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I'm really Hot - new fan, condenser fan motor & shroud - Little less Hot

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fisher1

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Discussion starter · #1 ·
Ongoing issue with my AC - original AC, brick house built in 70s, Phoenix, AZ.

AC was not able to keep up with outside temperatures.

Vendor #1 diagnosis 'compressor weak when isolated w/o fan. 21 degree split'. Can someone explain?


Vendor #2 diagnosis (Second Opinion) System checked fine per manufactures specs. Vendor did find condenser fan motor bearings are warn/blade high-on shroud. Warranty authorized fan to be replaced, blade and new shroud. Part were ordered. Vendor said condenser fan motor’s job is too cool compressor so it does not arch and become weak and burn-out. Replaced condenser fan motor, blade and shroud.
System tested without failure per manufacturer specs. With 20 degree split. split went from 21 to 20. What does that mean?

AC still not able to keep up so what would you recommend?
 
#2 ·
The purpose of the condenser fan, is to cool the refrigerant in the condenser coil. So that is returns to a liquid state. The compressor is refrigerant cooled.

What were the outside temps when it wasn't keeping up, and what indoor temp are you trying to maintain.
 
Discussion starter · #3 ·
Received conflicting info from techs on date of AC - house built in 70 and AC is either original or replaced in mid-1980.

1st Tech visit - External AM High 80s/PM 110+ (even hit 117 a few days)
Internal AM Low 90s/PM Mid 90 with AC running continuously (never shut off)

After Repairs - External AM Low 80s (a reprieve)/PM Low 100s in pm. AC runs turns on in am and runs nonstop until 11:30pm. The back rooms still reach 85/86 in the evening 4pm-10pm.

Realtor told me brick houses are great (insulated), but I find it is more like a pizza oven. At night when external temperatures start going down the brick continues to heat the house making bedtime miserable. Because the daily external temperatures have dropped, especially morning, it is difficult to say whether this remedied the issue. I am concerned that in April/May when temperatures rise again.
 
#4 ·
Does your house have solid brick walls or brick facing over framed walls with insulation? Brick is a poor insulator. It absorbs heat and holds it long after the outdoor temperature goes down.

Your post seems to indicate you are dealing with a home warranty company. If so, do not expect a satisfactory outcome. They pay less than what a good technician will work for, so they hire the desperate ones.
 
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Discussion starter · #5 ·
Thank you so much for replying. Nice to know there are knowledgeable professionals available.

House is cinderblock with drywall on inside. Insulation in wall - unknown. Attic insulation in couple inches of blown in type and looks original to the house.

8/7 a tech from AC Co. #1 reported the compressor needs to be replaced.
8/10 tech from Home Warranty said nothing wrong.
8/15 a tech from AC Co. #2 reported condenser fan motor bearings worn/blade high on shroud. RESULT: Home Warranty authorized fan to be replaced, blade & shroud. Parts ordered.
9/13 AC Co. #2 finally replaced condenser fan motor, shroud, fan blade. THIS sounds like a band-aid.


With the AC as is, will the house ever get under 85 degrees when we hit 110+? I highly doubt it.
 
#6 ·
If the system cools, then the tech from company #1 was entirely incorrect about the compressor.
Are both the #1 and #2 companies working under the home warranty? If so, I suggest you just cancel the HW because it will give you plenty of grief and no solution.
Look for a small company with a long-standing reputation. That is where you are most likely to find technicians with a passion for doing what is right and being honest about the repairs.
 
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#7 ·
What's the history of the unit? If you lived there 5 years ago how did it cool?

If the serial number of the OD unit is visible and you know the brand there are websites that will tell you when the unit was built.

20-21 degree split is pretty good in my book.

No mention of basic refrigerant pressures at a particular OD temperature
 
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#9 ·
There are many reasons why an A/C system won't cool near its Btu/hr Rating.

Also, a couple inches of attic insulation is totally inadequate; a major reason why it can't keep-up.

The ceiling joist is 7" high & that is only about R-21; you need R-35 in southern regions to R-50 in northern regions depending on your location.

If you live in a hot dry climate, do U have 450-CFM of airflow per ton of cooling?
 
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udarrell
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