AC going out, 2nd on The Best Memorial Day Timing Ever...

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Old 05-30-10, 02:43 PM
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Red face AC going out, 2nd on The Best Memorial Day Timing Ever...

First I have been living in this house for 4 years and have a good idea of previous years cooling ability. I have been able to cool it to 70 (due to houseguest request) in the past years no problem even during the summer heat, 103-105 for a week or two at a time.

Now that it is getting hot here (high 90’s) but not near as hot as it will in a month I started using my AC. The trouble is that it ran for 14 hours straight yesterday and could not cool the house below 74 degrees. The high yesterday was only 98 and it drops below 80 easily before midnight when I went and set the thermostat to 75 so it would shut off.

When I check the closest vent to the inside unit, about 4 feet away, the temperature is about 10 degrees below ambient. 67 at the vent outlet, 77 in the room where the thermostat is.

Shouldn’t this be about 20 degrees different?

I have a clean filter, about 2 weeks old in use.

As far as the two copper lines going to the evap unit: the small line is barley warm and the big insulated line is not very cold at all. I can feel it at the inlet to the housing where the evap is.

Does this mean anything?

Here is what was done about 3 weeks ago: The Freon was really low so the tech recharged the system and replaced a valve on or near the compressor. Back then I remember that the temperature at the vent was about 51-52 degrees. IT was a cool day, below 80 back then. He did say that he used his leak tester to diagnose the leaky valve. He also used it inside in several locations and it did not go off.

Previously to this in October the blower fan (in the house unit) was replaced since it would work and then stop and work again even when in FAN only mode. At this same time they recharged the AC since it was low.

The system is about 12-15 years old. It is an Amana.

What is the next step? As far as I know the indoor evap has never been cleaned. Is this part of the problem or is there still a leak somewhere?

Thanks for all your help!
 
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Old 05-30-10, 03:09 PM
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You only have a 10 degree "split" at best, since at floor level, cold air return temp is probably even a little less than 77, be my guess. You probably still have a leak. If say the inside coils were dust laden, your coils would freeze and also freeze the big copper line right next to the plenum there. And if evaporator coils were dust laden and frozen you would also notice a lot less air blowing out of the registers, since all the air has to blow thru the coils. If air volume is not a noticeble issue, I bet you still have a freon leak, unfortunately. Although - your coils can still freeze even when you have a freon loss, also.
 
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Old 05-30-10, 05:53 PM
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You should not just recharge the system without finding and fixing the leak. call that guy back again, ask him to find the leak . Small leak is not easy to find, leak detector may not work all the time..
 
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Old 05-30-10, 08:31 PM
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Looks like you have a leak. If the unit is already not cooling properly in three weeks its a pretty big leak and shouldn't be too hard to find by a pro.
 
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Old 05-30-10, 08:41 PM
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Thanks!

So far 3 for leak, either new or not properly fixed before.

In doing more research, the model is an Amana RCC48A2B, and thanks to the innerwebs, this is a 4 ton unit for my 1675 Sq FT condo. It is listed as 12 SEER.

Is 12 SEER really low these days?

I am not sure of the manufacturing date but I can find specs on this model dating from 1995.

If this is really around that old (12-16 years) and there are higher SEER ratings is it time to think about replacement?

Thanks again for the replies!
 
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Old 05-31-10, 11:04 AM
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The leak can be anywhere. may be evaporator, condensor, or anywhere along the line, so, replace (what? everything ?) may not be a good way to fix this.
 
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Old 06-01-10, 02:58 PM
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Here is today's update:

Tech comes out and checks the interior lines as I mention that I don't think that the evap coils have ever been cleaned. He had a very cool snake camera that he tried to get up to see the coils but the furnace heat exchangers were in the way. He then removed the access panel to the evap and then loosened another panel on the evap itself just enough to get the camera in. The coils looked pretty good actually only the very top had some evidence of dust/clog. However the coils were showing some ice on the bottom.

Out at the compressor he verified that it was 2-3 lbs low and did a leak check. No leak outside.

Back inside at the evap coils the fancy refrigerant detector went crazy and he adjusted the sensitivity way down and went over each coil end and bend very carefully as well as the feed pipes/capillaries and as best he could the rear of the evap coils. The leak detector was also bendable.

There were clearly 3 or 4 places on the coil ends that were leaking pretty badly so the evap needs to be replaced. The estimate for this was $1800ish.

After the recent last repair, $900, it is time to get an estimate for replacement. This will happen later today.

He did put in 2lbs and that should last while we decide for replacing the whole thing or just doing the evap. I expect that decision to be made in the next couple of days. I will report back then.

Thanks for everyone's comments!
 
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Old 06-07-10, 02:49 PM
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OK, here is what was installed this morning, all Lennox equipment:

Merit 13ACX-048 Outdoor unit
G40UH-48B Gas Furnace
C33-43B-2F Evap coils
About $5700 installed.

Took about 6 hours, so far much quieter and....much cooler.
 
 

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