multi zone split whistles, doesn't heat

mthmlf84

hi guys, I installed a LG multi max 60Kbtu 4 zones ducted split system in my house upstate new york where temps currently range between 20-35F.

Pulled the initial vacuum, waited for 2 hours and released the refrigerant because it was holding it perfectly, only to realize later that I had to pull a triple vacuum and do a nitrogen leak check. When i try to call for heat, it stays in pre heating mode forever, the compressor kicks on and whistles and it never kicks into heating mode.

When I try to check the refrigerant pressure at the low side with my manifold gauge, I get absolutely nothing, zero. Not sure if that means a leak developed and sucked everything out, but it sounds like it, right?

I'd like to recover the refrigerant (if there's any left) in the compressor and do the proper triple vacuum, nitrogen leak test procedure, but I'm not sure where to start. It's too cold to get the unit to go into AC mode, heat doesn't work, etc. Any hints on what I should do?

I have a manifold gauge, a good 7cfm vacuum pump, a bottle of nitrogen with the gauges/valves that came with it. Any tips would be greatly appreciated. Thank you!

wmgeorge

You need an education in basic HVAC or hire someone to do it right. Correcting the mistakes is job one. Then you would know holding for one thing, holding a vacuum is like saying I pressure checked using 15 psi pressure!

mthmlf84

My idea of getting an education is reading about stuff, doing it, then asking people who know better if they can point me to things I might have done wrong, try again, etc.

vtfarmer

Take a one day class at a community college or trade school to obtain the EPA section 608 certification, this will solve two problems: you will (if you pass the core and Type II exams) obtain the credential legally required to work on this system and 2) you will learn about about the practices and tools required to do this type of job that the reading and video watching you do will have a foundation to build on.

You need a recovery machine and suitably sized bottle and you'll likely need to replace the R410a charge after you properly fix the leak(s) and evacuate the system. Take a section 608 class: you'll have a better idea of what you need to do generally, the service literature for this specific system will probably make more sense, and you'll be able to legally buy the replacement charge and do the work.

mthmlf84

That’s awesome thank you. I’ll look up that class and definitely take it. I wonder how the leaks happened, will be interesting to find out. It’s been very cold and I now understand that I did very little to remove humidity from the lines, maybe it’s related to that. All the copper lines were flared properly and torqued to spec, etc.

pecmsg

mthmlf84 said:

That’s awesome thank you. I’ll look up that class and definitely take it. I wonder how the leaks happened, will be interesting to find out. It’s been very cold and I now understand that I did very little to remove humidity from the lines, maybe it’s related to that. All the copper lines were flared properly and torqued to spec, etc.

Did you re-flair the factory ends?

wmgeorge

Proper procedure is to pressure check first with nitrogen, check for leaks at the flares usually and if you have never flared before my guess they leak. Then pull a vacuum my guess the system is full of air and the R410a is contaminated with moisture. Doing HVAC work is more than watching You Tube videos.

DJD775

mthmlf84 said:

My idea of getting an education is reading about stuff, doing it, then asking people who know better if they can point me to things I might have done wrong, try again, etc.

As a fellow diy'er you are on the right track but why ask the pros after you performed the work instead of before?
The way I see it you want read, read, and when you think you know what is going on read again! Then ask questions and when you are almost 100% sure what you are doing then perform the work.
I've contemplated doing some AC work myself but the additional tools, e.g. recovery machines, and knowledge needed to remediate any mistakes just didn't make sense to me.

GW

All of us had to start somewhere. when I started doing AC 20 years ago, I thought I knew what I was doing, but not so much. The way we do a vacuum today versus even 10 years ago is way different, 

Torque wrench, did not know what that was five years ago.(Well, I’ve owned a torque wrench is since I was a teenager, you know what I mean). This flare nuts need to be torqued just right

nobody puts traditional gauges on the mini splits these days. Unless you’re gonna go through the steps of pre-charging your hoses. When I need to check pressure, I use a core presser and a Bluetooth pressure sensor,/tool such as Testo, fieldpiece.

