One line icing up

[darcyh]

Hi Guys:

We have a LG 9K unit where the compressor is located outside and runs to a blower unit in the bedroom. Although the unit runs ok it sure takes a long time to cool the room.

The rest of the house is on a central air unit. The previous owner wanted to have independent control of the temp in the bedroom, hence the little LG unit.

I see two lines going into the compressor and one is covered with frost or ice, the other line is slightly warm. The frost appears on the uninsulated part of the line (about 2 inches) where it enters the compressor.

I have cleaned the coils and filter on the inside unit (they were not very dirty) as well as the outside unit.

This is the first year we have been in the house so I cannot compare to past performance.

All blower motors operate normally. Unit is about 10 years old.

Is the icing / frost on the small exposed portion of the line normal?

Thanks very much.

Dave

 

[brewchief]

The icing is indicative of low refrigerant level or lack of airflow, since you have already cleaned the filter and say the blower is operating normally I would say it is low on refrigerant, time for a service call. Since you have no prior history it could be a leak or could have been low since new, I would have the tech charge the unit and do a basic leak check on the service caps and the lineset fitting if they are flare connections(they should be), I wouldn't do a more extensive leak search until I knew for sure it was leaking.

 

[lzenglish]

Mini spits are a little differant, in that most of them have the metering device in the condensing unit itself, as opposed to the inlet of the evaporator, which was always the norm, for a split systems. The indication of "Frost" means that the liquid temp in the refrigerant line has reached the dew point of the ambient conditions in the surrounding space. It sounds to me like the unit is low on charge, and needs a little refrigerant added to it. Put the gages on it, and it should read in the neighborhood of 60-70 psig, on the low side and 250-275psig on the high side with an outside ambient temp of 80-90 degrees F., with R-22 refrigerant. Also, you should have around a 20 degree split, from the return air, and the supply air. These are ballpark pressures, and will vary, as to the condition of the evaporator coil restricions (plugged filter,ect.), and a dirty condensor, ect.

Wayne

 

[pseudorealityx]

If it's a recent mini-split, it's likely not R-22 and more likely R-410a.

That will throw off the pressure numbers that Wayne gave you, but he explained it well.

 

[lzenglish]

If it's a recent mini-split, it's likely not R-22 and more likely R-410a.

That will throw off the pressure numbers that Wayne gave you, but he explained it well.

Absolutly true, as I still have R-22 on the brain! If it is another refrigerant, then I appoligize for giving you the wrong anwser, but the same general concept stll holds true. I need to bone up on the newer refrigerant propertirs, before I answer another question invoiloing the same refrigerant!

Wayne

 

[danski0224]

Mini spits are a little differant, in that most of them have the metering device in the condensing unit itself, as opposed to the inlet of the evaporator, which was always the norm, for a split systems. The indication of "Frost" means that the liquid temp in the refrigerant line has reached the dew point of the ambient conditions in the surrounding space. It sounds to me like the unit is low on charge, and needs a little refrigerant added to it. Put the gages on it, and it should read in the neighborhood of 60-70 psig, on the low side and 250-275psig on the high side with an outside ambient temp of 80-90 degrees F., with R-22 refrigerant. Also, you should have around a 20 degree split, from the return air, and the supply air. These are ballpark pressures, and will vary, as to the condition of the evaporator coil restricions (plugged filter,ect.), and a dirty condensor, ect.

Wayne

I have yet to see a mini-split with 2 gauge ports.

Mini-split system pressures do not correspond to typical residential split systems.

The quoted info above will not apply to a typical mini-split system.

If you have a mini-split that isn't working, best thing to do is evacuate and recover the refrigerant charge, then weigh it. At this point, you will know if it was properly charged with refrigerant.

Weigh in new refrigerant based on manufacturer info and lineset length.

Do NOT add sight glasses or filter driers unless the manufacturer allows it.

If the system still does not work, do not call just anyone to fix it.

 

[JimL]

I have yet to see a mini-split with 2 gauge ports.

Mini-split system pressures do not correspond to typical residential split systems.

The quoted info above will not apply to a typical mini-split system.

