Close and Seal the Evaporator Coil Case

This project is continued from AC Evaporator Coil Cleaning with Pump Sprayer and Brush.

Clean the AC Condensate Drain Pan

The last project was getting lengthy so I’ll describe this cleaning task now. There was a film of black dirt or mold on the sides and bottom of the plastic condensate drain pan. I cleaned the pan using paper towels soaked in Windex window cleaner because it’s a fairly mild product. This photo was taken before I cleaned the coils with a brush:

AC Evaporator Coils - Clean Bottom of Drain Pan

AC Evaporator Coils – Clean Bottom of Drain Pan

I worked mostly by touch reaching deep inside the A-Frame evaporator coils. There was a lot of scum on the drain pan bottom on this 12 year old AC system because the chilled water inside the pan causes condensation on the pan surfaces:

AC Condensate Drain Pan Cleaning

AC Condensate Drain Pan Cleaning

Clean only the pan sides and bottom and be careful not to bump the coil fins because they will easily bend.

Close and Seal the Evaporator Coil Case

Now that I’ve thoroughly cleaned both the inside and outside faces of the evaporator coils, the coil front cover plate and the case access panel are reattached with screws.

Re-Install the Evaporator Coil Front Cover Plate

The evaporator coil front cover plate is maneuvered back into place behind the refrigerant lines.

While holding the cover plate in position, I turned the baffle plate screw between my index and middle fingers to get the screw started. This was simpler than using a wrench and avoided dropping the screw. Once the baffle plate screw threads caught, I tightened the screw the rest of the way with the 1/4 combination wrench.

AC Evaporator Coils - Reattach Front Cover Plate to Baffle Plate

AC Evaporator Coils – Reattach Front Cover Plate to Baffle Plate

Next I pressed down on top of the baffle plate to align the screws holes in the front cover plate with the A-frame coils:

AC Evaporator Coils - Front Cover Plate Alignment with Screw Holes

AC Evaporator Coils – Front Cover Plate Alignment with Screw Holes

… and fastened the three lower hex head screws. Recall the center screw in the condensate drain pan is longer than the others. The front cover plate acts as a support for the two halves of the coils and you may need to gently push or lift one side of the coils slightly to align the screw holes. Push on the baffle plate or coil end plates only, do not press on the refrigerant lines or copper coil circuits.

Installation Tip: Do not tighten the lower three screws all the way for easier plate adjustment until you have all 5 cover plate screws started.

AC Evaporator Coils - Reinstall Front Cover Plate

AC Evaporator Coils – Reinstall Front Cover Plate

Install the two cover plate screws in the oval slots behind the suction manifold last. The oval slots (red arrows) are for generous hole alignment tolerance:

AC Evaporator Coil Front Cover Plate Reattachment

AC Evaporator Coil Front Cover Plate Reattachment

Now tighten all 5 screws until snug. Be careful not to over tighten the screws because you can strip the threads in the thin sheet metal or plastic drain pan.

Install the Coil Case Access Panel and Seal with HVAC Tape

The coil case access panel is reinstalled with hex head sheet metal screws and a 1/4 inch socket wrench, then sealed with HVAC metal foil tape to prevent air leaks and condensation:

Seal Evaporator Coil Case with HVAC Metal Foil Tape

Seal Evaporator Coil Case with HVAC Metal Foil Tape

I also sealed the large panel opening around the refrigerant lines. There should’ve been a factory made foam gasket to seal around the lines but that was never installed or lost during a past maintenance:

Evaporator Coil Case Seams Sealed with HVAC Tape

Evaporator Coil Case Seams Sealed with HVAC Tape

Thanks for reading,

Bob Jackson

Copyright © 2016 HandymanHowTo.com   Reproduction strictly prohibited.