We do everything we can to avoid hooking up gauges. The easiest and very thorough way to check charge is to just check the split in heating mode, or cooling, whatever season you happen to be in. AC you have to factor humidity, I’m starting to ramble a little bit

Seems strange, if you actually held a vacuum, 98% of the time that means you’re good to go.

Pulling a vacuum on the condenser is a total pain. You’re going to be pumping for a while. Happy to help you, shoot me a picture of your vacuum set up, I’ll let you know if it’s good bad or ugly.

GW

Are you saying it did not work from the beginning?

You’re 100% sure your wiring is good?

wmgeorge

How do you pressure check without putting gauges on? Or at least the gas line. How do you get the nitrogen into those lines? Holding a vacuum means it will hold 15 psig, R410a can run up to 500 psig.

I got my training back in the mid 70's, you always pressure checked before vacuuming a system. Always used a micron gauge and deep vacuum instead of triple evacuating.

These mini splits are critical charge, if you screw up and have leaks and then do a vacuum then your going to pull air and moisture in those systems.

The Mitsubishi service manual gives all sorts of pressure charts for a cross check but the only way to charge correctly is recover what you can, in this case the refrigerant will be full of moisture and air.

Recharge by weight, accounting for all those heads and lines, and that is a calculation for the service manual to address. These are expensive and difficult to work on correctly, easy to screw up.

pecmsg

mthmlf84 said:

hi guys, I installed a LG multi max 60Kbtu 4 zones ducted split system in my house upstate new york where temps currently range between 20-35F.

Pulled the initial vacuum, waited for 2 hours and released the refrigerant because it was holding it perfectly, only to realize later that I had to pull a triple vacuum and do a nitrogen leak check. When i try to call for heat, it stays in pre heating mode forever, the compressor kicks on and whistles and it never kicks into heating mode.

When I try to check the refrigerant pressure at the low side with my manifold gauge, I get absolutely nothing, zero. Not sure if that means a leak developed and sucked everything out, but it sounds like it, right?

I'd like to recover the refrigerant (if there's any left) in the compressor and do the proper triple vacuum, nitrogen leak test procedure, but I'm not sure where to start. It's too cold to get the unit to go into AC mode, heat doesn't work, etc. Any hints on what I should do?

I have a manifold gauge, a good 7cfm vacuum pump, a bottle of nitrogen with the gauges/valves that came with it. Any tips would be greatly appreciated. Thank you!

Mini Split manufactures want a Minimum 500PSIG standing pressure test for 24 hours. If that holds triple evacuation to below 500 Microns before releasing the charge and adding the additional required by the manual.

mthmlf84

GW said:

Are you saying it did not work from the beginning?

You’re 100% sure your wiring is good?

Thanks for the message! I’m doing my EPA 608 class and reading/rereading the manual, making sure i have the equipment i need to try to fix what I did wrong, will definitely post my setup when it’s ready. I got a digital gauge, different hoses and fittings, valve core removers, ball type valves to isolate service connections if needed, big blue leak tester, an old school manifold, a nitrogen bottle with a regulator...

I’m 95% sure the electrical is good. 8ga armored wired in the right place, grounded well, spade terminals, surge protector at the outdoor disconnect, 14 4 comm/power wires all with spades going to the distribution box and to indoor units. The indoor units work in fan mode at different fan speeds, don’t do anything in cool mode because it’s too cold for it to accept a cool signal. In heat mode, any of the indoor units pre-heats for a while, then the compressor outside kicks on after a while with a high pitched, shrill whine. I get no pressure at the suction side when trying to read with the gauge.

I plan to finish my EPA certificate, then start with trying to recover the refrigerant and leak test with nitrogen. Then I’ll probably need advice!

