In the early 1990′s, I bought a home in south Florida and did the usual routine of hiring a Home Inspection company. Home Inspectors are worth every penny and among the many items they examine, will check the heating and cooling operation of the air conditioning units – air temperatures and general condition of the unit. You should confirm in advance the Inspector will open up air handler to check the condition of the blower fan, evaporator coils, drain pan, etc. The Home Inspector that I hired back then didn’t open up the air handler and I wasn’t knowledgeable enough back then to ask about it.
When buying that home in south Florida, I made the expensive mistake of not hiring an air conditioning technician to open up and inspect the air handler before I purchased that home in south Florida. Rather, I hired an A/C company to check the unit after I closed the deal and was moving into the home. When the A/C technician opened up the air handler he called me over and said the unit had never been serviced and was a mess. The evaporator coils were covered with mold, heavily rusted and leaking refrigerant. I had the A/C company replace the entire air handler that very day to the tune of $1,700.00.
This is the attic air handler in my current home.
Attic Air Handler - Furnace and Air Conditioner Evaporator Unit
Having learned my $$$ lesson, I always hired a Home Inspector and a HVAC technician to inspect a new home and the HVAC system.
Routine Maintenance
Routine inspection and maintenance is very important to catch problems and save on your electric bill. I recommend hiring an HVAC technician to inspect and maintain the system twice a year; Spring and Fall are best before the summer or winter season begins and you really need your system.
The most important thing a home owner should do is regularly change the air filter. I installed touchscreen 7-day programmable digital thermostats by Honeywell that reminds me when it’s time to change the air filter. A clogged air filter will drive up your electric bill as the system struggles to heat or cool your home.
Other things a careful and knowledgeable homeowner can do is clean the evaporator coils and condenser coils. If you’re not comfortable in doing this yourself, at least you’ll know when to call a professional.
What’s that Thing in the Attic?
This is a the air handler in my attic. It is known as an “upflow” type because air enters from the bottom and exits out the top. The unit combines a natural gas furnace and an air conditioning evaporator coil. It has three major sections:
- Blower motor – bottom
- Gas furnace – center
- A/C evaporator coil – top
The entire air handler sits on a secondary drain pan with a cutoff float switch. The purpose of the secondary drain pan is catch water in case the condensate drain line becomes clogged or the main condensate pan rusts through. The secondary pan will catch the water and eventually activate the float switch to shut down the entire unit before it overflows and ruins the ceiling. Too often, the secondary drain pan becomes rusty and fails to hold the water.
Click on the image for a full size view.
Attic Air Handler
Remove the Evaporator Coil Access Panel
Before you begin, turn off the A/C at the thermostat.
This is a closeup of the evaporator coil access panel. It’s held in place by nine 1/4 inch sheet metal screws and sealed along the bottom with metal foil tape.
Evaporator Coil Housing
Remove the access panel screws with a socket wrench and peel away the metal foil tape along the panel edges (if any).
Removing the Access Panel Screws
The access panel is removed exposing the air conditioner evaporator coils. The evaporator coils are basically a heat exchanger, cooling the air inside the house and transferring the heat to the outside condenser unit.
Evaporator Coils and Access Panel
A-Frame Evaporator Coil
My unit has what’s known as an A-frame style evaporator coil. The coil has a two halves joined together like the letter A and sits on a condensate drip pan. The drip pan forms a moat under the coils to catch the water dripping down as warm humid air from the house is chilled as it moves across the cold coils. The bottom of the A-frame is open so the air can flow through.
A-Frame Evaporator Coil
The better evaporator coils have a plastic condensate pan to that won’t rust through. If the condensate pan were to develop a leak – or the condensate drain were to get clogged up, the water will do one of two things:
- Overflow and pool in the safety condensate pan under the whole unit, which will eventually fill up and trip the safety float switch, shutting down the unit. The purpose of the float switch is to prevent the pan from overflowing and causing water damage to the ceiling and rooms below.
- If the unit doesn’t have a safety pan under the unit, you’ll have water damage right away.
On a typical summer day, the evaporator coils can generate gallons of condensate water as it dries and cools the air inside the home.
This article is continued in Part 2.
Take care,
Bob Jackson
July 14th, 2009 at 8:30 pm
Thanks for providing this information to your readers. This would really give them a helping hand to learn more and would give them idea on how to clean their own air conditioners at home.
August 21st, 2009 at 11:03 pm
Hello,
Thanks for this information. Gave me the confidence to inspect mine and clean them. They were absolutely filthy! I never imagined they would be after just 8 years.
THANKS!!!
Ray Winter
January 4th, 2010 at 6:42 pm
if i use the frost king cleaner in the winter, will i need to rinse?
January 4th, 2010 at 7:54 pm
I think your concerned about the A/C being shut off in the winter and therefore no water condensation to further rinse the coils as there would be in the summer when the system is running. The instructions say it’s a “no rinse” product and I didn’t see disclaimers about seasonal/winter use. The foam breaks down nicely and drains away. You might shut off the heat for an hour so the fluid can do its work.
A second application at the start of summer wouldn’t hurt if in doubt.