11 Responses to Close and Seal the Evaporator Coil Case

  1. Ed Joseph August 26, 2014 at 12:02 am #

    Great tutorial on a/c coil cleaning, although a bit lengthy with redundant pictures and sentences. I’ve have cleaned dozens of coils and always wundered if there was a method that was easier and/or less tedious than what you show; I now believe that there is no easier or better way. Your method is basically the best.
    You appear to use between 4 to 5 gallons of water-mixed cleaning solution. Assuming that 1/2 of it goes into the drain pan, then the other 1/2 goes into the heat chamber only to be caught by towels. That is a lot of solution ( a lot more than I ever used); is all that really needed?
    You do not say how long the total process was; from undoing the case & cover, to finally recovering and clean-up. Can I assume 2.5 to 3 hours ? Anyone relatively new at this or thinking to do it for the 1st time please realize that this is just about how each coil cleaning will be, unless you have the ultimate rusted screw syndrome——then add another 1/2 hour. thankyou to Bob jackson.

    • Bob Jackson August 26, 2014 at 8:58 am #

      Hi Ed,
      Good questions!

      > although a bit lengthy with redundant pictures and sentences.
      > I’ve have cleaned dozens of coils…
      I’ll take the bait; please point out the redundancies. I tend to err on clarity and quality. My target audience are homeowners who are unfamiliar with the task and deciding whether it’s a DIY job or better to hire a professional.

      > You appear to use between 4 to 5 gallons of water-mixed cleaning solution.
      It was 2 gallons as stated in the project:

      “I used a full gallon of cleaning solution mixing 1 part Nu-Calgon Evap-Powr-C to 3 parts water, alternating between spraying both sides of the coils. I mixed another gallon of solution in the sprayer for the next steps to clean the coils with the bench brush.”

      > Assuming that 1/2 of it goes into the drain pan, then the other 1/2 goes into the heat chamber
      > only to be caught by towels. That is a lot of solution ( a lot more than I ever used);
      > is all that really needed?
      Hmm, must be my “redundancy” issue again. What I wrote was:

      “I noticed that even with a heavy thick stream the cleaning solution never shot through the coils, instead it wicked down the other side and into the condensate drain pan. Nice! But if you’re concerned about getting cleaning solution on the furnace heat exchanger or blower fan you can place towels over the heat exchanger. (Thanks to Scott A. for the towel tip!)

      Very little cleaning solution dripped onto the furnace heat exchanger and I didn’t use a towel because it wasn’t necessary. I passed along the towel tip from a HVAC technician who thoroughly critiqued the project.

      > You do not say how long the total process was… Can I assume 2.5 to 3 hours ?
      It took me about 2.5 hours because I was pausing to take lots of photos and fussing with the lighting. I take several photos of each step and use only the best in the final project writeup. If I were to do the job again it would take about an hour. The homeowner should plan for 2 hours – possibly more as you indicated – depending on ease of access and condition of the coils which could require more spraying and brushing cycles.

      > unless you have the ultimate rusted screw syndrome——then add another 1/2 hour
      So true!

      Thanks for your interest and excellent questions!
      Bob

  2. Robert Thomas August 31, 2014 at 7:41 pm #

    I thought the clarity was great! Unbelievable demonstration of how to do it, exactly what I’ve been looking for. My A/C is in the attic. The temperature differential is about 11 degrees at best. The AC will run for 15 to 20 minutes and then stay off for about 4 to 6. This all started when the AC ran continuously. The AC repair man came out and said it was the filter–it wasn’t. About 10 pm that evening, the wife says water is dripping from the ceiling. For some reason the auto shutoff didnt work. The metal housing around the unit was sealed up so tight that the unit got water inside the duct box which did not have a drain pain under it; it began to leak and leaked onto the ceiling and insulation. The drain line was stopped up. My AC guy came back out and we blew it out. It stopped up again two weeks later, and I blew it out. It ran almost continuously that day in 100 degree heat and stopped again. This time is was a capacitor which and AC repair man replaced. Now it runs almost continuously. It will stop, but not for long.

