A/C not working as well as last year

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Our A/C has been having trouble keeping up this year. We only run it when the temperature inside the house gets into the mid 80's, which has happened the last few days.

IIRC, last year on a 90-ish degree day the A/C would run almost, but not quite constantly, but was able to maintain 75 degrees in the house. However yesterday when we turned the A/C, around on the temperature outside was 83 and falling and by 8pm or so it was about 75 degrees, but the temperature inside was still 77 (that's after the A/C was running constantly for 4 hours). Today the temperature outside was about 95 and the A/C hasn't been able to keep up at all - the temperature has gone up 3 degrees inside since we turned it on.

The air blowing out of the vents was 56 degrees when I checked yesterday, while the room temperature was 77; so a split of 21 degrees. Air filter is recently replaced. The same blower is used for heat in the summer and the system has no problem keeping the house warm.

What else should I check?
 
Clean your.....evap coil? Whichever one is in the furnace, pretty easy and I felt a diff that I cannot attribute solely to placebo effect. Maybe do the exterior as well.

Re-tape the ducting near the furnace where you can reach it.

Perhaps tape vents closed to balance different rooms and floors.

I did all three of these, and made sunshades for our skylights. It made the second floor of the house go from tolerable for about 20 mins to decent if you keep the doors open.
 
21 degree split is pretty good, maybe the air is going somewhere it's not supposed to go, ducts may be damaged ?
 
If the exhaust is 55 degrees you are good. It might be the furnace fan is blowing as hard as before or you have a plenum box leak that is blowing cold air in the attic instead of throught the vents. Check all the vents for airflow to see if you have some weak ones indocating it may be weak.

Could also be a plugged or pinched duct.

Also Turn off the oven, large plasma tv, incandescent lights, computer or any other big heat generating items in the house to help out.
 
21 degree split is really good, better than mine.

I’m betting you’ve got some bad duct work, something has happened.

Last year my mom’s house had the A/C running constantly and couldn’t keep up, was hot in the house. I found a flexible duct that was completely broken and separated. After I fixed that the house was much cooler, huge difference. Reason is there’s a balance with the a/c, it’s sucking inside air, cooling it, and blowing it back into the duct work. If not all of that air returns, it’s got to get that missing air from somewhere. It’ll suck it from the vent where there’s hot attic air and make the house warm.
 
Thanks. I'm going to check all of the vents to see how much air is coming out. I'm thinking I'll also try to measure air temp right at the air filter, then I'll know if it's sucking in warm air from somewhere.
 
Originally Posted By: NateDN10
Thanks. I'm going to check all of the vents to see how much air is coming out. I'm thinking I'll also try to measure air temp right at the air filter, then I'll know if it's sucking in warm air from somewhere.
If there's anyway you can get to the attic or where the duct work is, do that.

My mom's vents felt the same before and after I fixed the duct that went to it, because it was sucking in the same amount of air regardless.

Measuring vent temp could also help too. I use a $4 meat thermometer.
 
You never mentioned it's age......
Refrigerant / freon may be low. If so...... Get it recharged. My entire home AC (Comfort Maker) lasted about 20 years before needing that R34 freon stuff, which turned out to be expensive to refill. Been another four years now and still cold and running strong.
 
I'm not sure on the age... The house is 25 years old and the A/C is probably original. It uses R22 if that helps date it. How would I tell if it needs to be recharged?
 
Originally Posted By: NateDN10
I'm not sure on the age... The house is 25 years old and the A/C is probably original. It uses R22 if that helps date it. How would I tell if it needs to be recharged?
A/C guy would need to hook up his gauges, but a 21 degree split makes it sound like refrigerant isn't an issue to me.
 
Al Gore, why is their A/C not working as well as last year?

Hmmm, it may need some freon. The compressor might be shot. Someone said evaporator coils...could be. Wait a minute, I know what it is......GLOBAL WARMING!!! AHHHHH!

This has been Environmentalist Theater.
 
On a unit that old, you not only need to clean the evaporator coil but also the squirrel cage blower. Run a finger down one of the air foils and note how much dirt you remove. Once those curved blades get too much dirt in the concave side, they'll greatly lose their ability to move air, which means the blower will stall. Cleaning it means removing it, spraying the foils with degreaser, then rinsing. You may have to scrub each one if it's really bad.

Also, don't use a high-restriction air filter as it may have too much pressure drop. Some old systems do poorly with them and CFM suffers.
 
Yep refrigerant may be low and depending on age a leak etc. Ave life is 10-15 years. Problem with repairing older units is that you are still stuck with a 6 SEER unit with the new ones being a min of 14 SEER. Sounds like you have never had it serviced and if original, well it may be time to replace if 25 years. Way over the expected life of a unit.
 
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Originally Posted By: danez_yoda
If the exhaust is 55 degrees you are good. It might be the furnace fan is blowing as hard as before or you have a plenum box leak that is blowing cold air in the attic instead of throught the vents. Check all the vents for airflow to see if you have some weak ones indocating it may be weak.

Could also be a plugged or pinched duct.

Also Turn off the oven, large plasma tv, incandescent lights, computer or any other big heat generating items in the house to help out.


Good time to change olut incandescent lamps to LED's . One of the Dollar Tree have them for , wait for it , $ 1 .

https://www.dollartree.com/Sunbeam-Warm-White-9-Watt-Medium-Base-LED-Light-Bulbs/p410343/index.pro

I agree , clean coils & check for damaged / leaky duct work .

You may need a shot of refrigerant into the system .
 
Check the Capacitor which sometimes still have capacitance but not the specified capacitance.
So it is not bulging yet.

Capacitance meter is cheap on ebay or amazon, like $15 (not a multimeter).
 
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