Mini split recharge

[coolguy4]

Hello everyone, I installed a Pioneer 12K BTU 21.5 SEER inverter mini split heat pump last spring to heat and cool my house. It has been running great all summer, but now that it is cold outside and I switched to heat mode I started running into issues with defrost. Long story short, I determined that the shrhrader valve is bad and is leaking refrigerant. I called their support and they told me since I do not have refrigerant or a recovery machine I can call an HVAC company out to fix the unit and they will refund me 75% of the total bill since it is under warranty, so I will only have to pay around $50. Cool!

I have a couple questions though.

1. According to the owners manual, the unit is charged for a 16’ line set, but is good up to 25. It also says to add 0.16 ounces of refrigerant for every foot of lineset beyond 16 feet if above 25. So since I Installed a 25’ lineset and I will have to have it recovered and recharged anyways since the refrigerant could be fractionated, should I request that the tech adds an extra 1.4 ounces of refrigerant to get the charge perfect for the lineset, or have it charged to the factory spec for 16 foot lineset since it’s good up to 25? It would seem like it would be ideal to add 1.4 ounces extra to compensate for the longer lineset, but I am not an expert.

2. Since this is an inverter mini split, from my understanding the only way they can be charged accurately is by weight and that charging by pressure alone isn’t’ accurate. Is that correct? The tech support guy told me it can be accurately topped off by pressure, but I don’t see how that could be done on a system with 1 service port and variable speed compressor.

Thank you very much in advance, I really appreciate your help.

[Tycho]

Well to fix the leak they will have to empty the charge.

1. I would have them weigh how much they take out of the system when they empty it. that way you will know how much has been lost from the original factory charge

fix the leak, pressure test, vacuum it...

Recharge by weight, and add the extra 1.4 oz to bring it up to proper specs.

2. you are correct, charging by pressure is possible, but it it would be correct only under the exact running conditions you have on that day. Charging by pressure works on small coldrooms that will run under the same conditions all year, not on Inverter AC units.
So charge by weight

[coolguy4]

Well to fix the leak they will have to empty the charge.

1. I would have them weigh how much they take out of the system when they empty it. that way you will know how much has been lost from the original factory charge

fix the leak, pressure test, vacuum it...

Recharge by weight, and add the extra 1.4 oz to bring it up to proper specs.

2. you are correct, charging by pressure is possible, but it it would be correct only under the exact running conditions you have on that day. Charging by pressure works on small coldrooms that will run under the same conditions all year, not on Inverter AC units.
So charge by weight

Thank you for your help, I really appreciate it. The guy came out to recover the refrigerant, change the leaky schrader valve, and recharge with fresh refrigerant and the unit seems to be running well now. I have a couple more questions though.

1. When the man charged the unit, he obviously had to charge the refrigerant as a liquid so it doesn’t fractionate. However, what he did was he added as much liquid as he could (a little over 2 pounds) to the suction line before starting the unit in AC mode to finish charging the unit. Is it not bad on the compressor to dump 2 pounds of liquid refrigerant into the suction side and then start it in cool mode? The guy said it will go right through the compressor and do no harm, but he would dump it in the liquid line if it had a port. It didn’t seem to do any damage, but I have always thought that doing that will force liquid refrigerant through the compressor and could damage it since it can’t compress liquids? Am I correct?

2. When I took the panel off the unit to check the outdoor coil temp sensor when the company asked me to check its resistance, I noticed that the compressor has no blanket around it. I confirmed with the company that this unit should have an insulation blanket around the compressor to reduce noise, but the didn’t know if it was important. Is the insulation blanket important? I really don’t care about noise because I installed the outdoor unit next to my attached garage (away from the house) and it runs quiet enough anyways. But since this unit is the ultra low ambient version, the compressor has a crankcase heater. I am wondering if the insulation blanket is needed to hold the heat in so the compressor stays warm.

Thanks again in advance, I really appreciate your help!

[Tycho]

Thank you for your help, I really appreciate it. The guy came out to recover the refrigerant, change the leaky schrader valve, and recharge with fresh refrigerant and the unit seems to be running well now. I have a couple more questions though.

1. When the man charged the unit, he obviously had to charge the refrigerant as a liquid so it doesn’t fractionate. However, what he did was he added as much liquid as he could (a little over 2 pounds) to the suction line before starting the unit in AC mode to finish charging the unit. Is it not bad on the compressor to dump 2 pounds of liquid refrigerant into the suction side and then start it in cool mode? The guy said it will go right through the compressor and do no harm, but he would dump it in the liquid line if it had a port. It didn’t seem to do any damage, but I have always thought that doing that will force liquid refrigerant through the compressor and could damage it since it can’t compress liquids? Am I correct?

2. When I took the panel off the unit to check the outdoor coil temp sensor when the company asked me to check its resistance, I noticed that the compressor has no blanket around it. I confirmed with the company that this unit should have an insulation blanket around the compressor to reduce noise, but the didn’t know if it was important. Is the insulation blanket important? I really don’t care about noise because I installed the outdoor unit next to my attached garage (away from the house) and it runs quiet enough anyways. But since this unit is the ultra low ambient version, the compressor has a crankcase heater. I am wondering if the insulation blanket is needed to hold the heat in so the compressor stays warm.

