compressor terminal blow up cause

[kefah]

Hi all
i got 12000 BTU R22 ac Split unit with shorted compressor]
so i installed new one
charged by weight

it was cooling very good
for one day
after 1 day perfect work
i got call its not cold and trip circuit breaker
got there to find that compressor both C & R blown up
with black residue around it
what the cause behind 2 terminal blow up???

[al]

Whatever caused the first compressor to short has caused the second to fail. flush the system pipe work, maybe install a suction filter (if cooling only unit), run nitrogen through the lines and pressure test, then a good vacuum.

[install monkey]

common an run terminals scorched /blown- overcurrent from a seizing compressor?, did you replace the original electrics, capacitor, relay

[Craig Johnston]

Sounds like you could have acid in the system.

[vikky1971]

@kefah, with 599 post as of today you sure are expert!
System, sure, must be having solid particles which have damaged the compressor motor windings thus leading to heavy short circuit current flowing through the terminals and eventually burning them. Before your next venture with new compressor, blow thoroughly the entire system with nitrogen, make sure system is clean of any solid particles. Install a filter cum dryer prior compressor, before releasing gas into the new compressor + system, good vacuum is essential.
Can brazing be avoided? Instead Use brass compression unions if possible.

[vikky1971]

Posted twice, regrets!

[Brian_UK]

Good to hear from you Kefah, hoping you are still safe.

[Glenn Moore]

kefah
when changing a burnt out compressor it is important to protect the new compressor from the burn out contaminants in the system. Most modern day compressors have in built safety components such as Klixons or thermistors which normally prevent the total destruction of the motor windings. But in any hermetic or semi hermetic system the combination of oil, refrigerant, heat electrical arcing in the motor etc will cause weak acids to manifest themselves in the oil and refrigerant and these acids start to attack the motor insulation (shilac) and bare electrical parts inside the machine. Poor evacuation of a system will make the situation worse.
So when fitting a replacement compressor it is necessary to fit a BURN OUT Drier to the suction line close to the compressor, and ideally a standard drier in the liquid line exiting the condenser.
The Burn Out Drier core is made from pure Activated Oxides which will remove any acid products from the suction gas and oil returning to the compressor, thereby protecting the new compressor, the drier in the liquid line has a combination core made up from silica gel, molecular sieve, and a small percentage of activated Oxides, this drier will remove any moisture in the system and also some of the acids.
After a few days these driers can be replaced with new ones and after that they can be totally removed from the system, as you remove the acidic contaminants with the used driers.
It sounds that the system is badly contaminated so to prevent more burn outs make sure a good quality BURN OUT drier is fitted to protect the compressor. Many engineers make the mistake of changing the compressor and sometimes the liquid line drier but fail to fit the most important one the BURN OUT drier. All the manufacturers manufacture them

[kefah]

common an run terminals scorched /blown- overcurrent from a seizing compressor?, did you replace the original electrics, capacitor, relay

i replaced only wires

[kefah]

Sounds like you could have acid in the system.

i didnt flush the system

[kefah]

ok thank u all for important advice
my question could acid damage compressor after 1 day???

as i think it could take longer time

[kefah]

@kefah, with 599 post as of today you sure are expert!
System, sure, must be having solid particles which have damaged the compressor motor windings thus leading to heavy short circuit current flowing through the terminals and eventually burning them. Before your next venture with new compressor, blow thoroughly the entire system with nitrogen, make sure system is clean of any solid particles. Install a filter cum dryer prior compressor, before releasing gas into the new compressor + system, good vacuum is essential.
Can brazing be avoided? Instead Use brass compression unions if possible.

for dryer filter u talk u correct
i will be more careful next time