Frost inside air handler unit


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Old 03-18-17, 12:08 PM
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Frost inside air handler unit

My AC does not appear to be cooling very good. The temperature at the return measures 82 degrees while the temperature at the coolest vent measures 73 degrees. It took over an hour to drop the temperature 1 degree after dark last night. As this is a condo, the condensing unit is on the roof. I went up and looked at it and it is a RUUD brand unit from late 2003 which appears to be operating as normal and seems to be in very good condition. The interior portion of the system is one of those ceiling units accessed through a hinged metal panel in the ceiling that seem to be in most condos in AZ.

The issue seems to be at the interior unit. there is a connector and 3 separate pipes that go into the coil unit. While I cannot see or access the coil unit itself, these three pipes going to it are very frosty. This appears to be the only issue. The rest of the white specs visible in the picture on the other pipes appear to be paint overspray. I assume this is not normal correct? Is this a simple fix or is there likely an issue with the entire coil unit?

I attached some pictures of the frosty pipes. There is a tag on them that says 63, but not sure what this means.

Thanks for the help

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Old 03-18-17, 12:51 PM
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Your right that's not normal. You either have a restriction in the distributor or its low on refrigerant. Did you see any frost on the condenser ?

BTW 63 is the size of the piston, which is inside the brass part on the distributor.
 

Last edited by skaggsje; 03-18-17 at 12:58 PM. Reason: added
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Old 03-18-17, 12:58 PM
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No, the condenser looks fine. No frost on it or the pipes going to/from it.
 
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Old 03-18-17, 01:01 PM
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One thing to check is to make sure the filter is clean. A dirty filter can be causing the frost.
 
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Old 03-18-17, 01:03 PM
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The first step is to check and/or replace the air filter.
 
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Old 03-18-17, 01:18 PM
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The filter is clean. That's actually the first thing I checked because I wanted to avoid going through that hot attic to get to the flat portion of the roof where the condensers are.
 
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Old 03-18-17, 01:26 PM
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If the airflow coming out of the registers feels normal..... then that would leave you with a low refrigerant issue.
 
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Old 03-21-17, 08:34 PM
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Thank you for the help everybody. I had a tech look at the unit today and he said it was low on freon. What worries me is these are closed systems so I don't think there should be a way for the freon to get low.

Freon was added and it appears to be working fine now. The tech only looked at the condensing unit and did not open the panel to look at the air handler. If you open the panel in the ceiling for the air handler you can see a bluish residue at the left rear. The pipe above this is a refrigerant line. There is what looks like a corroded section on this pipe right near where it goes through the drywall.

He said the freon was just low enough to cause the frost issue that I was having. When he was here I should have told him I wanted him to look at this residue, but I didn't. Does this look like a freon leak to you? If there is freon leaking out how long would it take for the frost to come back? The work is warranted for parts and labor for 30 days so I would hope it would happen during that time if there is going to be an issue.

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Old 03-21-17, 09:24 PM
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Welcome back.

You can't see a refrigerant leak. Sometimes if it's near the condensor you'll see an oily residue. It doesn't leave anything behind so that "stuff" that's in your pictures is not refrigerant.

Your system has a leak. Is it a new leak..... that's hard to answer.

How old is the system ?
Is this the first time it's needed a refill ?
 
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Old 03-21-17, 09:36 PM
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Thanks for the reply PJmax

The system is about 13 years old and is original to the building. As far as I know it has been refilled with refrigerant at least once before. This is AZ so it runs year around and this used to be an apartment complex before it was converted to condos so the AC unit has lived a hard life. At some point a hard start kit was also added to the system, but I don't know if it was really necessary.
 
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Old 03-21-17, 09:46 PM
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So realistically it requires a recharge every 6-7 years. That wouldn't be much of a leak and pretty hard to locate.

It is possible that the leak is getting worse requiring investigation. Keep an eye on it. If it has a problem requiring a recharge soon then they will need to diagnose the leak.

If you can see the coil make sure it's not corroded. Make sure the condensate pan is draining properly so the coil isn't sitting in water.
 
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Old 04-18-17, 07:53 PM
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I took a look at the air handler again since i'm getting close to 30 days from when the service was done and I noticed the upper pipe going into the coil has a little bit of frost on it. Should there be any frost or condensation on the pipes going from the piston to the coil?

Also, I noticed at the bottom of the large pipe visible in the pictures there seems to be an oily substance. I brushed some of it off and it is clear and feels exactly like oil.

I haven't held a thermometer up to the vents again yet, but just wanted to see if any of the above items should be cause for concern.
 
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