compressor start issues

[jonnho]

i have worked recently with the new lg refrid. lrsc26905tt
the compressor was having starting issues. the unit would not run or start the compressor at all. the compressor was changed. i replaced it with a new compressor. the compressor seemed to work at first during the charging. i filled the system to the manufactes reommended freon level 4 ounces. the compressor started. i finisheed the fill . i pulled the plug and waiting 10 or 15 minute to try to restart the compressor. the compressor now will not start. the overload has kicked out. i was not sure if i have a vapor lock or if some one has come across this issue before. the unit was vacumn down and recharged as far as i know correctly. does anyone have an ideas or tips?

[HayZee518]

When you swapped out the compressor did you do a complete system evacuation? You needed a vacuum pump capable of at least 30 inches of mercury of vacuum. This you hitch up to the low side valve and purge the system for a minimum of 24 hrs. Then you shut off the pump and close the valve and watch the gauge another 24 hrs to see if it will hold the vacuum. If it will, you then feed gaseous freon to the low side NOT liquid! They make a charging station that heats and vaporizes the freon into a gas. Was this replacement compressor new? or just another compressor from another unit. A refrigeration supply house will have a "hot-start" kit for stuck compressors. It is possible to reverse a compressors direction to un-stick was was stuck except in the most difficult cases. When you pulled a vacuum and added freon did you add the proper amount of compressor oil to the unit? Usually when you pull a vacuum everything in the lines comes out - even oil for lubrication. You need to put this lube oil back in the unit for it to work. chances are that now the whole compressor is bound up due to lack of lubrication - might as well throw this one away.

[jonnho]

i did pull the vacumn the pump is a deep vacumn pump . i did get the compressor to start. the unit starts fine now. the compressor starts and runs. the only thing is the low pressure and the high pressure side will not cool or heat all the way threw the pipes. the evap coils get cold but only the first line of the coils. the same happens with the condensor coils. the line going in get hot but the rest of the coils never get warm now. i am thinking the metering line is plugged now. the metering line may have caused the compressor to go bad in the first place. what do you think....

[HayZee518]

OK high side pressures should be around 225 psi - low side around 50 for r-12. The low side should be cool to sweating, the high side lukewarm to slightly hot. the high side line and the evaporator cappillary forms the pressure drop orifice where the liquid turns to gas and absorbs latent heat. if there is scale in the line refrigeration will be slow at this orifice.

[jonnho]

got the compressor running

the unit had the wrong comppressor. the company sent me the wrong compressor type. it looked the same but was differnt start cap. the metering line was also plugged. i could not fix the unit the vacumn did not come threw metering line it stopped at the evaporator coils. the unit had to be replaced thanks for the tips....