GW

D box??? The indoor units don't go directly to the outdoor unit??

wmgeorge

GW and I wondered about the #8 wire and armored cable also? I have never installed a multi head or that brand so decided not to comment.  If he is talking about the OS unit that should be Sealtite or conduit. 

mthmlf84

GW said:

D box??? The indoor units don't go directly to the outdoor unit??

Correct it’s a 60K lg multi max system that can operate 2-8 indoor units. One outdoor compressor with 240v 8ga wire to 45a breaker——>14 4 comm/power cable, 3/4 suction copper and 3/8 discharge copper to distribution unit in the attic—->from there, 14/4 comm/power and 1/2 gas + 1/4 liquid lines to indoor units which each have their own wired remote and short run ducts.

mthmlf84

wmgeorge said:

GW and I wondered about the #8 wire and armored cable also? I have never installed a multi head or that brand so decided not to comment.  If he is talking about the OS unit that should be Sealtite or conduit. 

Sorry yes it’s conduit to the disconnect box then a liquid-tight armored 8 wire to breaker panel. Armored covered in grey rubber..

GW

Ok with Mits it’s not a cake walk to set up a d box system, gotta shuffle and wiggle a few dips and dials 

ayetchvacker

I’m starting to wonder if the appliance was empty when he got it. Where did you purchase this equipment from? Also kudos to you for looking into the EPA cert! 

pecmsg

Getting the EPS license is fine and dandy, but it still doesn't make you qualified to work on, or trouble shoot this highly complicated system. All 608 does is allow you to hook up gauges and purchase refrigerant. It does not make you qualafied to work on any equipment much less a Mitsubishi system. (Refrigerant can be bought on fleabay without a license)

How are you going to deal with tech support WHEN issues arise? They will know you're not a tech and wont deal with a homeowner.

Cut your losses, get a contractor on site to recover what refrigerant is remaining.
review the entire install.
Leak check the entire system
Proper pressure testing and evacuation.
Proper charging, start up and commissioning.

Then WHEN an issue arrives, they can talk to tech support.

wmgeorge

Correct EPA Cert does not make you qualified for HVAC work. I had office ladies in my classes that could not even put on a gauge set correctly. But they passed the test!

mthmlf84

wmgeorge said:

Correct EPA Cert does not make you qualified for HVAC work. I had office ladies in my classes that could not even put on a gauge set correctly. But they passed the test!

In a way, I’m an office lady but I don’t have EPA cert yet. Studying day 4 today. Also in my neck of the woods, i yet have to find a contractor that will agree to come and pull a vacuum or troubleshoot a system bought by a customer, especially since it’s an LG. The closest LG certified tech is an hour away and refuses to drive down to commission or install a unit, even for more money. The techs in my area, all Mitsubishi, are insanely busy putting in systems everywhere. Mitsubishi rolled out crazy rebate incentives that expire in late march or something, that drove demand, and there’s tons of people from the city who moved out here and started to remodel with their covid money. That’s why I’m in the situation I’m in and that’s why I’m trying to learn how these things work.

ratio

Ya know, at first I was gonna be a little snotty and list all the upfront expenditures necessary to do this job correctly, but then after thinking about it for a while, go for it! The truth is that experienced, qualified techs are not actually all that common, and can't always be bought for love or money when they do exist, as you've found out. Given that situation, there's not much else to do than to hitch up your britches & do it yourself. & like @ayetchvacker said, kudos to you for getting an EPA cert yourself—not a lot of DIYers would go that far to make it work.

WRT tech support, I'd first call them & see of they'll deal with you. If not, I'd raise a stink about their certified service personal refusing to service you, & you're just trying to do the right thing, esp mentioning the EPA cert.

