AC cannot cool below 78F

[James Kandasamy]

Hi BPers,

We have a house that was built in 1984 in Texas. The tenant claims that the AC cannot cool down below 78 F. The outside temperature was around 100 F when they claim this. The AC is running all the time. The AC man says that its common for this type of house and it only cools down to 78% of outside temperature.  The tenant claims that because the AC cannot cool below 78 F, its a safety issue for the tenant. The tenant age is in their 70s.How do i handle the tenant's complain ?

James and Shanti

[Darrell Shepherd]

The house I grew up in wouldn't cool below 78 when it got really hot, really couldn't go more than 20 degrees below the exterior.  It sucked, but we lived with it for years.  That condenser was just too small for that house when it got that hot.

If your climate gets that hot for any length of time, you probably need a bigger unit.  

You can also check the attic.  If there is poor ventilation, that thing could be a 180 degrees and radiating heat into the house.   Its possible you can get attic ventilators and more insulation and be fine.  Some HVAC guys like to staple the runs to the rafters because it looks neat and tidy, but that means you are running your cold air through the hottest part of the house.  Very possible just dropping the air ducts to the floor, blowing some insulation and putting in a power attic ventilator will get you another 10 degrees.   Depends on the house construction, of course, but those things work.

[Matthew Shaw]

A lot of investors spent a lot of time on goggle becoming “AC Experts”...

If an air conditioning system could only cool to 78% of the outside temperature, there would be a lot of extremely unhappy people living in Arizona and Nevada. That’s common sense.

Get a reputable HVAC contractor in there to solve your problem.

[Anthony Rosa]

From what i understand that is normal with central A/C.   It is typical for the house temperature to be 20 degrees lower than the outside temperature.  The bill/receipt for a new central A/C will usually have a statement regarding the inside temperature will have a 20 degree difference from the outside temperature an that is normal..  78F is fine provided the humidity is minimal.

Keep in mind that high ceilings, sunny skies, humidity, skylights, etc..will also have an effect on inside temperature.

Window A/C's, portable A/C's and split units will deliver much lower temperatures then central A/C. 

[Alan M.]

I'd let them out of their lease but I'd also look into getting one of these. We got one for our primary residence - the air coming out of the vents was 8 degrees cooler. Now the house gets up to 74 on a 100 degree day vs. the 81 it would get to before. Well worth the cost of the water, which is minimal. https://coolnsave.com/

[Bonnie Low]

Since you put in a new unit last year I'd have a different company come out and inspect your ducts and insulation. It's not uncommon for ducts to tear or come loose, in which case your cold air is blowing into your attic. Apply more blown in insulation as well - it's not expensive and is much more cost effective than upgrading your AC again. Because we rely so heavily on A/C in upper northern CA, it's common for companies to offer annual maintenance pretty cheap. For example, we pay $149/year to have twice yearly inspections and maintenance. They clean the coils, which makes the unit run more efficiently, check and repair the ducts if needed and change our filters twice per year. It's a good investment for comfort and maintenance so you get more performance and longevity out of your equipment.

[Marian Smith]

@James Kandasamy insulate your attic. Austin is really hot and all my rentals are 1980's built and we blew about afoot of loose fiberglass insulation in the attics to save wear and tear on the ac units as well as keep the tenants bills lower. you can really tell the difference. We put solar screens on west windows even with low e glass , and insulate west facing garage doors. keep the heat out and your unit works better.

[John Dulaney]

Not sure why the AC guy says that the HVAC equipment only cools to 78% of the outside temperature.  One thing you could do, blow in more insulation in the attic if that's an option.  Cover windows on the west side of the house with solar shades or screens.  A good rule of thumb here in Texas is 1 ton for every 400 square foot, so determine if the unit is sized right.  

[Pat L.]

My daughter in Scottsdale AZ had a simile problem. When temps outside hit 115DegF the upper floor would not cool, in fact the 5yr old dedicated 4 ton system just could not get it below 100DegF. My daughter had an excellent a/c guy confirm that a couple of the upper floor cold air returns were NOT connected to the upper floor furnace & blowers. Home was built around the late '90's so previous owners must have suffered this problem for many years. But my daughters' roommate uses the upper floor for her home office setup so it was unbearable.

The a/c guys installed the missing connection(s) plus another strategically placed cold air return vent, with minimal damage to the walls & now the upper floor is very comfortable.