    Although I know the coils may be covered and dirty (and quite frankly, after looking up through the duct from the inside of the house and seeing all of the dust build up in there, there’s no way the coils are not dirty; they haven’t been cleaned in 15 years–the age of the unit), I am puzzled by the fact that once the unit gets the temperature down, it doesn’t stay shut off long–meaning the house is heating back up again quickly, and I am wondering if it could be due to my having to remove some of the insulation even though it’s the blow-in insulation and I spread some more out over the area.

    It just seems to me cooling down is one thing, but when the temperature goes back up so quickly. Either hot air is getting into the house or cold air is going out–whichever way that works.

    Do you have any ideas?

    • Bob Jackson September 1, 2014 at 2:56 pm #

      Hi Robert,
      I believe you do have multiple issues with your central AC system. First – you should find a new HVAC repair company because the tech didn’t bother to properly inspect your system on the 1st visit and identify the clogged condensate drain line:

      > The AC will run for 15 to 20 minutes and then stay off for about 4 to 6.
      > This all started when the AC ran continuously. The AC repair man came out
      > and said it was the filter–it wasn’t. ….
      > The drain line was stopped up. My AC guy came back out and we blew it out.
      What’s happening is the drain line is mostly clogged and draining too slowly. The condensate overflow switch would activate and shutoff the AC. When enough water drained the overflow switch would disengage allowing the system to run for a while until it filled up, repeating the On/Off cycle. See this project about condensate pumps for more info. Also see this discussion about clogged drain lines and the Mighty Pump™ A/C Condensate Drain Line Pump.

      Your overflow switch may be attached to the condensate trap in a configuration similar to the EZ Trap.

      The air handler needs to be opened up to inspect the coils, drain pan and condensate drain trap and lines. Something continues to clog the drain, maybe mold & algae?

      > It ran almost continuously that day in 100 degree heat and stopped again.
      > This time is was a capacitor which and AC repair man replaced. Now it runs
      > almost continuously. It will stop, but not for long.
      Which capacitor did the AC repairman replace? Was it the indoor air handler blower motor or the outdoor condenser coil compressor motor capacitor? What may have happened is the indoor air handler was blowing but the outdoor compressor motor wasn’t running due to a bad start/run capacitor. The outdoor condenser fan may run but if the compressor isn’t working then there won’t be any refrigerant circulation and cooling.

      > The temperature differential is about 11 degrees at best.
      An 11 degree temperature drop across the coils sounds too low, it should be in the 20F range. Clogged evaporator coils will greatly reduce the volume of air flow, cooling efficiency and increase the indoor humidity. In fact, clogged coils could increase the temperature drop across the coils because the coils might be icing up, albeit with limited air flow and overall cooling.

      > I am puzzled by the fact that once the unit gets the temperature down,
      > it doesn’t stay shut off long–meaning the house is heating back up again quickly…
      > It just seems to me cooling down is one thing, but when the temperature goes back up
      > so quickly.
      If the AC working too hard and barely able to hold the thermostat setting then it will always be on the “warm side” in the house and probably higher than normal (40% to 60% range) humidity. When the AC shuts off, the indoor air temperature rises more quickly than normal and higher humidity will make it feel uncomfortable. The AC does more than cool the air, it also cools the objects inside the house. Do the walls and furniture feel nice and cool when you place the palm of your hand flat on them? If not, then the house is not getting cooled. BTW – the humidity in my house with the thermostat set to 77F is 50% RH with an outdoor temperature of 88F and 61% humidity on a sunny day. The AC is running almost continually. I have the AcuRite Indoor Humidity Monitor next to a different indoor/outdoor wireless unit and it’s very accurate:

      > Either hot air is getting into the house or cold air is going out–whichever way that works.
      A home energy audit can pinpoint areas for improvement.

      I’d focus on fixing the AC issues first since this can done quickly. Also have your ductwork inspected for breaks and leaks. After that consider what long term improvements are needed for the house insulation, sealing and attic ventilation:

      #1 – Is the attic sufficiently ventilated? Ridge, soffit, eave vents and maybe powered attic fans are necessary. I had ridge vents installed on my home and added a number of new soffit vents.

