Air Conditioning - another frozen a/c question

...or a few questions really.

*the a/c is not frozen at the moment but would you still give some insight - ** thanks


We have an arcoaire a/c unit located on the roof here in Az.
We've been in this house (1600sqft) for one year and have begun extensive remodeling. Last year our unit froze but it was quite obviously from all the dirt around the coils. We cleaned the coils, blower fan etc and had no problems. During construction the framers removed the return grille and everything so it was sucking major dust and debris.

Because we're in the middle of the remodel we've run 6" flex for the time being knowing that 6" only covers 110 sqft. We are one or two vents short for the coverage needed in the living room area where the return and thermostat are located. The other rooms have adequate coverage. The unit runs a lot during the day but it's hotter than heck here so we thought that was fairly normal. It cools off to 75 (inside) at night and shuts off several times. During the day we set it at 82 but it always seems to be 83 so it runs often.

Our split is usually 57 or 59 at the vents and 78-83 at the return (where the filter goes).
This morning it was 82 at the return and 76 at the vent so I knew something was wrong.
The unit was frozen. The big copper line doesn't have any insulation on it btw, should it? It was frozen. The a coils had thin ice but the unit didn't appear to be very dirty at all. We cleaned it anyway and checked the blower fan, clean no dirt and the fan was working. After thawing the ice and cleaning, the vent is 62.5 and the return is 85.5

Obviously it takes more to cool the room because a lack of enough vents. I'm fixing that today. The ceiling is drywalled but not at all finished so I'm adding a "y" and another vent today. I'm afraid it's putting too much pressure on the unit. Once the major work is done we'll have it done properly with rigid 8".

How would we know if the blower fan is overheating and turning off. This is the fan that blows warm air over the coils to keep them from freezing right? Would it also stop the air from blowing out of the vents? No..that's a different blower?

With the air coming out so cold could it still be a freon leak?
We had a massive storm last night - a neighbor thought it could be moisture blowing into the unit and since it was already working so hard..it froze the moisture (rain)?

Outside temperature is only 94 today - the past week as much as 118. We have about 6-10 inches of insulation in the ceiling in various areas...of course where we've popped through to do work it's moved a little over. Our windows are single pane -old. but not an abnormal amount of windows..north facing only.

Our unit says 80,000 btu. The fins aren't bent. I'm trying to think of anything else.
The return is ceiling mounted. The vents are ceiling mounted in the main living area- wall mounted otherwise.

I would appreciate any feedback. Things seem to be going just fine right now but I would hate to have it all start to fail on the weekend when it's 110.

first of you do not have an 80,000 btuh ac unit, you have an 80,000 btuh HEATING unit... there is no such thing as 80,000 buth cooling... cooling is measure in tons... 1 ton making 12,000 buths so all cooling ton measurments are divisible by 12. Yes your unit can be short of refrigerant and still blowing cool... once your unit freezes up, indoor temperature starts to rise, you turn it off to thaw out unit, indoor temperature rises even more, when unit is not iced over anymore, you turn it back on, with 80 degreee + air going over your indoor cooling coil, your suction pressure rises bringing it out of icing range, once colder air starts to pass over your coil your pressue starts go drop... cauing it to ice up again...
it is a common scenario...

also you mention YOU cleaned your indoor coil? if so how, a very dirt coil, only way to get it clean is to pull it, wash it, solder it back in.. you very well may have dirt packed INBETWEEN your fins, if so it will ice up...

icing can be caused by ALOT of situations...

hopes this help and remember when dealing with air conditioning, temperature and pressure walk hand in hand..

You say the framers removed the filter. Very good chance you have dust/dirt in the coil, especially if you have been working with sheetrock. Fine dust can get trapped inside the fins of the coil and the coil may look clean but be plugged.

Depending on the layout of your system you might be able to try one of the foaming evap coil cleaners. Don't use it if your fan draws across the coil though. Otherwise it may be time to pull it and clean it.

acman-south-
Indoor coil? Did I say that? I have too look back. We have an arcoaire gaspack unit. We don't have a split unit...just the outside unit.
The coil that we cleaned is the coil in the unit on the roof of the house. You don't have to take it off and weld it back on. It's easily accessible once you have the panel removed. The filter that has the fins is easily accessible also. We cleaned those too and used a fin comb to be sure none of the fins were bent.

