Pause in cooling


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Old 08-19-22, 07:22 AM
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Pause in cooling

When I return home after work, indoor temp is about 85 F. I set temperature to 78 and turn AC on. The unit runs continuously most of the time. But sometimes the unit stops halfway (81 F for instance) and remains off for about 10-15 minutes, and then cooling resumes. Once cooled to preset temperature, the unit cycles and keeps temperature. Is this stepwise cooling normal or an indication of problems? AC was serviced recently, including recharge. I moved into the house 3 years ago. First time to recharge AC. The unit is about 18-19 years old.

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08-19-22, 07:22 PM
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An ac system does not consume refrigerant during operation.
Theoretically it would last forever.
Did they find the leak?
 
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Old 08-19-22, 01:55 PM
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The A/C system should not be pausing. It should be in cool mode until the set temperature is met.

Your problem may be a condensation overflow.
Is the air handler in the attic ?
You need to check for a condensate drain line clog.
There may be a float switch shutting down the compressor on overflow.

 
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Old 08-19-22, 07:22 PM
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An ac system does not consume refrigerant during operation.
Theoretically it would last forever.
Did they find the leak?
 
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Old 08-19-22, 08:16 PM
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Yes the air handler is in the attic. Tech said evaporator section is sealed and cannot be open. I will crawl up the attic and look for the condensate drain line. I will post pictures. Thank you.

No, he left after recharging the system. I think he indicated a slow leak in the evaporator.
 
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Old 08-20-22, 08:31 AM
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I lifted the cap on the drain pipe and saw a steady flow of water drip by drip. Is this supposed to be continuous?

Where the drain pipe is connected to the evaporator, I saw another threaded port covered with a red plastic cap. Is this an extra port? Can I open it? I would like to attach a wet vacuum. The overflow pan underneath the unit was dry.

Is the high side copper tubing supposed to be warm?

Thank you.
EDIT: I opened the red plastic cap and looked inside. It was relatively dry.
 

Last edited by PJmax; 08-21-22 at 12:09 PM. Reason: labeled picture
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Old 08-20-22, 02:05 PM
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The primary drain should have water when the system is cooling.

I see 2 copper pipes in your picture. The small pipe is your liquid line and the 3/4 inch larger copper pipe is your suction line.

When the system is running the liquid line is usually around 9 degrees hotter than outdoor temperature and the suction line is usually around 55 degrees.

These copper pipes connect to the outdoor unit.

If you grab the suction line , when the unit is running, and it is not beer cold then your refrigerant leak is likely worse than your tech thought it was and the leak needs to be addressed.

If the liquid line is almost too hot to hold then you need to rinse the outdoor coil.
 
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Old 08-20-22, 06:10 PM
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Thank you. I will read line temperatures and report back.
 
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Old 08-21-22, 12:21 PM
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I labeled your picture.
Your float switch is protecting the overflow drain pan from overflowing.

There are two drain ports. Primary and secondary. The secondary is slightly higher than the primary drain so as long as the primary drain is clear.... no water will flow out of the secondary port.

It is extremely rare for the drain line itself to clog. The typical clog issue is right at the unit where the primary label is pointing. My recommendation is to install a 3/4" PVC connector with a short stub of 3/4" pipe to a 3/4" elbow to a short stub of 3/4" pipe with a cap in the secondary port.

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Based on the picture below... you would remove the secondary cap...pour in a cup or two of bleach and a gallon of warm water. This solution would clean the sludge that forms at the primary/secondary location. Done every year would keep the drain from clogging. This should only be done with the A/C off to keep from spreading the bleach odor.

 
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Old 08-21-22, 08:37 PM
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Thank you, PJmax. Now I am convinced it is clogged. A 5 ton evaporator in a 90% humidity day should give a continuous flow instead of drip by drip. I will install the bleach pouring setup on the secondary port. But I will first disconnect the primary drain pipe and remove the clog physically. Thank you for the advice.
 
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Old 08-21-22, 08:44 PM
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The float switch is on the secondary drain pan.
The secondary drain pan isn't full of water.
It isn't going to be the drain unless you have a float switch on the primary drain pan.
 
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Old 08-21-22, 09:30 PM
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If you had any type of clog.... you'd have water running out of the unit and into the overflow pan.
Since the overflow pan is dry.... the drain must be clean.

If you had a primary drain clog and pulled out the secondary plug.... you'd have water coming out there.

You would know when the drain is plugged.... the water runs everywhere and is very visible.
 
 

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