Working on Central air... freezing up


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Old 07-12-14, 08:19 PM
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Working on Central air... freezing up

To start with, I'm sorry but I don't know what unit I have.

I have a central air unit that keeps froze up last week so my friend who owns an air conditioning service came out & put Freon in it. It has worked pretty well until this afternoon. It runs & never shuts off. The line that comes from inside the unit outside & runs through the wall & comes inside the house into the heat/air system inside... froze up. that line froze up outside where it comes out of the outside unit & before it gets inside the house.

I washed the unit out really, really well, even taking the top of the outside unit off & washing it both outside in & inside out.
I turned it back on after about 20 minutes & after about 10 or 15 minutes the line was frosted up again.

So, I called my friend & he went through some scenarios with me & concluded that it had to be the coil inside the house. He instructed me to move the heater vet pipe out of the way, remove the face plate & use a wire brush to clean the coil. He made sure to tell me to use a wire brush like a welding wire brush & be sure to brush it from top to bottom OR bottom to top... Do not go side to side.

He said to turn the heat on & let the heat go up though the coils & melt the ice. Then do the above.
So when I removed the face plate, I seen there was still some ice on the copper tubes. I checked the coils face (the radiator looking face) & I didn't see any dirt or fuzz or anything. The face was very clean. I gently ran my fingers over the face & nothing. So, I took the wire brush & began to lightly run up & down the coils a couple of times then I looked to make sure I wasn't bending or damaging the face or the coils. There was no damage. I checked my brush & there was not dirt, fuzz or debris or any kind. The brush was totally clean. (This was a brand new brush by the way). So, I tried a little harder & tried to get a little deeper in the coils face. I made 2 or 3 strokes up & down & still no debris. I checked for damage again. Still good.

I noticed there was a right side coil too but he didn't say anything about that. But, I took a little piece of the right side off & looked .... and felt of... the right side coils. There didn't seem to be any debris or dirt there either.

At this point, I put the face plates back on & I have the heat running again, to melt any remaining ice that may still be in there.

SO, I don't see any problems in there. However, I may not have done a thorough enough cleaning, but I believe I did.

Once its thawed out, I may try running the air conditioner again to see if just thawing it out done the trick but i am pretty sure it just going to freeze up again.
Is it possible that the coils just didn't thaw out Tuesday when it froze up then & he came to put Freon it in & just refroze up today?

Any suggestions? Anything you want me to try at this point ? OR Try something else?

As always, thanks in advance ......
TC
 
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Old 07-12-14, 09:16 PM
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Were you able to see the furnace side of your indoor coil?

It can be difficult to access the dirty side of the indoor coil with vertical applications. It can be very easy to break a feeder tube and cause all your refrigerant to quickly leak out of your system when trying to access the dirty side of the coil.

 
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Old 07-12-14, 09:39 PM
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Houston, Thanks for the repy & input.
I'm sorry but I am limited on my AC terminology.

When I took the front plate off the top part of the inside heat/air unit, there was an "A" frame shaped coil in there. Which was probably, two coils. One on the left & one on the right.
I could actually squeeze my head in far enough to use a flash light & look at the left side (as your facing the unit) & I could see that it appeared to be clean.
Obviously, the right side was in such a tight place, I couldn't get my head in there but I was able to use a flash light & mirror to look in there & it also appeared to be clean. I also got my hand in there & lightly felt around on it & there was no lint or dirt on the face of the right side coil. I also lightly run the wire brush over it as well, still with no debris.

My friend also cautioned me about "NOT" moving around the copper lines coming out of the right side & going into the attic. So, I was very careful not to move those around at all.

About 10 minutes after I re-started the air conditioning, I opened the door to the unit & there was a lot of cold air in there so I re-taped around the face plate like it was before with some black Gorilla tape.
Its been about 45 minutes now since I put the face plate back on & its cooling down in here from 90 down to about 84 now.

However, although the line outside is still not freezing up after about 45 minutes, I am still concerned about why it froze/iced up to begin with. I'm concerned that there s still a problem somewhere that initially caused the problem & is going to resurface.

Any advice on what else I might check, or tips & tricks I might look for &/or try?
 
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Old 07-12-14, 09:45 PM
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The picture you posted is of the "A" frame I was talking about. However, in your picture, what I am referring to as the left side, in your picture is pretty much non-accessible. Your right side is fairly accessible.

The copper tube coming out of your "A" frame coils is just backwards & just a bit different than mine. The coils on mine exit from the right side & I couldn't access that side very well.
 
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Old 07-12-14, 09:59 PM
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...............................................................
 
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Old 07-12-14, 09:59 PM
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The triangular panel in the center of the A-coil would require removal to view the dirty side of the coil in my picture.

You could pull the blower and take a picture through the furnace to view the inlet side of the evaporator coil if you have a furnace with a metal vent pipe.
 
