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diy mini split "quick connect" linesets

3046 Views 10 Replies 4 Participants Last post by  bfrabel
Mr Cool diy mini split

How do you know you have fully tightened the connection without tightening too much or too little when you are using 2 adjustable wrenches as advised

Will you hear the connection being pierced for each of the 4 connections you make with the 25ft of lineset?
Once you tighten the quick connections from the outdoor unit lineset to the 25ft of lineset, will you be able to tighten those lines any further without turning off the valves at the outdoor unit, if they require more tightening later, or do you need to turn off the valves with the allen wrench?

Lastly, how do you find out the pressure inside of the lineset lines as it seems it needs to be over 300psi for heating?
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Mr Cool diy mini split

How do you know you have fully tightened the connection without tightening too much or too little when you are using 2 adjustable wrenches as advised
Just snug them up tight... they have O-ring seals so you don't really need to get them extremely tight.

Will you hear the connection being pierced for each of the 4 connections you make with the 25ft of lineset? Probably not on all 4 of them... not a problem.

Once you tighten the quick connections from the outdoor unit lineset to the 25ft of lineset, will you be able to tighten those lines any further without turning off the valves at the outdoor unit, if they require more tightening later, or do you need to turn off the valves with the allen wrench?
You can tighten those connections any time you need to with no regard to shutting off any system valves.

Lastly, how do you find out the pressure inside of the lineset lines as it seems it needs to be over 300psi for heating?
Measuring system pressures is only to be done by trained personnel using a gauge manifold and proper safety procedures when there is some reason to suspect a problem may exist... not necessary for end users.
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if the p-4 error is only coming up when testing the heat function at 83f , could the error possibly be due to the quick connections not being fully made? if so,what are the steps to turn off/on the refrigerant lines to test the quick connect connections to be sure 100% of the refrigerant is flowing thru the refrig lines?
What does the P4 error mean?
I don’t like the quick connection lines. In my experience 95% of them wind up leaking.
Make sure to not make an oil trap with the extra lineset.
Have you opened the system valves as instructed in the installation directions. You will need to follow those directions to put the system in proper operating condition. It sounds like the valves may be closed (fully clockwise). They are required to be opened fully counterclockwise until snug and then 1 turn back clockwise. Read the directions.
the instrux were followed so the valves were opened at the outdoor unit , counter clockwise until snug but i haven't turned back clockwise once as the instrux didnt mention that.

when the unit is set to the coldest temp, the air coming out is 60F with temp outside at 65f. when the unit is set to the warmest temp to test heating, it produces the p4 error.

i checked all electrical connections

P4 - Inverter compressor drive error but like roughneck asked... what does that mean?

could the lineset connections be not fully made which would cause the refrigerant to not adequately flow?

if so, what steps do i need to take so i could tighten those connections / improve the flow? it's difficult to know what's tight enough but not too tight
Refer to the link below for more information and where to get warranty help if you have followed all the directions and still get the P4 error.


Error Codes and Warranty Help
thanks.that's the video i saw before posting here.

how do i know whether the lineset connections are fully made? from some videos it appears that there should be no visible threads. is that true?
thanks.that's the video i saw before posting here.

how do i know whether the lineset connections are fully made? from some videos it appears that there should be no visible threads. is that true?
Yes, that pretty accurate... most or all of the threads will be hidden by the skirt of the nut. Normally when tightening that type of connector it will initially turn easily for the first few turns and then you will feel a noticable resistance. Continue turning and that resistance will fade. Continue tightening until it comes to the end and you are unable to tighten it any further... don't be afraid of overtightening it... make it snug. You're not really sealing it any better but just making sure you have it all the way pierced and open to flow.
it worked! after all the reading and researching on torquing and getting a clear message that you don't want to overtighten or undertighten, i felt a lot of pressure to get it just right.however, doing the additional tightening did the trick as the cooling readings showed 32F & heat readings were over 100F when putting the unit to the test at the maximum cooling & heating temps. no error codes. wheww, thanks very much : )
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Call Mr. Cool, that's my name, that name again is Mr. Cool!
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