The truth is, this isn't that hard to do, there's a lot of assistance out there (here? ). There is a large buy-in, like I mentioned above. I've worked in two trades now, and this is by far the more expensive one. You can make a decent go as an electrician with a few hundred dollars in hand tools, but you can't even start this job without dropping a few kilobucks, and that's without the nice does-it-for-you tools like a digital manifold.

wmgeorge

Well if that's the case get an real education in H&C not just on here or You Tube and go in business yourself! I have tried and tried to get local younger folks interested in the trade, I had perhaps 230 in my two year full time class over the 12 years I was teaching. All but one or two had jobs waiting when they left including 2 or 3 girls.
Added, we used the Delmar textbook for most of it, I will try to find a link to Amazon.

This is the textbook we used, and gee whiz the price has gone up! Get your EPA Cert and this book study as you go and learn the correct way to do stuff. Yes this is an expensive trade to get into, or in my case back into!! I started out in 1961 in the USAF as a Air Craft Electrician and when I got out took classes to become a electrician and that really helped a lot when I decided to switch to HVAC and took classes for that also.

https://www.amazon.com/Refrigeration-Conditioning-Technology-Bill-Whitman/dp/1401837654/ref=sr_1_15?crid=OS54JLVGJPLE&keywords=delmar+heating+air+conditioning+book&qid=1645390072&sprefix=delmar+heating+air+conditioning+book,aps,93&sr=8-15

ayetchvacker

Based on your current situation with the system flat (empty) here’s what needs to happen: 
recover refrigerant into a refrigerant recovery cylinder
pressure test system with nitrogen 
locate and repair leak (level of the repair will depend on where the leak is; ie bad flare vs. bad coil)
deep evacuation with micron gauge to prove proper vacuum
fill system with refrigerant 
This is what I would consider a high level process for repair and not something I would even send just any technician to do. I admire your ambition and in no way am I trying to discourage you. I’m only explaining the situation you’re in. 

You will need some training and quite a few more tools/equipment to pull this off. 

You mentioned you had a bottle of nitrogen. Have you tried pressurizing the system?

mthmlf84

hey guys thanks for all the info. I got the EPA cert now, and I definitely understand what you mean when you say some people don't know how to hook up a gauge after passing that. you learn things, but you learn there's a lot you don't know as well, and well, ok the stratosphere is 23 miles thick, whatever.

meanwhile I did get a bunch of tool, unfortunately most of them chinese trash from amazon, but they seem to all work and given that I don't know when I'll come across a good tech and given that well, I have more than one of those units, and now I'm too deep in to turn around. My service ports are 5/16, I got valve core removers for that, tees, a cheap digi gauge, a leak detector, a recovery machine, nitrogen with an amazon manifold, leak bubbles, a scale, a recovery tank and some extra r410a




There's no trace of oil at any of the flares. I tried recovering refrigerant from the system earlier and there really is no pressure in there at all from the start, so I didn't want to let it go into vacuum because it seems like there's obviously a leak and trying to achieve vacuum would suck in oxygen into the lines even more and into the recovery tank (maybe not such a big deal since it's empty but still).

I'm now going to try and pressure test with N2 and bubbles.

wmgeorge

My gas line port was 1/4 inch. I do not think R410a carries the oil like R12. Are you 100% sure the service ports are open all the way CCW and then when your gauges are on the Schrader's crack it back 1/16 turn CW. The only flaring tool I have is the Rol Air one, makes the flare above the flaring block, I have never had an issue with flare leaks.

mthmlf84

the rol air one looks nice! I nitrogen purged a little bit and am now leak testing like I should have done the first time. started with 50 psi because I know there's a leak, lost 20 psi of nitrogen over just an hour. found a few leaks already, most of which I corrected. mostly on 1/4 lines, a lot of them weren't torqued to spec at all! way looser than they were supposed to be, 6 ft lbs ish instead of 14-19, ridiculous. lots of them fixed. continuing. starting to have hope that the main problem (aside from stupidity) was just loose flare fittings and that I lost all my refrigerant through that before even turning the system on the first time. that would be really nice.

mthmlf84

lg has this annoying thing too where the ditribution box is 3/8 1/4 and the units have 1/2 1/4 and they come with reducers, so you have to go from a 3/8 line from the box and enlarge into a 1/2 when come into the unit, which creates one more possiblity of something leaking.

