Home Central Air Con Maintenance Questions

lowpolyjoe · July 14, 2015, 02:31:03 PM

Hey Everybody.

I've got a pretty old central air setup in my house. I really don't want to replace it right now, but it doesn't do such a great job at cooling my house.

I did a little reading recently on what I might be able to do myself to improve performance. There weren't too many bent fins on the compressor, but I straightened whatever I could with a butter knife. I then cleaned the fins with compressed air (there was a lot of stuff between them in some spots). I moved a bunch of junk away from the compressor to improve air flow. It could be psychological, but I think those efforts helped slightly. Keeping all the shades down in the house really helps too.

I've got a couple of questions.

Is it common to recharge the refrigerant in a home AC unit? If that would help I would shell out some cash for that.

My compressor is on a south facing slope on the side of my house, sitting in full sun all day :(. There used to be large shrubs giving it some shade, but they were blown down in Hurricane Sandy a while back. How much (if any) would shade help the function of the compressor?

Any other tips to get the most from the AC?

I'd appreciate any advice you might have. We were planning to replace the HVAC system this year but our kitchen is sort of falling apart and we're gonna try to take care of that first. The AC is high up on the list for replacement in the not-too-distant future but I'd really like to put it off at least another year or two.

Thanks,
Joe

Magicman · July 14, 2015, 08:50:24 PM

Shade would help. Maybe you could build a wood fence.

Only add more freon if it is low. Yours probably takes R22. Make sure that your return air filter is clean.

T Red · July 14, 2015, 09:47:08 PM

Quote from: lowpolyjoe on July 14, 2015, 02:31:03 PM

Is it common to recharge the refrigerant in a home AC unit? If that would help I would shell out some cash for that.

My compressor is on a south facing slope on the side of my house, sitting in full sun all day :(. There used to be large shrubs giving it some shade, but they were blown down in Hurricane Sandy a while back. How much (if any) would shade help the function of the compressor?

Not common to recharge, unless you have a small leak. You really would need a gauge set to check the pressures. Plus a tank of R22 is $200-300.

IMO shade would not help as the compressor uses lots of air flow to work.

Tim

lowpolyjoe · July 14, 2015, 09:58:06 PM

Thanks for the feedback guys.

I forgot to mention that I do change the return filter often to keep a clean one in there.

I was thinking I would hire an HVAC company to charge the refrigerant if you guys thought it was a good idea. Sounds like there's no way to know if it's needed without a pressure gauge. Maybe i'll make some call and see how much they charge to come measure the system to see if it's low.

Mooseherder · July 14, 2015, 10:12:12 PM

Sometimes your air handler coils needs cleaning also. The AC mechanic can spray a cleaner on there and rinse off lightly. Can you see them when you change your filter?

yukon cornelius · July 14, 2015, 11:22:09 PM

I used to own a heating and cooling company so I could help. shade does help BUT!!! it has to be far enough away to allow a lot of air exchange. shut off your outside unit and turn off the breaker then wash the coil out. from the inside to the outside is best way but it requires you to remove at the very leas a panel or most commonly the top with the fan to get to it. if you don't feel comfortable with that from the outside in is better than nothing. check your fan motor for free movement. check the side of the motor for 2 small plastic plugs one at each end of the motor. these are oil ports. a 3 in 1 oil works well for it. several motors do not have these so if you cant find them it may just not have them. let it dry out and you are mostly done outside. inside you will need to check and change your air filter. I will tell you that the heppa filters that are only 1 inch thick will severely restrict your airflow and older systems were never designed for them. check your fan motor on the furnace/air handler. it should be removed and cleaned. dust accumulates on the fan and reduces the capacity. oil that motor as well. the indoor coil (evaporator) gets clogged on the side the fan blows into. blow it out or get a cleaner that foams to push the dirt out. make sure your power to it are off first. rinse if necessary but try not to get too much inside the furnace. let it dry and you are ready to try it out. turn it on and go outside. a way to get an idea if your unit has enough refrigerant is to let it run for about 10 minutes. feel the large line near the outside unit(condensing unit) the large line (suction line) should be cold and sweaty. as cold and sweaty as a can of soda just removed from a cooler of ice. if the line gets frosted there is a good chance it is low on refrigerant. other causes are no or little air flow across the indoor coil, clogged coil, too restrictive / clogged filters, clogged ducting improper ducting and so on. that's a good start. if you need any other assistance I will do my best to help you out.

ScottAR · July 15, 2015, 01:58:01 AM

What Yukon said. I would only add that the small line next to the suction line should be a little warmer than the outside air but if it's considerably hotter then you have an airflow issue... Dirty coils, clogged filters etc.

If that is the case and you clean out the restriction the pressures drop and the unit may need charging. The restriction bulids heat and heat builds pressure in the system pushing out refrigerant.

Some of the clues my uncle taught me. Did HVAC work for 30 odd years.

Cleaning the outside unit is pretty straightforward. Turn off the breaker at the panel or pull the disconnect if it has one. Pop out some screws for the lid and they lift off. Coil cleaner comes in two types, indoor or outdoor and it's about $20 a gallon of concentrate. Follow the mix/dilution ratio on the label and mix in a cheapo garden sprayer. Start at the bottom of the coils and work your way up to be sure you get it all. Wait a minute or two for the foaming action to do it's thing then rinse with a garden hose. **DO NOT USE A NOZZLE ON THE HOSE.** Just use the stream of water or you risk bending the fins. They do make fin combs in various spacings to make straightening the fins easier.

I'm not in the trade but being a landlord requires many hats. I have 3 good tradesmen I call on if I get stumped or it's more than I want/can do.

lowpolyjoe · July 15, 2015, 08:14:25 AM

Thanks a ton for all the info everybody

Not much spare time during the week, but this weekend i'll try some of the things suggested.

We're using a Merv 14 filter that's 1" thick. I change it approximately once a month and it's usually fairly dirty by then. We have a lot of critters making a lot of allergens. Maybe I should downgrade to a lower rating to improve airflow?

yukon cornelius · July 15, 2015, 10:06:44 AM

Quote from: lowpolyjoe on July 15, 2015, 08:14:25 AM
Thanks a ton for all the info everybody

Not much spare time during the week, but this weekend i'll try some of the things suggested.

We're using a Merv 14 filter that's 1" thick. I change it approximately once a month and it's usually fairly dirty by then. We have a lot of critters making a lot of allergens. Maybe I should downgrade to a lower rating to improve airflow?

look into adding a thicker filter/ filter box. the thicker the filter generally means more pleats/folds equaling more surface area which equals more air flow.