June 8th, 2010 at 4:38 pm
Many thanks….as a single mom, I winced at having a tech come out and charge me for something that I could do if I knew how.
June 9th, 2010 at 7:09 am
I’m pleased the article helped you. Often times the work is not difficult, the problem is finding the specialized knowledge to do the work.
June 18th, 2010 at 10:55 pm
Ok I am having issues.. I have had numerous problems with my 3 ton intertherm heatpump. Just about 4 years ago I had a defrost board replaced. Then a fan motor outside the unit.. 3 years ago I had a compassador replaced. Last year I had a tech check out my attic unit and he told me my coils and everything were amazinely clean.. Two month later I need a fan wheel changed, looks like a rat wheel. Ok 2010.. I noticed a dimming of my lights and a few days later a tech came out and told me my compressor was gone, and also whomever hooked up my compassador had the wires backwards and thus my compressor went bad..
Ok the tech replaces the compressor, then the tech tells me I have another huge problem, that my reversal valve is bad and also maybe my defrost board.. So I was a freaking week in 90′ weather and a different tech comes out and is walking round and round and is on his phone, comes to me 10 minutes later and tells me my unit is fixed and all it needs was a screw for the defrost board and a little piece of plastic behind it.. He left but my air wasn’t blowing as hard or cold, a little cool, it took almost 3 hrs to cool home down from 110′ to only 78 while on 68′ thermostat.. Now here is another problem, I come home and unit is on 71′ thermo settings it’s says 79′ on reading and it’s not so cool. So, I call the tech and he tells me I need a good coil cleaning, never looked up stairs in the attic and just because my outside unit is a little dirty but I keep it clean.. I then go outside to rinse down unit and I see my compressor copper pipe to another unit that looks like a huge soda can dripping, then that copper pipe to the pipe outside the unit into the wall with insulation wrap and all pipes are frozen.. I tell my son to turn off the unit and the frozen ice disapears instantly. I tell him to turn it on again and the rightside of all copper pipes because to freeze and the whole pipe turns frosty..
what do you think is the issue, the idiot tech tells me I am mistaking and if I get all of my coils clean I will have better cold air.. It’s ludircrous.. Maybe I do need a cleaning, but one tech tells me my defrost board needs replaced because his reading weren’t correct and the connection wasn’t right or the reserval valve is shot..
Why would my outside pipes frost up and no real cold air inside my unit..
Lastly, I have a contract for the great AHS. American Home Shield and the fly by night idiots are amazing.. One company tells me the other screwed something up and this is why you have so many problems and then one tech from the recent company tells me after he replaces my new compressor I have other issues and a new tech from the same company screws the defrost board together and does his reading and leaves, what is a customer to do.. thanks for any help..
June 19th, 2010 at 9:00 am
There’s so many issues going on that you should have an full installation audit of your Intertherm heat pump. Contact an authorized Intertherm distributor to explain your problems and order an audit.
If you’ve been working with the local Intertherm dealers and believe that’s part of the problem, contact the manufacturer – NORDYNE – at:
NORDYNE
Customer Service
8000 Phoenix Parkway
O’Fallon, MO 63368
Phone: (636) 561-7300
e-mail: mfg_sales@nordyne.com
> Lastly, I have a contract for the great AHS. American Home Shield and the fly by
> night idiots are amazing..
AHS should be sending only Intertherm authorized HVAC technicians to service your system. AHS has had their share of complaints and lawsuits.
> Why would my outside pipes frost up and no real cold air inside my unit.
The outside pipes are frosting because refrigerant gas is (too cold) inside the pipe on its way to the compressor. The pipes will be cool, but something sounds wrong if the pipes are freezing, like the evaporator coil inside the house isn’t working right. The evaporator coil is a heat exchanger that flashes the warm liquid refrigerant to a cold gas through an expansion valve. The cold gas circulates through the evaporator coils as the fan blows warm inside air over the coils. The indoor air gets cold and the refrigerant gas warms up. If the gas is below 32F as it returns to the outside compressor, then the cooling process isn’t working as it should and you’re too warm. The problem could be a number of things: bad expansion valve, wrong gas pressures, compressor problem, etc. The exposed pipes should be insulated, too.
Post back and let me know how your situation is resolved.
July 10th, 2010 at 10:37 am
Thanks for a well written DIY article and good pictures to help illustrate what is involved.
August 27th, 2010 at 12:10 pm
Thanks for the great article. After I gained access to clean my coil, I saw that my A-Frame coil does not have a top, so to speak. I’m referring to the flat piece of metal which sits on top of both coils, at least in the pictures I’ve seen. Witout this piece, there is about a 2 inch gap between the coils. This would seem to be an issue to me, as the air-flow can move thru this gap without being filtered thru the coils. Is this an issue I should adress? Thanks.
August 28th, 2010 at 8:04 am
You are correct – a missing A-frame cap will allow air to bypass the coils lowering efficiency. Contact an HVAC company and maybe they can fit a new cap. Makes me wonder what happened to the original cap? Did it come loose and get blown into the plenum or ductwork and is stuck up there blocking the air flow? You should have a look with a flashlight and small mirror.
August 28th, 2010 at 7:55 pm
Thanks for the advice Bob, I’ll definitely check into it further.