Ac not cooling.


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Old 11-20-15, 03:23 PM
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Ac not cooling.

Hello, im new to my home and have an ac that is not cooling proberly. cools about 4 degrees then will not cool anymore and ran for 3 hrs. Ive had it checked and was told the charge is good, paperwork said it had a 18 degree temp difference between the evap coil. House is 1160 sqft and ac is 2 ton. Every thing ive read is thats the proper size. I think it one of two proroblems. 1. Duct size is too small. My ducts are 6x18, 2 tons requires 800cfm and that duct ive read is rated at 520 so its not pushing enough air to my house due to small ducts. 2 my furnace blower is pushing 1400 cfm, could this be too much airflow' its almost twice as much recommend for a 2 ton ac. Could anyone of these be my problem. Filter is new, condenser and evap coil are clean.
 
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Old 11-20-15, 06:23 PM
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Whats up

measure the temperature difference AT the air handler NOT the registers. Ishould be 17-21F depending on where you live. Physically look at the indoor coil surface, see if its frozen. Check the size of the return, check all outlets are open and not blocked. count the branches and then find the registers they go too see if they all have airflow. Unless you have a balometer, you don't know what you have for airflow. undersized ductwork is very noisy.
Check to see if the return duct is picking up heat on its way back to the air handler. Measure entry air temp and compare with the air handler. do same with supply side.
 
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Old 11-20-15, 06:59 PM
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Welcome to the forums.

You're in Michigan ? What is your outside air temperature ? 45 degrees and flurries ?
It might be a little too cold to be checking an A/C system out.
 
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Old 11-21-15, 06:59 AM
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Yeah a little cold now. Was a problem ive been researching for acouple months. Evap coil was not frozen. All registers had airflow, but not as strong as ive had in other houses maybe by a third to a half as fast , thats why i think it might be airflow not refrigerant. Not turning over the house enough. Ill check all the returns to see if i have enough
 
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Old 11-26-15, 05:01 PM
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That temp-drop is dependent on the INDOOR %Relative Humidity level.
Temp-drop at around 50%RH should normally be 18 to 20F.

INDOOR Higher humidity above 50% = less temp-drop.
Lower INDOOR humidity below 50% = higher/more temp-drop.

INDOOR Humidity differences have to be factored-in when using the temp-difference to estimate airflow CFM.
 
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Old 11-29-15, 07:05 AM
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Long run time

Your condenser may have run a long time BUT this doesn't mean the compressor
(heat remover) was. I suspect the compressor wasn't. One way to tell is constantly monitoring the suction line temperature. If it doesn't stay cold, the compressor is cutting out. If it doesn't stay cold, confirm it with an ammeter. This is a start. Of course gauges tell a lot more info on which way to go.
 
 

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