# Troubleshooting Mini-Split



## kmachn (Jul 26, 2011)

My new mini-split (Fujitsu 9RLS) is not heating. It cooled great this summer and heated well on a cool day in September when I tested the heat. It then was not working well during cooling, and now not heating. The refrigerant lines at the outdoor unit EDIT: were cold to the touch, no temperature difference between them. The indoor unit showed a "refrigerant cycle error" at one point. I'm having an HVAC guy come out tomorrow, but am hoping to try some things first. Any suggestions on what I could try before he comes out? Thanks


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## biggles (Jan 1, 2008)

run the unit in HEATING grab the insulated line into the evap fan section if you can grab it and its warm your charge is low....that temp is the hot gas directly off the compressor...180F no matter what the temp is outside andif you swing it to cooling with in the condenser that is the line that goes to the condenser coil before turning into liquid...on the heat pump cooling mode...if the guy just bangs some gas in a leaves you might not make it thru the winter..so push for a good leak check if you see him go for the feorn walking in.


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## harleyrider (Feb 20, 2007)

biggles said:


> run the unit in HEATING grab the insulated line into the evap fan section if you can grab it and its warm your charge is low....that temp is the hot gas directly off the compressor...180F no matter what the temp is outside andif you swing it to cooling with in the condenser that is the line that goes to the condenser coil before turning into liquid...on the heat pump cooling mode...if the guy just bangs some gas in a leaves you might not make it thru the winter..so push for a good leak check if you see him go for the feorn walking in.


 
i agree 100%......if the unit is low on freon its coz you have a leak....you will want that leak repaired.....you should never have to put freon in a tight system.


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## kmachn (Jul 26, 2011)

biggles said:


> run the unit in HEATING grab the insulated line into the evap fan section if you can grab it and its warm your charge is low....that temp is the hot gas directly off the compressor...180F no matter what the temp is outside andif you swing it to cooling with in the condenser that is the line that goes to the condenser coil before turning into liquid...on the heat pump cooling mode...if the guy just bangs some gas in a leaves you might not make it thru the winter..so push for a good leak check if you see him go for the feorn walking in.


I just reread my initial post, apparently I thought I included some information that I must have accidentally deleted. I did touch/feel both lines outside in heating mode, no difference between them in temperature. Both were cold, which is what made me think it is a refrigerant issue. Anything else that could cause that? The outside unit was running, so it's not that it wasn't getting power or anything obvious. 



harleyrider said:


> i agree 100%......if the unit is low on freon its coz you have a leak....you will want that leak repaired.....you should never have to put freon in a tight system.


I installed the unit myself, but had someone come out to pull a vacuum on it. He had a fancy digital manifold (I think it was a $300-$400 Fieldpiece version) and he _said_ that he could determine if there was a leak based on some information it was telling him. He said it was good and tight, which is really the only reason I'm thinking it _may_ be something other than refrigerant. But, that doesn't guarantee there wasn't a leak or that one may have developed later. He hasn't returned my calls, so I've called someone else to come help diagnose. Is it possible that the connections have come loose? I did use "Leak Lock" on the flared connections, but I suppose they still could have come loose.


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## biggles (Jan 1, 2008)

if your in the heating mode and the insulated line isn't hot to the touch your short of the charge right above a low pressure trip....you say the condenser is running is that just the fan or do you actually hear the compresor running...sorry had to ask:wink:...if you had a micron test and it was below 1000 microns thats well on its way to mint vac check...might of developed a leak.or somebody snorted your freon....on a commando raid on night.do you have guage readings in cooling and or heating?i would have him recover the balance of the freon and revac to see if you go below 5000 after a 1/2 hour pull if the system is leaking you'll never go below 5000 microns and when you isolate the pump it will move up to 10,000 within an hour.keep in mind if it is cold out you might have freon in the oil of the compressor and this will give you a false leak reading as the freon boils off from a vac and pressurizes the system.is that a home run from the evap to the condenser with pre charged tubing....see any oil residure on the locking nuts on the lines at either end....


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## kmachn (Jul 26, 2011)

biggles said:


> if your in the heating mode and the insulated line isn't hot to the touch your short of the charge right above a low pressure trip....you say the condenser is running is that just the fan or do you actually hear the compresor running...sorry had to ask:wink:...


No need to apologize, legitimate question. The compressor was running, and was in fact a little noisier than usual. Would that be a common symptom if it has lost it's charge?



biggles said:


> if you had a micron test and it was below 1000 microns thats well on its way to mint vac check...might of developed a leak.or somebody snorted your freon....on a commando raid on night.do you have guage readings in cooling and or heating?i would have him recover the balance of the freon and revac to see if you go below 5000 after a 1/2 hour pull if the system is leaking you'll never go below 5000 microns and when you isolate the pump it will move up to 10,000 within an hour.keep in mind if it is cold out you might have freon in the oil of the compressor and this will give you a false leak reading as the freon boils off from a vac and pressurizes the system.is that a home run from the evap to the condenser with pre charged tubing....see any oil residure on the locking nuts on the lines at either end....