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Old 07-12-14, 10:20 PM
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Ah, ok, maybe that's why I didn't get any dirty stuff. You're saying that the inlet or dirty side is the "inside" of the "A" frame. I was only cleaning the outside. The way I understood my friend, I just cleaned the outside.

Hummm, then that right there maybe the problem. If it freezes back up again, I'll just have to tear it all back out again & clean the inside of the coil.

I really appreciate your input.
 
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Old 07-12-14, 10:30 PM
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Did your friend check for leaks before he added the freon ?
 
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Old 07-12-14, 10:48 PM
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I cant say for sure. But I did ask him tonight if he thought it could be a leak & we discussed the possibility. Its possible he did not.
 
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Old 07-12-14, 11:32 PM
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We just checked the outside line again & after about 2 hrs, it has now started to frost over again. So, it looks like ... back to square one & tear it down again.
 
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Old 07-13-14, 08:33 AM
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Sounds like a leak problem which caused low refrigerant. If you can run a week OK, it is not an issue of dirty/clean coil.
 
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Old 07-13-14, 09:04 AM
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Thanks Clocert.

Well, I was up until about 3 am with this last night. I went back into it & cleaned the under side of the "A" frame coils. The left side was about 90% covered with a wet, black, fuzz kinda stuff (you guys know). The right side was about 50% covered in a dry, dusty fuzz. As per my friends instructions earlier, I took the wire brush & cleaned that stuff of the face (I didnt just dig the wire bristles in the face of the coils). They appeared to be clean.

We let it run for 45 minutes or so & it dropped the indoor temp from 87 to 82 without freezing up again, so we went to bed. We got up this morning at 5 & the outside line was frozen up again. So, still, no air.

I am suspecting, one of two things. Its either low on Freon (which I am leaning more toward) OR, I didn't clean deep down into the face (cooling fins) of the coils.

So now whats your suggestions? Anything else I can check?
 
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Old 07-13-14, 09:11 AM
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If you're getting a "normal" amount of airflow (air out of the ducts) before it freezes over, then it's probably not a matter of getting the evaporator coil clean enough. Since all the air passes through the evaporator coil, if it was restricting the airflow because it was dirty/clogged, you would notice reduced airflow all the time (heating & cooling). If the amount of air coming out of the ducts seems to be about what it's always been, then there is probably a leak and the system is low on refrigerant.
 
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Old 07-13-14, 09:50 AM
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It sounds like the DIY job has already been done.
Either you are low on refrigerant or the system must be pumped down so the coil can be taken outside and cleaned with a water hose.

I have had to go back and remove the coil to properly clean it with your symptoms on more than one occasion. The airflow felt good to me and it took several days to freeze.

It is still more likely that you have a leak.

Call your buddy back.
 
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Old 07-14-14, 10:11 AM
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Well after a weekend of trial & error, Houston is right. The checking & testing is over. I called my buddy back & he said since one side of the coil is wet & one side is dry, the coil is bad. To replace it would require also removing the heating unit because of the small place/closet its in, & the coil is on top of the heating unit way up in the closet/space.
Since the heating unit is probably original (gas) unit from in the 80's, he says trying to take it out & re-install it, bumping & jarring it around, its probably going to fall apart because its old & probably rusted internally etc, etc. Of course there would be no guarantee that it would work when re-installed.
As well, our outside AC unit is 10 years old (installed in 2004) & is an R22(?) type which will no longer be supported after 2014..
So, we are replacing the whole heating/AC (R410?) system. He is saying he is giving us a deal on a complete system, installed for $2900. Its a 2 1/2 ton AC unit. I dont know what the heating unit will be. It'll be compatible with what we have now but I dont know what that is.
The house is about 1500 sq ft brick on a slab with 6 vents. One each in 3 bedrooms, kitchen, dining room & living room. None in the two baths etc.
He says we probably dont need a 3 ton which is what we have now..?? He says a 2 1/2 ton should be all we need.
I should add that we do have a small window unit that we run 24/7 in addition to the central AC, in our bedroom (with door open) to help & keep the Central AC from coming on so much.
Currently (with Entergy in La) our electric bill is less than $200 per month.

So, with all this info, in your opinion, do you agree with him?
& are we really getting a deal at $2900 for a complete heat & a/c system installed. He says normally its a $3800 deal..??

Your opinions please

Edit: Oh, BTW, I cant be sure but I believe he is a Trane dealer, so it should be all Trane equipment. Name brand, not off brand stuff...???
 
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Old 07-14-14, 10:39 AM
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Prices vary depending upon where you live and who installs it, etc. However, $2900 for a complete new furnace and central A/C sounds pretty good to me.
 
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Old 07-17-14, 04:20 PM
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Your friend is probably ripping you off. You have a leak. It could be something simple. Most leaks I see are.
 
 

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