Do it yourself Home AC Maintenance

[Ncc1701]

Hi All!

Rather than calling an HVAC guy I want to see if I can perform annual maintenance on my home AC system myself. I have a pretty standard AC system, it is completely separate from the heating system which is baseboard heat.

So I pretty much got the outdoor condenser unit squared away, I removed the dirt from the fins and lubricated the fan etc. etc. My question is really about the indoor evaporator unit. The evaporator is in my attic (see pictures) and I'm not sure even where to begin servicing this thing. Not only is it sealed tight but I'm scared to go near it because if I apply pressure to the sheetrock underneath, I'm going to go right thru the ceiling!

Is servicing the evaporator even necessary? Any suggestions would be appreciated....thanks!

 

[aaronc879]

Is servicing the evaporator even necessary?

If you have to ask that question then I don't see any reason why you would be doing this yourself. I don't know the answer and that is why I wouldn't be doing it myself.

 

[gauss]

I never did any service/maintenance on my evaporator. System is still running fine 20+ years later.

-gauss

 

[Sojourner]

I've never done any annual/routine maintenance on my AC system other than change the air filters, and I wouldn't attempt to open up the sealed evaporator unless I was pretty darn sure I knew what I was doing.

You might want to search YouTube for some videos on how to maintain or service your particular model of AC. But, failing that, I'd just let it be if it's working OK for now.

 

[gooddog]

Worth remembering - YouTube is your best friend for stuff like this.

 

[statsman]

I've never done any annual/routine maintenance on my AC system other than change the air filters, and I wouldn't attempt to open up the sealed evaporator unless I was pretty darn sure I knew what I was doing.

The construction lead for the 2019 house build in Central Texas looked at me rather oddly when I asked if any routine maintenance was needed on the HVAC system. I mainly asked because I figured the unit was going to get far more use here than it ever would back in the Bay Area of California.

He said not really, other than to change the media filter regularly. They are Aprilaire filters (510 model), fairly large, disposable, and rather expense as far as HVAC filters go (about $60-70 each online). The filter manufacturer says they can last a year. We change them every 6 months in late April and late October.

The construction lead did say to not do what some in the new housing tract were doing. In order to save money, they were taking out the filters, blowing out the debris, and reusing them. Those homes may be looking at earlier maintenance issues down the line.

 

[steelyman]

I’ve been told that the more expensive filters can cause the system to have to work harder. Recommendation was to choose decent less expensive filters and change them frequently.

 

[statsman]

I’ve been told that the more expensive filters can cause the system to have to work harder. Recommendation was to choose decent less expensive filters and change them frequently.

Was told the same thing.

Within the Aprilaire 510 series, there are the 510 (MERV 10) and 513 (MERV 13) replacement filters, and both are rated for a year. We were told the 513 was as easy on the HVAC system as the 510, as long as they were changed regularly (for really powerful HVAC systems here in Central Texas, and with good reason). Despite being rated for a year, changing them every 6 months has kept dust from reaching the air outlets.

Aprilaire also carries a 513 Carbon (MERV 13) and a 516 (MERV 16) replacement filter for the 510 series. These are rated for 6 months, and we were told they could put additional stress on the system. Since neither of us has severe allergy issues to require the extra filtration, we are skipping them. In our case, there really aren't "cheaper" options.

 

[Bamaman]

If a HVAC company was going to do annual maintenance, about all they would do is check the refrigerant pressure of the condenser/compressor outside. Inside, they'd change the filter. That's about it.

If the forced air system had a furnace, they'd look inside it for rust, etc. so they could make a determination on whether you need a new unit--sales call of sorts.

What's strange is that I've never seen a home with a central air conditioning unit with ductwork, etc. that didn't have a furnace or at least heat pump included. i would think it would be far less expensive to heat with forced air than baseboard electric heat.

 

[Surewhitey]

I get either MERV8 or 11 filters and change them every 3 months or so. Also, after the pollen drops, I soap and rinse the coils outside. My guy says it should be done at minimum every year.

Turn off the unit and remove the breaker before...

I remove the fan grate and vacuum the leaves and debris in the unit and then spray the coils with dawn soapy water. Set for a couple of minutes and then spray from the inside out from the top to bottom. You'd be surprised how much junk comes out.

Do not use a pressure washer. It can collapse the coils...

 

[jazz4cash]

UGH!!! We have same setup with condenser in the attic but at least our builder placed the unit on a narrow platform that I can perch onto instead of hanging it from the roof as yours appears to be. I’ll NEVER have another attic installed condenser.

In the attic make sure the condensate tray, drain and the backup drain are open and not clogged. Our main drains goes to the sump pump pit so I try to make sure it runs occasionally. The backup drains from an outlet under an wave. It does have a tiny brush on a tether to clean out the trap and a shutdown switch if it backs up but I don’t trust it. We had an HVAC guy up there once and he screwed up the drain line causing a leak and ceiling damage. I look around for obvious signs that a supply or return line is open. One day I’ll rig up tool to measure pressure drop. Maybe check temps at each supply vent. We have 5 returns which is very expensive to change filters. I use mid priced filters and monitor the hours of operation on the t-stay. They get changed about every 4-5 mos..