Thanks again in advance, I really appreciate your help!

1. my experience on Split AC units are limited, the ones I have done for family and friends had 2 service ports, and the only one I have had to reclaim, pressure test and recharge is my own. Turned out it had a hairline crack on the flare connection on the suction line that started leaking after 10 years

Remember that the entire system is under deep vacuum when he charges the initial amount of liquid, so a lot of it will flash and turn to gas.

Don't know what kind of compressor is on your unit, I'm guessing Scroll, and they can handle liquid.
https://www.youtube.com/watch?v=YNeoFebbU6I

if it's not a scroll, then the compressor itself is suspended inside the shell and the suction line is only connected to the shell, basically making the shell a suction accumulator.

I don't see any harm in the way he did it. The compressor can take it and it was really the only option he had.

On my split unit, I dumped the primary charge into the liquid line, but I still had to charge the remaining charge (in liquid form), through the suction line, and then.

2.I would say that if the unit is sold as an "ultra low ambient version" then the blanket is indeed a crucial part, and it should also have a proper heating element fixed in the outdoor unit drip tray.

Like they said, the blanket serves two purposes, noise damping and keeping the compressor warm.

The crank case heater, is it around 1/2" in diameter, 1" long, plonked into a hole in the side of the compressor near the bottom?
If the crankcase heater is sitting fairly loose in that hole (if you wiggle the wires, does the heater move/rattle), I would pull the heater out, get some contact/thermal paste into the hole before jamming the heater back in.
If there is no contact between the heater and the metal, then it's just heating up the surrounding air, and only a few % of the energy it's pulling is going to actually warm up the compressor. depending on the size it may only be pulling the equivalent of a lightbulb or two, but you are paying for it


I did some googling, and if I found the correct manual, then your unit, being the Arctic model should be able to handle -15C (5F) and then the blanket should definitely be on the compressor.
Attachment 15455

So if it isn't there I would call them up and have them send one over... preferably along with a service technician to install it

I can see you are in the US, but not what part, so I don't know what the lowest ambient temperatures will be in your parts.

However, I live in Norway, on the coast, so ambient temperatures around here rarely drops below -5C (23F). When I bought my AC in 2002, the supplier said that the blanket should be enough unless the temperature dropped below -10 (14F), if I expected it to drop below that, they recommended I buy a "winter upgrade kit".

The "winter upgrade kit" was 6 feet of wobbly self-regulating heating cable and a klixon thermostat.

I asked them what it was for, and it was for the drip tray on the outdoor unit to prevent ice buildup.

So I laid down as much as I could fit in the drip tray, stuck it in place with aluminum tape, and when I was done I had three feet left over, so I undid the blanket around the compressor, wound the remaining heating cable around it, put the blanket back on, attached the thermostat and connected it to the terminals as instructed.

Funny thing is that we were 14 guys, all of us working in the same refrigeration company who ordered split AC units at the same time (better price for high volume order).
Mine is the only one still running Kind of proud

I have had two issues, first was the fan on the indoor unit that was getting noisy.
I didn't notice until I had friends over, we were talking and I had to say "You have to speak up, the AC is running!"
So I called the wholesaler and claimed the fan motor on the indoor unit, they said no problem and they would send me one post haste... I got two... When I called them and asked why they had sent me two fan motors they said... and get this "Well, in case the one you put it fails prematurely, you will have one in spare ready to go" All I could say was "ok..thank you"

The next issue I had was the hairline crack in the flare connection (my fault).

The way I discovered that the AC had a low charge was during a particular warm summer.
The outdoor temperature had soared to a baking 25C (77F) for over a week and naturally I had set my AC to 16C (60F) and cooling to maintain a cool 18C (64F) indoors.

I was lounging on the couch, unable to function in the pressing heat, must have been 22C (71F) ... I hear a *click psssssh* from the AC then maybe 10 seconds later I'm standing on the couch as someone is shooting at my house with a machine gun... Fight or flight reflex is trying to determine which way to run or attack...

Then I notice Ice cubes shooting out of my indoor unit.

I shut it down, open the lid, and the whole evaporator was frozen solid



Not bad, you got an explanation, and a (to me) funny story to boot :P

[coolguy4]

1. my experience on Split AC units are limited, the ones I have done for family and friends had 2 service ports, and the only one I have had to reclaim, pressure test and recharge is my own. Turned out it had a hairline crack on the flare connection on the suction line that started leaking after 10 years

Remember that the entire system is under deep vacuum when he charges the initial amount of liquid, so a lot of it will flash and turn to gas.

Don't know what kind of compressor is on your unit, I'm guessing Scroll, and they can handle liquid.
https://www.youtube.com/watch?v=YNeoFebbU6I

if it's not a scroll, then the compressor itself is suspended inside the shell and the suction line is only connected to the shell, basically making the shell a suction accumulator.

I don't see any harm in the way he did it. The compressor can take it and it was really the only option he had.

On my split unit, I dumped the primary charge into the liquid line, but I still had to charge the remaining charge (in liquid form), through the suction line, and then.

