This Is Part 3 of a 3 Part Article:

  • Part 1:      Furnace Control Board – Purpose And Functions
  • Part 2:     Furnace Control Board – Power Surge Protection + Surge Protection For The Rest Of The House
  • Part 3:   Furnace Control Board – Other Ways To Help Minimize Early Failure

For Part 1 Of This Article, Click Furnace Control Board – Purpose & Functions (Part 1)

For Part 2 Of This Article, Click Here: Furnace Control Board – Power Surge Protection (Part 2)

Ways To Help Minimize Furnace Control Board Early Failure

Other Factors That Can Damage A Furnace Control Board

furnace blower motor at bottom of furnace

SHOWN: Furnace Control Board On The Right Side Of The Blower Fan. The blower fan is reflecting onto the bottom of the furnace.

Frequency Of HVAC System Cycling

  • The frequency of cycling (starting & stopping) is one of the largest factors in any HVAC System’s lifespan.  Each cycle creates wear on every component involved.  The furnace control board operates during both the heating and cooling cycles.  The more the system is used, the faster it wears out.
  • Example: A furnace’s heat-exchanger expands & contracts with each heating cycle.  This eventually causes the heat-exchanger to crack.  Once cracked, the heat-exchanger or the furnace must be replaced.

photo with words cracked heat exchanger

  • Example: For Central A/C & Heat Pumps, the initial start-up is the hardest time on the outdoor unit’s compressor.  This is due to two things:
  • Lubrication is not as good at first.  Because the component moving the refrigerant moves very fast, it requires a lot of lubrication.
  • Initial Electricity Inrush is much higher, to start the compressor running. A central a/c consumes about 4 times as much electricity when it first starts.  It’s much like pressing a car’s accelerator further down to get it moving, then releasing some of the accelerator once the car reaches the desired speed.

diagram shows components of HVAC system

SHOWN: The A/C Compressor Either Spins, Or Moves A Piston To Move The Refrigerant.

This movement is very fast and requires notable lubrication. 

One definition of ‘end of life’ for any mechanical item is:

  • When it needs a repair exceeding 25% of its replacement cost
  • Has been in operation for at least 2/3 of its expected life.

Some HVAC Systems need replaced years before the same system in another home.   This is primarily due to how much it runs, and how it’s cared for.

These Articles Show How To Reduce HVAC System Cycling Frequency & Operating Times 

By Decreasing The Amount Of Time Your HVAC System Must Run


Monthly & Annual Maintenance 

How You Care For You HVAC System Is One Of The Biggest Factors In How Long It Lasts

And How Much It Costs To Cool And Heat Your Home

  • The simple task of checking the furnace filter monthly, and replacing when needed, will extend the life of every HVAC System component + dramatically reduce cooling & heating costs.
  • Dirty Filters Cause The System To Run Longer & Work Harder Than Necessary.  If the filter looks dirty, it needs replaced.  The longer & harder the system is forced to run = the fewer years it will last + you spend more to cool & heat your home.
  • The U.S. Department of Energy (DOE) states “A clean filter reduces A/C cooling bills by up to 15%!”

dirty and clean furnace air filter  very dirty and buckled furnace air filter

Shown: Dirty Filter compared to new.            This filter was so clogged that it buckled.  This allowed dust & dirt into the furnace, cooling coil, and ductwork. 

Annual AC Outside Unit Cleaning & Inspection Is The Next Most Important Maintenance

  • Annual Inspection & Cleaning (as needed) Of The Outdoor A/C Unit will disclose any failing components, or low refrigerant level.  This provides the opportunity to replace failing components, avoiding a breakdown during peak cooling season.  A refrigerant recharge helps ensure the a/c is cooling at its maximum efficiency.
  • Cleaning the outdoor unit’s c (as required) has a dramatic effect on both its lifespan & electricity consumption.
  • The US Dept. Of Energy states “A clean A/C outdoor unit’s coil can decrease energy consumption by up to 30%!”
  • very dirty and clogged a/c condenser coil
  • Before & After Cleaning Of Outdoor A/C Unit


Top Causes Of Circuit Board Failure

There are numerous reasons for why components fail.  Some failures are slow and graceful  This allows time to identify the failing component and replace it before it quits working.  Other failures are rapid and unexpected.