If you have a mini-split that isn't working, best thing to do is evacuate and recover the refrigerant charge, then weigh it. At this point, you will know if it was properly charged with refrigerant.

Weigh in new refrigerant based on manufacturer info and lineset length.

Do NOT add sight glasses or filter driers unless the manufacturer allows it.

If the system still does not work, do not call just anyone to fix it.

Mitsubishi units have a high side port inside them. Only leak issues I have ever had were at flare connections. Charging them, I do it out of the charging chart in the service manual.

 

[lzenglish]

Mitsubishi units have a high side port inside

What psig of suction and discharge pressures would you expect to see, with an O.A of 85-90, on a R410a system? With a clean condenser, and un-restricted evaporator coil, of course?

Thanks,

Wayne

 

[JimL]

what model outdoor unit? inverter? Non inverters run 310-320 on the high side, 125-130 on your suction side. Just charged one yesterday.

 

[lzenglish]

Thanks JimL!

Wayne

 

[darcyh]

Thanks for the advice. It's appreciated.

I removed the cover inside to double check that the cooling coils was not plugged up with dust. It is clean. I also noticed frost building up on the left side of the cooling coil, and the coil was not nearly as cool on the right side. Is this connected to the frost build up on the outside line.

Unit uses R22 and there appears to be 2 capped connections where the line enter the outside unit.

Can I add freon myself? Sticker on side of outside unit says high pressure 350 and low is 150. Unit was made in 2003.

Thanks very much

Dave

 

[lzenglish]

Thanks for the advice. It's appreciated.

I removed the cover inside to double check that the cooling coils was not plugged up with dust. It is clean. I also noticed frost building up on the left side of the cooling coil, and the coil was not nearly as cool on the right side. Is this connected to the frost build up on the outside line.

Unit uses R22 and there appears to be 2 capped connections where the line enter the outside unit.

Can I add freon myself? Sticker on side of outside unit says high pressure 350 and low is 150. Unit was made in 2003.

Thanks very much

Dave

Sounds like you do have an R-22 unit. The capped lines are probably the high and low side, or suction and discharge ports, which is the same thing. You will need a set of gages, and the color code will be high side red, low side green. Remember, the EPA defines a A/C Tech, as "anyone" working on a charged system, so by law, you should have a recovery unit on site. Hook the gages up,(if you feel comfortable doing so), and add some refrigerant if needed. Always charge with vapor on the low side, and look for the pressures I gave you, in a previous post.

Wayne

 

[pop pop]

If the OP doesn't know which ports to charge he should defer to someone who knows. Too much danger for an amature here. Even if successful he'll likely introduce air without knowing to "burp" the gageset.

 

[lzenglish]

If the OP doesn't know which ports to charge he should defer to someone who knows. Too much danger for an amature here. Even if successful he'll likely introduce air without knowing to "burp" the gageset.

I agree with you to a certain extent "pop pop"! All I'm trying to do, is to help out a person who wants, and or needs help! There are so many so called A/C, and or Refrigeration Contractors, and service techs.out there that know nothing more then how to write up a high estimate and parts change a person to death! IMO

Wayne

 

[darcyh]

Thanks for all the suggestions (especially Wayne). I got an AC guy in yesterday and he checked the unit over, could not find any leaks. He added dye and 18 oz of R22.

He also checked over the main AC unit; pressures were fine, he suggested the contact assembly was getting pitted and said I could wait or he could change it. I had him change it. He was here about an hour and charged me $152 including the freon and contact unit.

The little LG is running fine now.

I figure the price he charged was reasonable.

Thanks again.

Dave

 

[Falcon67]

That's way, way, way reasonable.

 

[lzenglish]

Thanks for all the suggestions (especially Wayne). I got an AC guy in yesterday and he checked the unit over, could not find any leaks. He added dye and 18 oz of R22.

He also checked over the main AC unit; pressures were fine, he suggested the contact assembly was getting pitted and said I could wait or he could change it. I had him change it. He was here about an hour and charged me $152 including the freon and contact unit.

The little LG is running fine now.

I figure the price he charged was reasonable.

Thanks again.

Dave

Sounds Like a Deal Dave! Glad you are up and running!

Wayne