2.I would say that if the unit is sold as an "ultra low ambient version" then the blanket is indeed a crucial part, and it should also have a proper heating element fixed in the outdoor unit drip tray.

Like they said, the blanket serves two purposes, noise damping and keeping the compressor warm.

The crank case heater, is it around 1/2" in diameter, 1" long, plonked into a hole in the side of the compressor near the bottom?
If the crankcase heater is sitting fairly loose in that hole (if you wiggle the wires, does the heater move/rattle), I would pull the heater out, get some contact/thermal paste into the hole before jamming the heater back in.
If there is no contact between the heater and the metal, then it's just heating up the surrounding air, and only a few % of the energy it's pulling is going to actually warm up the compressor. depending on the size it may only be pulling the equivalent of a lightbulb or two, but you are paying for it


I did some googling, and if I found the correct manual, then your unit, being the Arctic model should be able to handle -15C (5F) and then the blanket should definitely be on the compressor.
Attachment 15455

So if it isn't there I would call them up and have them send one over... preferably along with a service technician to install it

I can see you are in the US, but not what part, so I don't know what the lowest ambient temperatures will be in your parts.

However, I live in Norway, on the coast, so ambient temperatures around here rarely drops below -5C (23F). When I bought my AC in 2002, the supplier said that the blanket should be enough unless the temperature dropped below -10 (14F), if I expected it to drop below that, they recommended I buy a "winter upgrade kit".

The "winter upgrade kit" was 6 feet of wobbly self-regulating heating cable and a klixon thermostat.

I asked them what it was for, and it was for the drip tray on the outdoor unit to prevent ice buildup.

So I laid down as much as I could fit in the drip tray, stuck it in place with aluminum tape, and when I was done I had three feet left over, so I undid the blanket around the compressor, wound the remaining heating cable around it, put the blanket back on, attached the thermostat and connected it to the terminals as instructed.

Funny thing is that we were 14 guys, all of us working in the same refrigeration company who ordered split AC units at the same time (better price for high volume order).
Mine is the only one still running Kind of proud

I have had two issues, first was the fan on the indoor unit that was getting noisy.
I didn't notice until I had friends over, we were talking and I had to say "You have to speak up, the AC is running!"
So I called the wholesaler and claimed the fan motor on the indoor unit, they said no problem and they would send me one post haste... I got two... When I called them and asked why they had sent me two fan motors they said... and get this "Well, in case the one you put it fails prematurely, you will have one in spare ready to go" All I could say was "ok..thank you"

The next issue I had was the hairline crack in the flare connection (my fault).

The way I discovered that the AC had a low charge was during a particular warm summer.
The outdoor temperature had soared to a baking 25C (77F) for over a week and naturally I had set my AC to 16C (60F) and cooling to maintain a cool 18C (64F) indoors.

I was lounging on the couch, unable to function in the pressing heat, must have been 22C (71F) ... I hear a *click psssssh* from the AC then maybe 10 seconds later I'm standing on the couch as someone is shooting at my house with a machine gun... Fight or flight reflex is trying to determine which way to run or attack...

Then I notice Ice cubes shooting out of my indoor unit.

I shut it down, open the lid, and the whole evaporator was frozen solid



Not bad, you got an explanation, and a (to me) funny story to boot :P

Thank you for all the great info, I really appreciate it. I gave you positive rep.

I don't know what type of compressor this unit has, it's not listed anywhere on their website or in the specs. However, it's a round can rather than an oval, so I know it's not a reciprocating compressor. Either a scroll or rotary compressor I guess. I'm glad to know that liquid won't damage a scroll compressor though, I didn't know that. I thought any significant amount of liquid in any compressor had a potential to kill it, but as I said I'm not an expert.

My low ambient unit is good down to 5 degrees F (-15 C) in cooling mode and -14 degrees F (-25 C) in heating mode, their standard unit is good down to 32 degrees F (0 C) in AC mode and 5 degrees F (-15 C) in heating mode.

As for the crankcase heater, it's just a metal band that's clamped around the bottom of the compressor. Since it's clamped directly to the compressor, I suppose it's keeping it warm just fine. My unit also came with a base pan heater. I live in the Memphis area, so I'm not as concerned about cold as I am heat. The unit runs all night heating the house, so I presume the compressor is staying plenty warm. The unit doesn't get shut off for long periods of time in cold weather, and it usually doesn't get below 20 degrees F here, or like -6 degrees C. For that matter the unit basically runs constantly since it's a variable capacity inverter unit. Heating season is only a few months of the year here, the rest is cooling season.

However, I am wondering if it might be a benefit to not have insulation around the compressor here since this unit is mostly used for cooling and it gets so hot here (100+ degrees F, 38+ degrees C.) I know that the compressor is primarily cooled by the cold refrigerant vapor running through it, but I'm sure the case of it also dissipates some of the heat, and insulation would prevent that. I don't know how big the difference in compressor oil and/or discharge temp would be, maybe a few degrees? So I am wondering if it might not be better for the unit's cooling performance and longevity to not have insulation around the compressor in this climate. Any thoughts on this? Thanks