanners
08-07-2012, 08:28 PM
what you mean by burnt out filter

A burn out drier has a different filter in it to adsorb acid etc caused by a compressor burn out.

kefah
08-07-2012, 08:30 PM
thank you every one

install monkey
08-07-2012, 09:15 PM
suction burn out drier is fitted as close to the compressor on the suction line- then regular checks of the pressure drop accross the drier-note they are meant to be removed after a while-but no one usually removes em

every time u do a compressor change do an acid test on the oil- if acidic then fit the suction burn out drier- also acid away - is a neuraliser u can add to the new compressor prior to fitting

DEVITG
09-07-2012, 12:12 AM
I usually use one or two size bigger than needed , to your case a 10 ton will be good.
So you do not have to worry about pressure drop.

kefah
16-07-2012, 08:01 PM
thank you every one