AC pipe freezing / pressure is good

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AC pipe freezing / pressure is good

Postby mitch08 » Thu May 24, 2012 10:26 pm

Hey guys... I have a major problem I was hoping someone could help out with.
I have a pretty old r22 central air unit with the compressor outside and the evaporator inside the attic.
It has always been a work horse. No problems. A few years ago it developed a small leak. Refrigerant lasts a few years.

This year it was low so I had my AC tech put it in.
Everything was running great for about 3 weeks. I am in NY so it isnt very hot out yet. mid 70s during the day and significantly cooler at night.
A few weeks after the R22 was added, the unit started freezing up. I didnt realize this and it froze solid and caused a small leak in the ceiling under the attic.

I had a buddy of mine with all equipment test the pressure and everything looked great. I cleaned out the compressor which was unbelievably dirty and it ran great for another 3 days or so and started freezing again. This time I caught it earlier and just turned off the unit.

I called the professional AC tech back and he came and looked at the pressure, condenser and evaporator coil.

He told me the pressure looks fine and it is not being caused by lack of refrigerant.

He said it could be happening because the weather is so much cooler at night. He had me lock the thermostat at 75 degrees and said if it holds it there for a few days without freezing, it is most likely fine and its the outside air temp causing the problme. If it freezes up it is the coil and since they dont make R22 coils anymore, I will need an entire new unit for $5,000 - $6,000. So now Im freaking out. I do not have the money for this right now.

Does any of this make sense? Wouldnt it be more likely that the coil was dirty and clogged than out right bad? And assuming the coil is bad, cant I just get an R22 coil for this unit either online or from a plumbing supply store? Would I really need an entire new unit and have to switch to 410?

that seems very extreme to me...
Any help would be hugely appreciated!!!!!!! Thanks a million in advance.
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- AC pipe freezing / pressure is good

Postby heatseeker » Fri May 25, 2012 10:01 am

number one - They do make r-22 coils.
number two- outside ambient is not causing coil to freeze. If it was so cold outside why would you need your ac on or set at seventy five deg?
The problem is either pressure related or air flow related. I guarantee the pressures are not "good" as your buddy stated.
Number three- If indeed there is a leak then you need to fix it asap because r-22 is skyrocketing in price.
Number four- Get a new ac tech to fix it right and do not attempt to fix it yourself.
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- AC pipe freezing / pressure is good

Postby Freon » Sat May 26, 2012 11:25 am

I will assume the system has not been opened so there is little likelihood of an obstruction at the evaporator coil orifice. That leaves 2 possibilities that heatseaker has already - Low refrigerant and Poor airflow through the evaporator coil. When you know there's no ice in the evaporator coil (the system hasn't run in a few days) turn on the fan and feel the air flowing into the returns and out the supply registers. Is there a good flow? If not check the filters and ducting for any problems. Lastly consider cleaning the evaporator coil or, buy a new one... the price for either a new coil or cleaning may be comparable.
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- AC pipe freezing / pressure is good

Postby mitch08 » Mon May 28, 2012 8:51 am

Thanks guys.

The air out of the registers seems fine. Also when turned on, there is almost exactly a 20 degree difference between the air going in through the filter and the air coming out of the registers.
Until it freezes up of course... then I get no air flow out of the registers until it melts.

Ive had it running for about 4 days now without problems. The first 2 days I did what my AC guy told me to do which was leave it on 75 to see what happens. It was only about 75 degrees out so the AC was mostly off. The last 2 days have been significantly hotter and the AC was running most of the day. I turned it down to 72 for 2 days and still havent had a problem (knock on wood).

So is it possible that outside air temp really was the issue here? This started happening a few weeks after he added refrigerant. Is it possible he added too much? Ive heard of that causing problems.

Thanks again!!!!
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