# copper tube not "cold"



## noquacks (Jun 5, 2010)

Hi people,

have an ac system- condenser/comp unit is on top of a high rise condo, so havnt gone up there yet. But inside the condo, no cold air blowing. I did notice that the low pressure copper line (thicker one, right?) is not cold to touch, but the thin line (high pressure line?) is. 

Now, last night, went to bed, system ran for hours without stopping. Woke up, say, 2AM, shut the whole thing down after seeing it wasnt blowing any cold, and simultaneously noticed the low line was ambient, and high line was iced up!. Should this probably be low refrigerant? Why is high line iced up and no cold ac, people?

(PS: Once I get some direction from the fellow members here, I am prepared to climpb up to the sky to get to the unit, and get yous some pressure readings, if advised)
Thanks!


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## yuri (Nov 29, 2008)

Iced up means low on refrig or lack of airflow from dirty filters or dirty coil in the air handler/fan unit. DO NOT keep running it that way or liquid refrig will damage your compressor. Should get a Pro to check the freon level etc. Filters you can DIY and if the coil is dirty and accessible you may be able to clean it but it is a nasty difficult job and not for everyone.


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## noquacks (Jun 5, 2010)

yuri said:


> Iced up means low on refrig or lack of airflow from dirty filters or dirty coil in the air handler/fan unit. DO NOT keep running it that way or liquid refrig will damage your compressor. Should get a Pro to check the freon level etc. Filters you can DIY and if the coil is dirty and accessible you may be able to clean it but it is a nasty difficult job and not for everyone.


Thanks, yuri for the reply and advice. I should have mentioned I did check the filter and it was clean, actually, remembered that I had replaced it not long ago- its like new. Cleaned coil a few yrs ago (never been cleaned for 25++ yrs before that), FULL of pet hairs/ppeople hairs/crud/junk/goo- what a disgusting mess, but I did it!

Now, professional- why cant I put guages on it and check for refrigerant/pressures? What are typical psi's? Im willing to try.......


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## yuri (Nov 29, 2008)

there are no typical pressures as I/we need to know the load on the machine, amount of airflow, outdoor and indoor temps, humidity, cleanliness of indoor and outdoor coil, age of compressor(worn valves) and a few other factors to get proper pressures. anyone who tells you otherwise is guessing and you may as well use the beer can cold method. you can post that info and we can narrow it down but not do it properly. low on freon will cause your elec bills to go higher so getting a Pro will make it more efficient if that is important, nothing against DIY but it is not as simple as it sounds.


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## noquacks (Jun 5, 2010)

good deal, yuri. heck, I will at least crawl under the coils again to clean out/inspect if reqd. Maybe dog hair got to it again. I know filter is good, so cleaning coil again is only thing left to do as a diy.

Thanks


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## yuri (Nov 29, 2008)

Yep, dog hair is nasty so you need to shut off the unit, let it defrost and dry out and clean the coil, simple green spray cleaner and plenty of clean water to flush it works OK. I find those round and rectangle brushes that go on the end of vacuum cleaner hoses to work well even w/o that vacuum on if necessary. I use them on a shop vac and they are soft and don't damage the coil fins. Good Luck.


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## Tator1076 (Dec 22, 2009)

It can be low on freon, dirty coil,dirty filter,vents block off, cooling txv closed down and fan blower problem.


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## noquacks (Jun 5, 2010)

Update: Cleaned the crud from under the coils- geez, good thing this doesnt need to be done every 30 days...LOL

While I dont regret this cleaning (it needed it bad), it didnt solve the cooling problem,so I said, lemme go up to the roof and check pressure on ow side- geez, it had only about 10-12 lbs! Now, fan runs well, filter clean/new, coils cleaned out, so either TEV or refrigerant low, right people?


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## yuri (Nov 29, 2008)

Yep...


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## thermal-medics (Feb 11, 2012)

*just checkin*

Hey,

just wondering.

1.on your first post you said the suction line (thick one) was warm and the liquid line (small one) was frozen right?

2. You are operating the unit in cooling mode?

3. Is the unit a heat pump or straight cool, with a gas furnace or floorboord heat or something like that??

If you are getting ice on the liquid line than we are talking about something totally different. Low charge, low airflow (dirty coil, fan motor intermittent or off-line) will cause a suction line (big one) to freeze all the way back to the compressor but if you are in cool mode and have a frozen liquid line I would be looking at the liquid line from the condenser coil downstream through the filter/drier for an obstruction. If you can trace the liquid line ( i know thats tough) you should find a pipe that is warm if not hot to the touch and then at some point you will see the ice. that is where the obstruction is. the obstruction is acting like a txv or orifice and the refrigerant is backing up in the condenser. a subcooling check would also tell the story. this is all assuming you are operating in cool mode.

if it is a heat pump try this, run it in heat mode if possible (and check out the pipes) for a few minutes then back in cool and see if your problem returns. If its not to hot out (i dont know where you are) than it wont be a problem.

good luck


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## thermal-medics (Feb 11, 2012)

*just checkin*

Hey,

just wondering.

1.on your first post you said the suction line (thick one) was warm and the liquid line (small one) was frozen right?