I don't think there was a commando raid, but my 2 year-olds been acting goofy so maybe he hacked in and started snorting the stuff. :laughing:

I'm not sure how many microns he pulled it too (sorry if that's the wrong terminology) but he sounded confident there wasn't a leak. I don't have a set of gauges or know how to use them, so I don't have any readings. I know he wants to check the charge as a last resort, so I think we'll only go there if he can't find something else but I'm hoping there may be something obvious I'm missing. Sounds like it's almost certainly a lack of refrigerant. 

I'm not up to snuff on the HVAC terminology, so I'm not sure what you mean by a "home run", but the unit was pre-charged with the refrigerant, not the lines. Also, I stayed in spec on the length of the lines...just in case that was the next question. 

I only glanced for oil residue, but I'll check all areas I can this evening if I get a chance before it gets too dark. Or I'll check with a flashlight. One set is in the attic space, so that won't be fun...but at least they're accessible. I really do appreciate the help. Any other words of wisdom, or things to check?


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## biggles (Jan 1, 2008)

Home run term... is the only connections are at the condenser and evap no brazed elbows or couplings between.if your lines weren't charged with freon then he pulled a vac on those before connecting them? then screwed them onto the evap and condenser let the lines take the charges and topped off the system on start up...?do you understand that the discharge of the compresor is your heating if you only have the 2 connections on each end just grab the rotor locking nuts "connects the line sets" and see if your hand fingers have oil on them


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## Marty S. (Oct 31, 2009)

Spray a soap and water solution on all the flare connections,should be four. Leak lock would hide any leaks from a bad flare under a vacuum but get gooey and blow out under 300psi of pressure and the heat. If one is bad have him redo all of them.


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## kmachn (Jul 26, 2011)

Home run...yes, no connections on the lineset except at the flared connections at each end. I got home and checked the outside two, those were both fine. No bubbling of Leak Lock or oily residue. I'll get up in the attic and check the other two when I get a chance this evening. I have to pick up the kids...

The lines were connected to the evaporator and condenser, then he pulled the vacuum. No changes have been made to the lines since then...except for running the system. He didn't have to add any refrigerant, since the system was pre-charged with an adequate amount for the length of lineset.

I was VERY careful with not "crimping" the lineset when unrolling. This probably would have easily showed up when he vacuumed it if there was a problem, right?


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## biggles (Jan 1, 2008)

:huh:the line set is part of the charge when connected if you didn't have freon in the entire system(evap/cond/lineset) prior to connection the system was installed short...that's why i wondered why you pulled a vac on a prechaged system.but you stated the cooling worked great and so did the heat...or was it short just running longer to make temps..now with lower temps the unit is tight vac wise but short on freon with no leaks


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## hvactech126 (Nov 11, 2010)

Or you have a bad reversing valve, coil, or control board...... Just throwing that out there.


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## Marty S. (Oct 31, 2009)

They're just like a regular split system biggles. Only the condensing unit comes charged but it's enough for X length line set(length given in the directions) and the evap. Lines and evap are supposed to be connected via 45 degree flare fittings and torqued to a specific value( in the manual),vacuumed to 250 microns then charge released by opening the service valves. 

Still sticking to my leak lock failed theory. Hopefully that's all it is...easy enough to fix.


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## kmachn (Jul 26, 2011)

Marty S. said:


> They're just like a regular split system biggles. Only the condensing unit comes charged but it's enough for X length line set(length given in the directions) and the evap. Lines and evap are supposed to be connected via 45 degree flare fittings and torqued to a specific value( in the manual),vacuumed to 250 microns then charge released by opening the service valves.
> 
> Still sticking to my leak lock failed theory. Hopefully that's all it is...easy enough to fix.


Yes, what Marty said above is how it all works. I could have done it wrong, but I did follow the installation instructions pretty closely.

The funny thing about looking for something...it's always in the last place you look. The first 3 connections I checked were fine, the 4th was very oily. It appears as though it is coming from the factory side of the connection, but I am not so arrogant to think that the problem just happens to be a factory problem and not the fault of a homeowner DIYer. At this point, I guess I will redo all of them if that is the suggestion. Better safe than sorry.

Should I use the Leak Lock again, or is it not worth the trouble. Is it the problem, or did it just mask the problem? I only used it based on some "expert" recommendations.


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## Marty S. (Oct 31, 2009)

No on the leak lock. It didn't cause the problem but covered it up...for a while.


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## kmachn (Jul 26, 2011)

Should I use anything on the joint or just make sure I torque it tight?


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## Doc Holliday (Mar 12, 2011)

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. :thumbsup:

Good luck.


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## harleyrider (Feb 20, 2007)

has anyone givin any thought to the fact that maybe the compressor is not running?


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## kmachn (Jul 26, 2011)

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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## biggles (Jan 1, 2008)

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:whistling2:


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## kmachn (Jul 26, 2011)

biggles said:


> 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:whistling2:


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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## biggles (Jan 1, 2008)

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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## hvactech126 (Nov 11, 2010)

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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