Our unit was frozen again this morning. This seems to only happen when we get a really bad rain storm. The ac unit runs during the day and often because it's so hot here and then when we get a rain storm late at night, the next day it's frozen.

Any ideas?

The filter that has the fins is easily accessible also. We cleaned those too and used a fin comb to be sure none of the fins were bent.

:confused: I am lost here just what do you have? Is this a Nat. or Lp, gas AC unit????

ED;)

I have an arcoaire Packaged unit. Gas heat/electric a/c

There is no inside coil. It's all on the roof.

GPFM48K080E

The filter (fins) was frozen at the top and at the bottom but not at all in the middle.

http://img224.imageshack.us/my.php?image=frozenux8.jpg

the unit is two years old..

Should I just delete the other post?

GPFM48K080E It looks like you have a 4 ton unit there.
The Picture shows the AC coil. Are the blades on the blower wheel back there clean. If they fill up with dirt they dont move the air it should.

Next on that 4 ton unit. You need about 1600 cfm with a 20" flex 18" metal pipe going to it and comeing out of it . This is to get the air over the coil. So if you have that then next is get a hvac to put gauges on it and check the freon.

[QUOTE]Should I just delete the other post
"Yes " Keep it all in one post


ED;)

I'll do that right away.

Do you think part of the problem could be that we don't have enough vents for the square footage that we have?

They ran 6" flex for the remodeled parts of the house- just temporary until the remodel is done. But the main area where the thermostat is located is 15/20 and only has 2- 6" vents. Seiho turbo nozzles..but still the a/c runs often. Especially when it is 105-110.

Thanks so much for your help!

I'm trying to figure out how to delete that other post.

You say you are 1 or 2 vents short so that is a couple hundred cfm. Unit freezes during rain. My guess is low freon. When it rains it cools down the coil enough for it to freeze.

which woud mean a freon leak right? The air coming out still has a 20 degree split supply vent is 53 - at the register (uptake) it's 77. SO it's a 24 degree split. Would that happen if we were leaking or low on freon?

high 103 outside- low 83 outside 40% humidity

I called our a/c guy and unfortunately for him- he had a heart attack! Scary for a guy at 47. Less importantly- I gotta find new a/c guy.

Thanks so much for answering these questions. I also post on a professional board in my industry and it can be frustrating explaining things to people that are non professionals.
I truly appreciate all that you've offered

If the blower is clean and moving the proper amount of air across the coil and the coil is clean, then you need to check the freon pressures. Without that info we are only guessing.

Freezing comes from the temperature of the refrigerant in the coil dropping below the freezing point. This can occur due to lack of refrigerant, reduced air flow or a restriction in the refrigerant system.

I see units freeze quite often when it rains and the unit is either dirty or low on freon. The rain cools the condensor lowering the temperature of the refrigerant enough to freeze.

I called a new a/c guy out but it will be mid week before we can get him out here. Not a big deal. We have really cold air 53degrees and checked tonight and not a drop of ice.

I have a question-

my unit says 80,000 btu. someone earlier said that you divide it by 12,000 to get the ton. Which would be 6.6666
But then I posted my model number in a previous post and Ed Imeduc said I have a four ton unit.

Why doesn't it just say what it is on the side of the darn unit?

Why is there a difference? How do I know what I really have?

It is standard procedure to list the BTU rating of the furnace. The a/c is usually identified by the model number. I imagine they don't list the btu of the a/c because different coils would give different ratings. I know that doesn't apply to a package unit but that is all I can think of.

..With the a/c guy not coming out until wed. I repeatedly questioned my husband (yes, I'm a girl) about the coil inside the unit and the coil outside the unit. Is it dirty? Are the fins bent? That blower is clean right?
Last summer I got on the roof because he insisted there was nothing up there that resembled a filter. There was but it was frozen in a block of ice.
So this year I didn't get up there. I'm afraid of heights and we don't have the ladder we had last year. Plus, he saw exactly what I saw last year.

Well I could hardly stand it. We put a ladder on a table (safe huh?) and I climbed up there. The blower blades were crusted with about 1/8 of an inch of saltillo tile dust. The fins were dirty on the top side of the coils and bent. when you look at the bottom side of the fins they were crusty dirty.
Gahhhh!

I didn't want to say "my husband said" every time I posted..plus many times I talk to a male dominated industry they treat me like a dumb girl.
...and I'm blonde..so..

If the service guy says that we're okay on freon, I get to strange my husband.
He said so!