Find out how to maintain your central A/C unit. Learn what a professional air conditioning checkup should entail and what homeowners can do themselves to keep their A/C units in good repair.
LESLIE: Well, it’s not that hot yet but in just a few short weeks, you’ll be reaching for your thermostat and cranking up your A/C.
TOM: And that’s why now is the perfect time to check your air-conditioning system, to make sure it’s ready to go before that sweltering heat sets in and you’re on the waiting list for a repairman. Here to give us tips on how to get that job done is This Old House  HVAC expert, Richard Trethewey .
RICHARD: Nice to be here, guys.
TOM: And there is nothing worse than finding out your A/C does not work on the hottest day of the summer.
RICHARD: I know.
TOM: It’s happened to all of us once or twice before. How do we make sure that we’re ready before the sun shows up?
RICHARD: Well, it only breaks down on the hot days.
TOM: That’s right.
LESLIE: Of course.
RICHARD: And because you’re dealing with refrigerant and electricity, you really want to call a professional. And any professional is going to come in, he’s going to start by looking at the proper refrigerant or the freon. There’s a bunch of different freons being used. That’s all licensed and you want to make sure the right level is there; too little or too much will give you a lack of cooling.
You know, you also want to check all of the electrical components. It’s amazing to me how many times it’s nothing but a thermostat that’s got a loose wire in the back side of it and just some of the basics. We always think the worst but sometimes, it’s pretty straightforward.
And then it’s to clean the evaporator coils and the condenser coils. Now, the basic refrigeration cycle requires you to extract heat from inside the house and that means air that’s inside the house has to come up through that air handler.
Now, if you’ve got cat hair, if you’ve got no filters, if you’ve got things that are going to clog that coil, it’s going to affect the performance on the taking out of the heat side and the same thing on the other side, outside. If you have a condenser outside that’s supposed to be dumping heat to outside and that’s obscured by leaves or anything else, then you’ve got to make sure that’s clean. And so there’s always coil cleaners the professionals will use to try and degrease or to sort of cut some of that dirt off the coil.
TOM: I think homeowners tend to think that if it worked fine last summer, it’s going to work fine this summer.
RICHARD: Yeah. That’s right.
TOM: And they don’t understand the fact that the evaporator coil, to your point, takes air throughout the entire heating season, as well.
RICHARD: That’s right.
TOM: So that can get clogged even when you’re not running the A/C.
RICHARD: That’s right. Absolutely. That’s right.
Any motors, we want to oil if they can be oiled. You want to calibrate the thermostat; sometimes, it’s just loose on the wall. And you really want to check your filters; the filters are critical. And when I say that, that’s – the professionals are going to check it right off the bat. But there’s other things that the homeowners can do and that starts by checking those filters regularly.
LESLIE: Now, you mentioned that you really should bring in a pro but is it better to bring in the pro at the end of the cooling season or prior to the cooling season starting up? I mean because you mentioned it’s going to run during the winter, as well, and you could get some issues with the evaporator coil. So when do you get that pro in to do that maintenance?
RICHARD: No matter what I answer, people are only going to call for service when it breaks down. But it should be done before the cooling season.
RICHARD: You’re at the mercy of an overworked refrigeration staff if you wait for that hottest day of the year and it all breaks down, because everybody’s calling at the same time. You really – it’s much more sane and logical to call before the problem.
LESLIE: Now what can you do, as a homeowner, to sort of either ready the system for that pro coming in or what things can you do on your own to keep things in tip-top shape?
RICHARD: Now, another really important thing to do is to change the filters. People don’t realize that the air from the house has to go up through this filter and has to then be heated or cooled and then it comes back into the room. Now, that means air is on a lot. If you’ve got cat hairs or dirt that could clog the filter, it’s going to affect the performance of that unit.
TOM: It’s not going to be nearly as efficient because the temperature has to get past all that. It’s almost an insulating mat on the filter.
RICHARD: That’s right. Some people will pull the filters out and then it becomes even worse because then the air-conditioning coil, which has got all kinds of fins in it, gets fully clogged and you’ve got to have a pro come in and clean it.
TOM: And that becomes the insulating mat.
TOM: Now, what about the filters? There’s so many different varieties out there.
LESLIE: And different price points.
TOM: And different price points, too. You have the basic – I call them the “pebble stoppers.”
RICHARD: That’s right.
TOM: They’re the real thin, fiberglass ones for the big cat hairs.
RICHARD: Yeah. Yeah.
TOM: But where do you think a happy medium is?
RICHARD: Well, at the least case, you should at least have those pebble stoppers, just to keep the cat hairs and the basics off. But we find most people settle on the electrostatic filter and that’s one that has a slight electrical charge into it.
RICHARD: Makes the dirt particles become positively charged and attract to the filter. And that’s something you can pull out and wash in the dishwasher and bring back and it can give you high level of filtration.
TOM: And you probably don’t have to change it nearly as much. Certainly not once a month.
RICHARD: Well, that really depends on the air quality in the house. There are houses that if you look on a sunny day, there’s just dirt and dust particles flying all around and a lot of times, household pets can actually exacerbate it pretty good.
TOM: Let me ask you about that winter cover because in the years I spent as a home inspector, we used to find those all the time. And I learned once that in some cases, the warranties on the compressors can be voided by that because of the condensation that collects under those covers. Do you think it’s a good idea to cover your compressor in the winter?
RICHARD: Well, basic, outside condensers are designed to be out – left out in the elements. So, it’s – some people are very nervous about leaves and things getting in, so they want to be put the covers on. And I’m not sure about the warranty item, Tom, as far as the compressor but – I’m not going to say don’t do it but you’ve got to make sure that you pull them off and you get plenty of air flow in the spring. You want – yeah.
TOM: It’s not going to very long if you try to operate it with that cover on it.
LESLIE: Not if you keep it on there.
RICHARD: That’s right. That’s right. Yeah.
TOM: Richard Trethewey from TV’s This Old House, thank you so much for stopping by The Money Pit. Because of your advice, I think a lot of us are going to be a lot more comfortable this summer.
RICHARD: Hope so.
LESLIE: Now you can watch Richard and the entire This Old House team on This Old House or Ask This Old House on your local PBS station.
TOM: And This Old House and Ask This Old House are brought to you by The Home Depot. The Home Depot, more saving, more doing.