wmgeorge

Ok here is what I did on flares, when I worked in the supermarket end, always used Leak Lock on flare nut threads attached to the leaving side of TXVs because of the temp swings in a refrigerated case. I used Blue Locktite on my HP flare threads same reason. 
Used refrigeration oil on the back side of the flare nut copper tube. 
Only leak was on a factory flare on liquid line, cracked. 
They sell something now Blu something like a heavy oil for flares. I'd need to find it tomorrow in the shop. 

pecmsg

Nylog is superior to leak loch. A drop on the back where the nut pressure on the copper   And a drop on the flair faces. 

All nylog is is very thick oil. 

wmgeorge

pecmsg said:

Nylog is superior to leak loch. A drop on the back where the nut pressure on the copper   And a drop on the flair faces. 

All nylog is is very thick oil. 

The gas line goes from hot to cold and the temperature swings cause the nut to loosen. In commercial refrigeration work flare nuts on TXVs always loosen, in those days we used Leak Lock on those flares to stop the problem. If you have never worked on supermarket or other freezer or cooler refrigeration you will not know. I used Blue Locktite on the threads because I know it works. Behind and on the flare oil or the Nylog stuff.

I would silver braze or Silphos the fittings IF I could, flares have no place on R410a or fittings than are subject to both heat and cold.

pecmsg

The temperature swings don’t cause the nut too loosen the moisture getting in there freezing and stretching the nut does. Nylog doesn’t allow the moisture to get in there. X-Valve flair nuts have holes or slots too allow for this expansion. 

Leak lock did the same thing but does dry out over time. 

wmgeorge

pecmsg said:

The temperature swings don’t cause the nut too loosen the moisture getting in there freezing and stretching the nut does. Nylog doesn’t allow the moisture to get in there. X-Valve flair nuts have holes or slots too allow for this expansion. 

Leak lock did the same thing but does dry out over time. 

When does a heat pump have freezing on the gas line?

I used Leak Lock and never had a call back on commercial calls. Temperature heat to cold causes those issues even on medium temp equipment, I ran service for over 25 years.

pecmsg

BS
Everyone makes mistakes, That’s how we learn!

pecmsg

On Minis both lines are suction

wmgeorge

pecmsg said:

On Minis both lines are suction

Hmm the Liquid line is always liquid either feeding the indoor coil in the AC mode or returning the condensed liquid in the liquid line in the Heating mode. The gas line is either cold in the line returning from the indoor coil in the AC mode or hot feeding the indoor coil in the heating mode. Very much temperature change in that gas line. As you know the reversing valve only changes the gas line in a heat pump. Temperature changes cause the flare nuts to loosen. Hence the Locktite on the threads. Simple expansion and contraction.

pecmsg

The metering device is in the outdoor section. The small line is low pressure liquid and frosts. 

wmgeorge

pecmsg said:

The metering device is in the outdoor section. The small line is low pressure liquid and frosts. 

Never. To help you understand I have attached the flow diagram, The Liquid does not frost its warm or cool unless its a charge issue. The Stop valves are the ones on the outside unit.

ratio

I've seen some 'mini splits' with the expansion device in the indoor unit, but many (most?) have it in the outdoor unit. Mitsubishi, for example, on all the models that I've worked on so far (excepting VRF systems with branch boxes), have an EEV in the outdoor unit. While the mixed-phase (AKA liquid) line shouldn't be frosty unless something's wrong, it'll condense just like a suction line.

I think of it as part of the evaporator.

pecmsg

wmgeorge said:

The metering device is in the outdoor section. The small line is low pressure liquid and frosts. 

Never. To help you understand I have attached the flow diagram, The Liquid does not frost its warm or cool unless its a charge issue. The Stop valves are the ones on the outside unit.

And what’s to the right of the small line? A cap tube metering device. As such that makes the small line the suction line in cooling!