The most common reasons for Printed Circuit Boards (PCB) such as your furnace control board to fail include:

  • Aging
  • Over or Under Voltage (power surges & sags)
  • Excessive Heat in the PCB’s immediate environment
  • Change in operating environment
  • Contamination
  • Exposure to Dust
  • Exposure to Water or Moisture
  • Corrosion:  Oxidation occurs when oxygen bonds with metal.  Since printed circuit boards are largely made of metal, they often corrode.
  • Chemical fumes: Fumes from certain chemicals are corrosive. If a PCB is in close proximity to these fumes (such as from some cleaning solutions) the fumes can contribute to corrosion. **



HVAC System Life & Corrosive Contaminants In Indoor Air

photo of corroded printed circuit board

SHOWN: Corroded Control Board

Furnace Control Board Failure Can Be Accelerated By Corrosive VOC’s Within Indoor Air

Many products, such as some cleaning solutions, give off fumes known as Volatile Organic Compounds (VOC’s).  If the PCB is operating in close proximity to the fumes, they can contribute to corrosion of the circuit board.  We discuss this below.

The furnace control board is near the blower fan.  It’s subjected to enormous amounts of air each time the furnace cycles.  The furnace will move 1,000 Cubic Feet Of Air Per Minute (CFM) for a 2.5 ton a/c.  That size a/c cools an 1,800 to 2,000 square feet home.  The effects of contaminants within the air can be magnified due to the amount of air passing through the HVAC System.

Knowing corrosive VOC’s can damage a furnace control board, of much more concern is their heath impacts on your body.  We discuss VOC’s in detail below.  We also describe a solution to nearly rid your home of  VOC’s within indoor air.

Click Below For An EPA Article On VOC’s And Their Effects On Your Health: Indoor Air Quality & Volatile Organic Compounds

image says common indoor air problems

Your First Thought Might Be “There Are No Corrosive VOC Producing Products In My Home.”  In Fact, There Are Likely Many!

  • VOC’s are airborne compounds emitted as gases. VOC’s are released from many commonly used household products and building materials
  • Volatile Organic Compounds (VOCs) within indoor air can create a host of health issues.   The most common reactions to indoor air VOC’s are: irritation of eyes, nose, throat, and skin.  Also allergies, asthma, and related respiratory health symptoms can be magnified.
  • VOC’s Off-Gassing Occurs When New Items Release Volatile Organic Compounds (VOCs) And Other Chemicals Into Surrounding Air.
  • Anything That Has A “New Smell” Is Off-Gassing VOC’s.  They Are The Source Of The Odor.
  • Example Of VOC’s Off-Gassing:  Some new vinyl shower curtains have a strong smell when you first hang them.  The smell is VOC’s releasing into the air.  As the shower curtain  ages, it continues to release VOC’s until they are gone.  Once the VOC’s are gone, the shower curtain no longer smells.  TIP:  Keep the door closed and run the bath vent fan until the odor is gone.  This may take several days.


Note: VOC’s Tests Are Available To Determine The Amount of VOC’s In Your Home’s Indoor Air.  Here is a link to one:  ***

*** We do not endorse any specific brand of VOC’s Tests, only because we don’t have first hand knowledge of all products available.

Some Of The Most Common Corrosive VOC Producing Products Are:


  • Drugstore type rubbing-alcohol for home use
  • Solvents
  • Cleaning fluid

STYRENE: It’s Used In:

  • Foam cups
  • Rigid plastic products such as cups, plates, trays, utensils
  • Packing peanuts

BENZENE  It’s used in:

  • Gasoline
  • Furniture wax
  • Detergents
  • Inks
  • Glues
  • Paint, lacquer, & varnish removers
  • Paints and paint thinners

TOULENE  It’s used in:

  • Gasoline
  • Moisturizing Cream
  • Nail Polish
  • Nail Polish Remover
  • Dry Cleaned Clothes
  • Laundry Starch
  • Shoe Polish
  • Thick Line Coloring Pens & Markers
  • Household Cleaners — Both Liquid & Aerosol
  • Floor Polish
  • Furniture Polish
  • Caulk & Sealants
  • Paints and Paint Thinners

SOURCE: [accessed Feb 13 2018].