      #2 – Adequate attic and wall insulation does wonders for preventing heating and cooling losses. Adding attic insulation normally provides the most benefit.

      #3 – “Sun loading” meaning how much of the house and windows are exposed to direct heating by the sun? Large windows can let in a lot of heat. Closing the white plantation shutters on the west side of my home keeps the rooms cooler by a good 10F. In the winter I leave the shutters open for the free solar heating.

      Let me know what you do.
      Thanks,
      Bob

  3. Robert Thomas September 1, 2014 at 5:29 pm #

    Bob, the A-Coils were terrible, caked on, and probably the top four inches of the A-Coils was clogged. I peeled off all i could, then used a brush to help, then washed from the back side with a pump up sprayer. Then sprayed the foam cleaner on the coals, let it soak for a few minutes, and then rinsed the coils again. They look really great.

    While I was in there, I also removed from my blower a three inch piece of foam insulation that had apparently broken off inside and gotten stuck to my blower wheel.

    The return air flexible duct from my porch was kinked in half almost by laying over a piece of foam sheathing in the attic (used to hold insulation on top of the 10′ ceiling where it drops to 8′). I cut out a round opening so the line is not kinked and also used some ac tape to tape up the leak where the AC people had simply spliced that flexible line into my main return air line.

    it’s 94 degrees outside and thermostat is set on 74; yes, I have lots of west windows but they have sun screens on them and we built a pergola to cover some of the windows. Humidity is 55 to 58 the house at this time and the humidity outside is 41. With these temp differences, the AC is running anywhere from 12 to 15 minutes and staying off from 8 to 10 minutes.

    Now the temp differential is about 14 degrees. The unit is 15 years old, and I don’t believe the diff has ever been more than 14 degrees. I actually have two units (one for each end of the house) and neither has ever been over 14 degrees difference.

    Thanks for all your help. I’m just testing at the 74, well be leaving it on about 75 generally in the daytime.

  4. Justin Bennett May 14, 2015 at 7:16 pm #

    I had a similar problem with my system.
    There was water being sucked into the blower compartment ( i have a single stage downflow).
    I managed to take off the cover plate(2 screws i had to use grabbit extractors).
    The cover plate had rusted so much at the bottom, it was un-useable ,so i got some sheet metal and made another cover plate,and installed it.
    The same problem is still there, i dont think i made the bottom part of the face plate wide enough, didnt have a proper measurement due to the old one rusting away.
    A friend mentioned i could just caulk closed the 2 gaps at the ends.
    Any help would be appreciated :)

  5. Justin Bennett May 17, 2015 at 6:50 am #

    Thanks for the advice,, that’s exactly what i did ,made a new plate..The hardest part was getting 2 of the rusted screws out, i have to resort to using bit extractors.
    Came back from the store yesterday with a tube of ” GE Metal Silicone”, that should work just as good as the product you mentioned?

    • Bob Jackson May 17, 2015 at 8:34 am #

      The GE Silicone II* Aluminum & Metal product specifications are very close to HVAC/R caulk product that I cited earlier.

  6. Mary Ripka July 22, 2016 at 4:40 pm #

    Dear Bob,

    I read and viewed your website on how to clean indoor HVAC coils. I, too, have a HEIL HVAC. When my unit was installed, the coils had to be retrofitted over the furnace because of ceiling and venting restrictions. It is very difficult to remove the panel and get to the front of the coils where all the lines go into the system like you did in your instructions. However, I can get to the back of the A coils by removing a metal panel that was retrofitted covering the coils. There is a cover plate (shaped like an A) like the one you show in your pictures. Can the cover plate be removed in the same manner as you did except from the back and then proceed with cleaning inside the A coils? I hope I’m describing my situation clearly. Basically, does it matter if I can get to the coils in back instead of the front? Does the cover plate come off the same?

Leave a Reply