Home AC can't reach 70 on 95+ degree days


  #1  
Old 07-28-17, 04:37 PM
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Home AC can't reach 70 on 95+ degree days

I maintain my own AC, e.g. keep outdoor unit/coils clean, evaporator clean, filters, etc.

I usallty keep it around 74 in the summer. Recently we've had several 100+ degree humid days here in MO. On those days it will run 100% of the time and never get 74 (may get to around 76). On more normal summer days (80-90 degrees) it will run most of the time but will hit 74 occassionaly and shutoff for a brief time.

Today its 83 out, I turned the AC to 68 as a test and it would run constantly and never even hit 70.

I will have a service guy out to check it, as it migh be a bit low on refrigerant, etc.

But my question is this, is what Im experiencing typical for the average home AC? For example, not getting to 74 on a 100 degree day or 68 on an 83 day.

Thanks in advance
 
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Old 07-28-17, 04:43 PM
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74 on a 100 day is a bit different than 68 on an 83 day.
Humidity plays an important role too.
 

Last edited by PJmax; 07-29-17 at 10:11 PM. Reason: removed incorrect info
  #3  
Old 07-28-17, 05:16 PM
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I live in the Houston area and keep my AC's set at 80 degrees and the heat at 70. AC's can only do so much.
 
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Old 07-28-17, 07:06 PM
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Evaluating your ac is not so much the inside temp vs the outside but the temperature difference between return and supply. If you are getting a good temperature difference, say 18 to 20 degrees (corrections welcome) with good air flow then the ac unit is doing its job. The rest of the performance deals with the delivery system (the ducts) and the house.

Once you know the ac unit is working well then you can turn your attention to the house and improving the house can help in both summer and winter. Consider an energy audit from someone not trying to sell you a new system. Some states have programs that offer those energy evaluations.

Bud
 
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Old 07-28-17, 08:24 PM
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Samc130, In Houston, you should be able to get down to 70 degree inside while outside is 105. If not, either your AC has problem or, as already mentioned, you have duct or house insulation issues.
 
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Old 07-29-17, 11:16 AM
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Thank you all, you gave me some good ideas on things to check. It makes sense and is good to know there is only about a 20 degree difference in outdoor and indoor temps. So on a 100 degree humid day it sounds fairly normal that you are not going to hit 70 or maybe even 74 indoor temperature right?
Thanks again! I was pricing some R22 and OMG!!!!
 
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Old 07-29-17, 02:04 PM
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NO, NO, You should be able to get down to 70 while outside is 100 or 105 or even 115. If 20 degree difference is the best you can do, how about houses in Phoenix where outside temp can reach 120 in the Summer.
 
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Old 07-29-17, 09:47 PM
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The inside air keeps getting cycled through the ac unit and each time it goes through it gets colder than before. A perfectly insulated home would turn into an ice cube. But our homes get heated from the outside so the resulting temperature is determined as much by your insulation as by your ac.

Bud
 
 

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