Mini split repair

WyrTwister · 07-22-16, 05:05 AM

On both of our MS's , I used an old Craftsman flare tool that I have had 35 - 40 years . I obsessed over the angle , so I did a trial fit . I came to the conclusion , is coated inside and outside with Nylog Blue , the copper tubing is soft enough that that it will conform to the angle of the flare fittings .

The expansion device is inside the outside MS unit . In A/C mode , the refrigerant will flash and cause the line to frost , if given a chance ( low pressure area ) . If you are low on refrigerant , you will have low pressure on the suction side of the system .

Would be best not to run it low on refrigerant . This is my opinion , others may disagree .

A small oil loss is probably not a problem ( a few drops ? ) . The outdoor units come with enough oil for the max allowable line set . How long are your lines , compared to that number ?

I use UV dye on automotive applications . And the little UV flashlight . If in doubt , add a little when you add refrigerant .

Put your gauges on and check the pressures ( after your refrigerant arrives ) . Run it briefly & check to see what the pressure is at the suction side . As long as it has some positive pressure , running , no air / moisture could have gotten into the system .

I would leave it with a few pounds of positive pressure & weigh the amount of refrigerant added , according to factory data . If you can , add it as liquid . R410a is a mix of at least 2 refrigerants of slightly different boiling points . If you add refrigerant as a gas , constantly shake the refrigerant tank to keep the vapor mixed .

Best I remember , you did a self install ? You gained the knowledge base to do a repair , now . :-)

God bless
Wyr

07-22-16, 05:05 AM	#21
WyrTwister Master EcoRenovator Join Date: Jun 2013 Location: USA Posts: 543 Thanks: 6 Thanked 44 Times in 38 Posts	On both of our MS's , I used an old Craftsman flare tool that I have had 35 - 40 years . I obsessed over the angle , so I did a trial fit . I came to the conclusion , is coated inside and outside with Nylog Blue , the copper tubing is soft enough that that it will conform to the angle of the flare fittings . The expansion device is inside the outside MS unit . In A/C mode , the refrigerant will flash and cause the line to frost , if given a chance ( low pressure area ) . If you are low on refrigerant , you will have low pressure on the suction side of the system . Would be best not to run it low on refrigerant . This is my opinion , others may disagree . A small oil loss is probably not a problem ( a few drops ? ) . The outdoor units come with enough oil for the max allowable line set . How long are your lines , compared to that number ? I use UV dye on automotive applications . And the little UV flashlight . If in doubt , add a little when you add refrigerant . Put your gauges on and check the pressures ( after your refrigerant arrives ) . Run it briefly & check to see what the pressure is at the suction side . As long as it has some positive pressure , running , no air / moisture could have gotten into the system . I would leave it with a few pounds of positive pressure & weigh the amount of refrigerant added , according to factory data . If you can , add it as liquid . R410a is a mix of at least 2 refrigerants of slightly different boiling points . If you add refrigerant as a gas , constantly shake the refrigerant tank to keep the vapor mixed . Best I remember , you did a self install ? You gained the knowledge base to do a repair , now . :-) God bless Wyr