School me on Central A/C compressor units

[mtnjam]

We have a pretty old Carrier Day & Night AC compressor unit that sits on the eastside of the house. Stays pretty much in the shade on the hottest part of the day. Pretty sure it's what was installed when the home was built in 1989. Just recently had all the ductwork sealed and the air return enlarged. All in all the size of the home is 1333 sq ft.
It's a split unit so the condensor coils sit in the garage with the rest of the furnace unit. Blower motor is fine, but don't know how much air is exchanged over any given amount of time.
I'm just looking for any good recommendations on replacement compressor units or upgrades to my current system.
Thanks.

[marmot mb]

I would guess you have about a 1.5 to two tonne compressor / condenser. I had a older two tonne unit from the 90's. My power bill would spike terribly when I used the air conditioning. My Brother the AC guru sold me a YORK 3 tonne with a high Seer rating. In all I think it was about 1 tonne too big, but.... he said it's better that way as it will evaporate the heat quicker, causing less compressor and fan time in all saving electrical costs.

It is FAR FAR qiueter, uses far less electricity and certainly cools the house faster and holds it during the fast rising temps of the daytime.

My Brother sold and serviced all types of units and he swears by YORK equipment. Stay away from Lennox as once you buy a Lennox you are stuck using Lennox dealers and Lennox parts.

[capulin overdrive]

if your juice isn't too bad, and it's cooling the house. Why replace?

[bigdude2468]

if your juice isn't too bad, and it's cooling the house. Why replace?

Be careful about putting in a larger unit. The most efficient units are the ones that are sized right. Too large of a unit will cycle on and off and more importantly a unit too large will not remove sufficient humidity; when it is off no humidity is being removed. Have no idea where you live so humidity may not be a factor. Also, you have to be sure that your furnace is large enough to handle the additional A/C capacity if you go larger. Your A/C is only as good as the fan that is circulating the cold air. If the CFM's are not sufficient it makes no difference how big of an A/C unit you install. One thing you can do to check your units performance is to get a small insertion type thermometer. You can get them at a hardware store, they look kind of like a meat thermometer but the dial is much smaller, a little larger than a quarter and the range is like 50 degrees F to maybe 130 - 140 degrees. Measure the temp at the furnace where the air filter is, you want to know what the air temp is before it goes across the evap coil. Then measure the temp after it leaves the furnace or even better, drill a small hole in the ductwork right above where the coil is and insert the thermometer. You should see a temperature drop of about 15 degrees. In other words if the warm air entering the furnace is 90 the cold air exiting should be about 75, 15 degrees colder. Anything above 12 degrees is probably ok but less than that and you have an issue.

This is not a perfect test, other things like a dirty coil, too small a fan etc can have an effect but it gives a general idea. Assuming your furnace is the same vintage as the A/C if you are serious about replacing the A/C you should probably replace the furnace also.