How to clean AC evaporator coils with no-rinse spray foam cleaner for routine seasonal maintenance. If you’re not comfortable cleaning the AC evaporator coils yourself at least you’ll what’s needed when calling a Heating, Ventilation and Air Conditioning (HVAC) professional.

Table of Contents

  1. How to Clean AC Evaporator Coils (this project)
    Seasonal exterior coil surface cleaning with a spray-on foam.
  2. How to Clean AC Evaporator Coils – Part 2
  3. Heavy Duty AC Evaporator Coil Cleaning
    Deep cleaning with professional coil cleaner, pump sprayer and brush.
  4. How to Clean Inside of AC Evaporator Coils
    Interior coil cleaning by removing the coil end plate. Best for very dirty coils.
  5. AC Evaporator Coil Cleaning with Pump Sprayer and Brush
    Clean the coils inside and out.
  6. How to Install a Honeywell Ultraviolet Light Treatment System
    Prevent mold and algae with a disinfectant UV germicidal light.
  7. How to Install a Honeywell Ultraviolet Light Treatment System – Part 2
  8. How to Clean and Straighten AC Condenser Coils
    Outdoor compressor unit maintenance.

AC Air Handler Components

The following photo is the central air handler in my attic. It is known as an “upflow” type because air enters from the bottom and exits out the top.

Attic Air Handler Components

Attic Air Handler Components

The unit combines a natural gas furnace and an air conditioning evaporator coil. It has three major sections:

  1. Blower motor – bottom
  2. Gas furnace – center
  3. 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.

The blower motor forces air upward (recall my air handler is an “updraft” or “upflow” type) through the furnace and air conditioner evaporator coils. The Heat and Cool functions of the thermostat ensure that either the furnace or the air conditioner operate, but never both at the same time. The supply air plenum box sits on evaporator coil sheet metal cabinet. Two large flexible ducts are connected the plenum box. The large trunk flex ducts connect to rigid duct board distribution trunk ducts that lay on the attic joists. Several smaller flexible duct branch lines are taken off the rigid trunk duct to supply air to vents throughout the house.

HVAC Air Handler Evaporator Coil Cabinet, Plenum and Flexible Ducts

HVAC Air Handler Evaporator Coil Cabinet, Plenum and Flexible Ducts

Update: The compressor was failing on the 17 year old AC system. I had the entire central air conditioner and furnace replaced with a Bryant Evolution high efficiency system. The new Bryant system is blows so much colder and reduced my electric bill by 20%.

New 3 Ton Bryant Evolution Attic Air Handler

New 3 Ton Bryant Evolution Attic Air Handler

How to Clean AC Evaporator Coils

Before you begin, turn off the air conditioner at the thermostat and shutoff the electricity to the air handler. There should be a toggle switch (it will look like a light switch) by the air handler to turn off the power. If not then shutoff the electricity at the circuit breaker panel.

The evaporator coil access panel must be removed to access the coils. This is a closeup of the evaporator coil access panel, which is fastened with nine 1/4 inch sheet metal screws and sealed along the bottom with metal foil HVAC tape.

Evaporator Coil Cleaning: Evaporator Coil Case and Access Panel

Evaporator Coil Cleaning: Evaporator Coil Case and Access Panel

Remove the access panel screws with a socket wrench and peel away the metal foil tape along the panel edges (if any).

Remove the Evaporator Coil Access Panel

Remove the Evaporator Coil Access Panel

The access panel is removed exposing evaporator coils:

AC Evaporator Coil Cleaning: Access Panel

AC Evaporator Coil Cleaning: Access Panel

My system has an A-Frame style coil with a removable end plate. Your unit may have an N or slab coil which can be more challenging to access for cleaning. The evaporator coils are basically a heat exchanger, cooling the air inside the house and transferring the heat to the outside condenser unit.

A-Frame Evaporator Coil

This article is continued in How to Clean AC Evaporator Coils – Part 2.

Take care,
Bob Jackson

Copyright © 2019 HandymanHowTo.com   Reproduction strictly prohibited.