2. You are operating the unit in cooling mode?

3. Is the unit a heat pump or straight cool, with a gas furnace or floorboord heat or something like that??

If you are getting ice on the liquid line than we are talking about something totally different. Low charge, low airflow (dirty coil, fan motor intermittent or off-line) will cause a suction line (big one) to freeze all the way back to the compressor but if you are in cool mode and have a frozen liquid line I would be looking at the liquid line from the condenser coil downstream through the filter/drier for an obstruction. If you can trace the liquid line ( i know thats tough) you should find a pipe that is warm if not hot to the touch and then at some point you will see the ice. that is where the obstruction is. the obstruction is acting like a txv or orifice and the refrigerant is backing up in the condenser. a subcooling check would also tell the story. this is all assuming you are operating in cool mode.

if it is a heat pump try this, run it in heat mode if possible (and check out the pipes) for a few minutes then back in cool and see if your problem returns. If its not to hot out (i dont know where you are) than it wont be a problem.

good luck


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## noquacks (Jun 5, 2010)

thermal-medics said:


> Hey,
> 
> just wondering.
> 
> ...


Hmm, thanks, therm. To answer: 
1) correct-liquid line frozen (near the air handler)
2) cooling mode- Im in florid
3) no gas furnace, or floorboard heat/etc. Im pretty sure its a heat pump

Dang- that liquid line (as well as the suction line) travels together through some sort of chute through the floors of the condo building. Im sure this set up makes it hard to trace this . All I can do is acces/touch it from air handler unit back to about 2-3', then on the roof from comp down to where it meets the roof. After that- it dissappears into the bowels of the condo structure.


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## noquacks (Jun 5, 2010)

thermal-medics said:


> Hey,
> . Low charge, low airflow (dirty coil, fan motor intermittent or off-line) will cause a suction line (big one) to freeze all the way back to the compressor but if you are in cool mode and have a frozen liquid line I would be looking at the liquid line from the condenser coil downstream through the filter/drier for an obstruction. If you can trace the liquid line ( i know thats tough) you should find a pipe that is warm if not hot to the touch and then at some point you will see the ice. that is where the obstruction is. the obstruction is acting like a txv or orifice and the refrigerant is backing up in the condenser. a subcooling check would also tell the story. this is all assuming you are operating in cool mode.
> 
> if it is a heat pump try this, run it in heat mode if possible (and check out the pipes) for a few minutes then back in cool and see if your problem returns. If its not to hot out (i dont know where you are) than it wont be a problem.
> ...


Now, when I said liquid line was frozen/v cold, the coils were NOT frozen. Suction line also , like I said, was not frozen at all. Thats why Im mystified.

The air handler is new as of about 2000 or so, if that helps.


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## thermal-medics (Feb 11, 2012)

*on roof*

if you can on the rooftop, see if you can follow the liquid line out of the building back to the condenser coil and find the liquid line filter dryer. Note where the frost stops. if you have a restriction in the line(water, shavings, goop or compbination therof) then were it stops will be it. the indoor (evaporator coil) is being starved of refrigerant and its all backing up in the condensor coil. you will get a super low pressure on the low side and maybe even a vacuum as the compressor is sucking like crazy on it. 

If you have a heat pump or can run the heat for a spell do so and you will reverse the refer and could dislodge the restriction but it is nonetheless still there. If it is the filter/dryer than the system can probably be pumped down and it can be changed out thus saving you a pile in having to get a new dose of R-22 (BTW it just jumped in AZ to $325 a jug at the supply house!!!).

anyway let us know if you can find where the frost stops if you have access to the rooftop or if its too dangerous or a pain I would run it in heat for a couple of minutes then back to cool.


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## noquacks (Jun 5, 2010)

Thnaks, therm. Good plan- I will run the heat for maybe 10 minutes?? 15? Then try the cool after say, 10 minutes from switching? 

I can get on the roof no problem, and inspect the filter dryer (is that the goofy "can" welded to the liquid line, about 12-15" from the condenser?

Might have to wait a few days for this though- Im not there on weekdays usually. But no prob- I can check back here to advise.......


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## noquacks (Jun 5, 2010)

Oh, how many lbs does a 2 ton unit take?


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## thermal-medics (Feb 11, 2012)

*thats it*

thats the one. looks just like a can that has the liquid line running in/out of each end. should be a bi flow in a heat pump so the refrigerant can travel both ways but any tech will tell you a story of a single flow put in a heat pump or with flow arrow pointed the wrong way. I caught one of mine right before lighting the torch....


on the heat mode you dont need much just a couple of minutes - if it is too warm out it is not good for the system and often has a hi-pressure switch that will cut it off as a safety. 

the filter/dryer is just a spot that can be suspect the other is the outdoor metering device but it dosent matter you just want to know where the frost stops. 

At some point you will need an EPA certified tech out to deal with it since it unfortunately has to do with refrigerants. The heat trick has worked in the past for me a few times and thats an easy DIY. 

Take it ez climbing up/onto the rooftop and good luck!!!


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## thermal-medics (Feb 11, 2012)

*refer amount*

not sure how much refrigerant your unit holds. There will be a nameplate on the condenser with that info and then some is added due to the length of the copper lines to your air handler. 

I think the first couple of answers thought you were talking about ice on the suction line and on the evap coil. That is way more common and what I usually see. When you said liquid line it changes the whole situation.


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