I think the main concern is keeling the outside unit clean. I plan to add a coil cleaner spray to my routine. Our primary unit is 20 yr old builder grade unit with a tiny leak but the HO warranty has been pretty good about adding Freon. It developed a nasty piston slap a few years ago and the tech that responded said he’d never seen pressures that high. He sprayed it down with coil cleaner (which was not covered) and it’s been running OK ever since, piston slap and all. A can of coil cleaner spray is $12-15.

 

[socca]

I consider paying an A/C guy to do routine annual maintenance just a cheap form of insurance. I buy an A/C replacement filter from amazon when necessary rather than from the A/C company to save a few bucks. In Florida, A/C isn't optional so I'm not willing to be a cheapskate in this category.

 

[Sunset]

OP - Like others have said, I'd only clean the outside part, and change the filter (wherever that is located) ?

Doesn't the attic get incredibly hot in the summer, just when you need the A/C ? Seems like it's not an efficient idea to put the A/C in the hot attic.

 

[Telly]

For the OP - I open up evap cases once every bunch of years to check a few things: That there is no mold growth, that the evap isn't becoming a rusty mess, and that the fins look reasonably clean (that dirt particularly fibrous matter isn't somehow bypassing my 4" thick filters).

I have furnaces in the attic with evaps that are A-coils that lay on their sides. Usually on those there is a panel that can be carefully removed by taking out sheet metal screws. That offers a side-on view of the "A".

From what I can tell of your first pic, the right side, from where the liquid and suction lines are placed (about half way up) plus what looks like the relative thinness of the evap case near-to-far (again, the pic is dark and not a good view of right side), I'm thinking you have an H-coil evap. An evap coil that was purpose-built for horizontal furnaces and horizontal air handlers. The H-coil evap's case is a band of steel that goes all the way around it, right, top, left, bottom.

As such, there is nothing that will come apart on the H-coil itself to see in when installed. Have to separate either the output end (the end towards the octopus of supply ducts off in the distance), or the input end (the return, which I figure is the big round flex duct in foreground of pic). It's possible that pulling all those sheet metal screws holding the return plenum end and return duct, would allow one to pull back the end of the return plenum (while compressing or bending flex duct back and forth like a snake). That should give room to look inside at the face of the evap H-coil.

I note that in the second pic, that I don't see the back of the evap's metalwork on the left side... looks like the sheet metal side goes on by. So maybe the whole assembly was built as a box, and the evap was slid in from the right and fastened down. With the way the refrigerant lines are run, you won't have slack to unfasten however the evap coil is held in, and slide it out to the right to inspect it. So if I was doing it, I would do a good visual to see how that front end cap is held on as I mentioned above, and pull that out to see straight in to the coil's face.

But you have other things to consider... with no plywood securely and safely fastened down with screws to the joists, you do not have a safe work platform. Also, there is the "maybe let sleeping dogs lie" unless you suspect some problem. I would think you could get somebody in to disassemble it enough to look at the H-coil, but it's not going to be a quick in and out job, maybe a job left for a slower time of year for A/C places.

If an evap coil is pretty dirty, there are aerosol cans of coil cleaner that can be used to spray them down, then spray them off with water. Being careful to keep water spray at such an angle and amount that it washes the dirt down into the evap's drain pan, and out the drain... without overloading the pan with too much water at once and have it overflow, or run all over inside the plenums.

The first pic is so dark and at an oblique angle, that you would really need to verify where the blower motor is, and which end is which, return (input) and supply (output), as I may have it reversed. Either way, to open up one end and see the coil, the blower motor can't be in the way, and you need to be within arm's reach of the evap coil to actually do anything inside.

 

[jazz4cash]

OP - Like others have said, I'd only clean the outside part, and change the filter (wherever that is located) ?

Doesn't the attic get incredibly hot in the summer, just when you need the A/C ? Seems like it's not an efficient idea to put the A/C in the hot attic.

It’s amazing that it actually works but the supply and return lines are fairly well insulated. Those prefab flex supply lines look restrictive to airflow too. Even without the condenser located in the attic many homes use the attic to locate the ducts.

 

[NW-Bound]

One way of testing the insulation of the duct is to check the temperature of the inlet/outlet of the system in the "Fan" mode, meaning with the compressor being off.

I once measured the air temperature at the system dust filter, and then the temperature at the outlet register of a furthest room. The difference was shocking to me at 4F. That's the heat gained by the air as it travels through the system.

If I were to build a new home, ductless mini-split systems would be the way to go.

