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Old 11-28-2011, 08:34 PM   #16
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Troubleshooting Mini-Split


Okay, so we know the problem. What I would do if I was the tech was first recover all refrigerant and get that out of the way. Than I'd fix the leak. Then I'd nitrogen pressure charge it to well above operating pressure. On regular residential split systems I go to 250-300 psig and let sit there for 15 minutes. At this point I could use some soapy water to check all connections but with 200 psig on a mini split a leak will show in my gauges relatively quickly.

If good after approximately fifteen minutes and with compressor still open, vacuum to below 500 microns, weigh in charge and start it up and top off if at all needed.

If you are wondering why I said to recover and not re-use the old refrigerant or not just pump it down int othe compressor, when there is a leak you stand a greater chance of also sucking air. Refrigerant out, air into the lines.

Anyways, that's what I'd do and I know you wouldn't be calling me for years and years. At least not for that system.

Good luck.


Last edited by Doc Holliday; 11-28-2011 at 08:37 PM.
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Old 11-28-2011, 08:55 PM   #17
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Troubleshooting Mini-Split


has anyone givin any thought to the fact that maybe the compressor is not running?
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Old 11-28-2011, 10:44 PM   #18
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Thanks for all of the help, including the recommendations Doc.

A couple of last questions, if anyone is still feeling helpful in this season of giving...

1. The system ran for at least hours, maybe a day but definitely not weeks either without or very low on refrigerant. Should I expect any possible damage to system components, or are they designed to withstand these types of situations?

2. Doc recommended recovering the refrigerant before fixing the leaks. Would it be problematic to fix the leak/tighten up the joints first, or would this create a problem? The area in the attic is not easy to get to, and I don't know if someone else could get to it since it is a tight fit. If I can fix it before he comes out, it could save some time...and maybe save me some money.
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Old 11-28-2011, 11:02 PM   #19
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Troubleshooting Mini-Split


the noisy compressor could be a lack of balanced freon returning to the compressor scroll or rotary) and definitly a lack of oil it's not supper critical but if the freon is low just above trip and running the compressor will pull anything it can out of the suction side....the compressor overload klixon is the only safty to react from lack of oil opening the one side of the 208Vs...6ozs of oil during revac suck in won't kill you just have to by a gallon ... is the system R-22?.thinking the line set had a 1/3rd of the install charge i have seen rooks looking like a spagetti works with rolled line sets because they wanted a quick install connected job slame the rotor locks at each end..and start it up.if you have locks and not flares just 2 adjustables just past each other and grab them with both hands and.squeeeeeeeze them to get a tight lock no sealant required....there is a teflon ring inside them so wst that leaker heated up..should be removed on torching then cooled oiled up and reinstalled...just a thought
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Old 11-28-2011, 11:23 PM   #20
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Troubleshooting Mini-Split


Quote:
Originally Posted by biggles
the noisy compressor could be a lack of balanced freon returning to the compressor scroll or rotary) and definitly a lack of oil it's not supper critical but if the freon is low just above trip and running the compressor will pull anything it can out of the suction side....the compressor overload klixon is the only safty to react from lack of oil opening the one side of the 208Vs...6ozs of oil during revac suck in won't kill you just have to by a gallon ... is the system R-22?.thinking the line set had a 1/3rd of the install charge i have seen rooks looking like a spagetti works with rolled line sets because they wanted a quick install connected job slame the rotor locks at each end..and start it up.if you have locks and not flares just 2 adjustables just past each other and grab them with both hands and.squeeeeeeeze them to get a tight lock no sealant required....there is a teflon ring inside them so wst that leaker heated up..should be removed on torching then cooled oiled up and reinstalled...just a thought
Thanks for the quick feedback, but to be honest I'm not sure I understood everything you said. Here is what I did catch.

The compressor is probably OK, just making a little more noise because of the lack of refrigerant.
The refrigerant is R410a to answer your question.
The connections are flared. This doesn't need to be heated/torched to get loose, right?
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Old 11-29-2011, 12:16 AM   #21
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Troubleshooting Mini-Split


just ramblin'hvac talk...but no no torch is required to remove or reinstall but be sure you backup the tight down wrench on that last tightening..410A isn't R-22.....running pressures be careful the only thing on the oil was as much as the freon leaked droplets of oil went out also.....if this guy has some 410A oil 6 OZ during a vac pull for peace of mind...and note to him charge it in the heating mode then flip it into cooling and record the outdoor air on both runs....get a split also on the evap unit during heating and cooling once that leak is fixed should do an easy 250MICRONs ona vac test...refrig might be boiling off....so be patient
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Old 11-29-2011, 06:37 AM   #22
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Troubleshooting Mini-Split


biggles you cant charge these while they are running other than by weight. Often they only have a port on the gas side of the system.

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