 

[Ncc1701]

THANK YOU all for the very informative answers! especially Telly and Jazz4cash

 

[Ncc1701]

For the OP - I open up evap cases once every bunch of years to check a few things: That there is no mold growth, that the evap isn't becoming a rusty mess, and that the fins look reasonably clean (that dirt particularly fibrous matter isn't somehow bypassing my 4" thick filters)..........
The first pic is so dark and at an oblique angle, that you would really need to verify where the blower motor is, and which end is which, return (input) and supply (output), as I may have it reversed. Either way, to open up one end and see the coil, the blower motor can't be in the way, and you need to be within arm's reach of the evap coil to actually do anything inside.

What a thorough answer, thanks for educating me!

 

[Ncc1701]

OP - Like others have said, I'd only clean the outside part, and change the filter (wherever that is located) ?

Doesn't the attic get incredibly hot in the summer, just when you need the A/C ? Seems like it's not an efficient idea to put the A/C in the hot attic.

The Condensor is outside but the evaporator is in the attic, I think most installations are this way.

Think I'll take the suggestions here and just leave the evaporator alone.

 

[target2019]

Before exploring beyond the sealed casing, I'd sit up there and listen while the unit kicks in and runs a cycle. Then I'd find out how to lockout the power locally. I'd probably next use a flashlight and look around all sides, especially underneath. You might spot a drainage problem just starting. Are the drainage lines working as intended? Looks like you'd need to go outside to check this.

 

[Sunset]

One way of testing the insulation of the duct is to check the temperature of the inlet/outlet of the system in the "Fan" mode, meaning with the compressor being off.

I once measured the air temperature at the system dust filter, and then the temperature at the outlet register of a furthest room. The difference was shocking to me at 4F. That's the heat gained by the air as it travels through the system.

......

Good to know..

I wonder if on cool days, you could heat your house just by running the fan, as I know my attic gets very warm even on cool days due to the sun hitting the roof.

But for A/C, it seems this is a lousy way to do it.

 

[sengsational]

The "annual checkup" for HVAC is probably only useful for the non mechanically inclined. As mentioned, you get in tune with what it's doing normally, and if anything changes, you address it.

If you have never run it without a filter, no need to look at the evaporator.. it's fine. But just because it's taped shut doesn't put it out of reach. Just buy the right tape and re-seal it if you do dig into it.

I've still got the 1993 HVAC in my house limping along. My key to success is never have an HVAC guy near it, hehehe! I've replaced a dozen capacitors (well, maybe not THAT many) on the condenser unit. I've replaced the controller board in the furnace. But never opened up the evaporator box, nor have I lubricated the blower motor (never sounded any different, so didn't feel the need).

This spring the unit froze up, which I determined because I got a great temperature drop when it first came on, then lost the temp drop after running solidly for some hours. A bit of coolant solved that issue.

Any one of those, even just a capacitor, might have landed me a completely new system if one of the big-boys had been on the scene. One of my buddies had a new system installed and come to find out, all he needed was a $5 capacitor... He told me about why he "called the man": the fan on the condenser was warm and humming, but not spinning. Yeah, the big boys make serious money on installs, so that's what they make sure they do.

 

[Ncc1701]

My key to success is never have an HVAC guy near it, hehehe!

My thoughts exactly!

 

[Happyras]

The "annual checkup" for HVAC is probably only useful for the non mechanically inclined. As mentioned, you get in tune with what it's doing normally, and if anything changes, you address it.

If you have never run it without a filter, no need to look at the evaporator.. it's fine. But just because it's taped shut doesn't put it out of reach. Just buy the right tape and re-seal it if you do dig into it.

I've still got the 1993 HVAC in my house limping along. My key to success is never have an HVAC guy near it, hehehe! I've replaced a dozen capacitors (well, maybe not THAT many) on the condenser unit. I've replaced the controller board in the furnace. But never opened up the evaporator box, nor have I lubricated the blower motor (never sounded any different, so didn't feel the need).

This spring the unit froze up, which I determined because I got a great temperature drop when it first came on, then lost the temp drop after running solidly for some hours. A bit of coolant solved that issue.

Any one of those, even just a capacitor, might have landed me a completely new system if one of the big-boys had been on the scene. One of my buddies had a new system installed and come to find out, all he needed was a $5 capacitor... He told me about why he "called the man": the fan on the condenser was warm and humming, but not spinning. Yeah, the big boys make serious money on installs, so that's what they make sure they do.

+1....I have a stock of various capacitors which come in handy. Some systems were so poorly designed/installed, that they often need some help, but not replacement. Under sized air flow or high static pressure etc are killers and not simply due to fouled filters. Occasionally I need to re-tap the blower for more speed and hopefully more flow.

 

[Time2]

It is worth taking a look at the evaporator condition and as someone said check for mold, but also they will get dirty. There are evaporator sprays to help remove buildup if it is present. If you can't walk from ceiling joist to ceiling joist, then don't go in the attic. You can make a big repair and might even hurt yourself.