UV Lights Nearly Eliminate VOC’s + Many Other Indoor-Air Pollutants

image say indoor air quality


There Are 2 Types Of UV Lights For HVAC Systems

For The Indoor Cooling Coil:  A “stick type” light is installed near the A/C Cooling Coil — to kill & prevent mold growth.

The indoor cooling coil (inside the furnace or ductwork and not visible at a glance) is wet all summer, as it’s what removes humidity from the air.  In the diagram below, it’s located in the ductwork just above the furnace.  The proper term for it is “evaporator” coil.

Over time, this coil will collect some dust from air moving through the furnace.  The combination of dust and water is all mold needs to establish and grow.

diagram shows components of HVAC system

diagram showing uv light in hvac ductwork

The cooling coil is below the UV light.  The blue light casts a blue color at the top of the cooling coil

photo a/c coil with uv light


Al’s Sells & Installs The APCO MAG — UV Light For Indoor Cooling Coilphoto of apco brand mag uv light for a/c indoor cooling coil

The APCO MAG Light For A/C Indoor Cooling Coil


 Whole House Air PurificationA UV Light System To Purify Moving Air.

This UV Light System Is Installed Inside HVAC ductwork.  

diagram showing uv light in hvac ductwork


Al’s Sells & Installs The APCO UV Light Whole House Air Purifier

photo of alpco s129 air sanitizer


Here’s How The APCO Whole House Air Purifier Works

Airborne Contaminants Can Be Divided Nearly Roughly Into Thirds”

  • Particulates
  • VOC’s & Odors — VOC’s create many odors.
  • Biological Contaminants — such as Mold & Germs.

Air Filtration removes particulates from the air.  It cannot reduce or eliminate VOC’s.  It can’t reduce odors (though carbon pre-filters may help absorb odors). 

air contaminates percentages diagram


The APCO Whole House UV Light System Purifies Air As It Passes By — With A Process Called PhotoCatalytic Oxidation (PCO)

Photocatalytic Oxidation

PhotoCatalytic Oxidation (PCO) occurs when UV light rays shine upon a Titanium Oxide coated surface.   This process creates highly reactive electrons that aggressively combine with indoor-air contaminants such as; Volatile Organic Compounds, Bacteria, Mold & Fungus.  The PCO process disintegrates these indoor-air contaminants, leaving only harmless water vapor & carbon dioxide.

Odor Control

APCO cleanses the air by transforming odor-causing VOC’s into harmless water vapor & carbon dioxide.

The UV-C light in APCO works just as well at keeping AC coils clean as non-PCO products (when it can be located to do both jobs).  Mold clogs the indoor cooling-coil.  This shorten HVAC System lifspan + wastes energy.  UV-C light kills the mold and prevents new mold growth.


For over a century scientists have known about the germ-killing properties of UV-C light. Because this frequency of light is filtered out by the Earth’s atmosphere, mo microorganisms have defenses against it.  It works by scrambling germs’ DNA, preventing germs from reproducing.



Al’s Plumbing, Heating & A/C in Plano, Texas provides maintenance and repairs for every Central A/C, Furnace, & Heat Pump brand.  Additionally, we sell & install thee brands of new HVAC Systems:

  • American Standard (same company as Trane)
  • Ameristar (same company as American Standard)
  • Coleman HVAC (same company as York HVAC)

Al’s also provides repairs & replacements for every plumbing component in your home.

Call Al’s today to discuss any concerns or problems you are having with your HVAC System or Plumbing.  We can arrange an appointment to meet your schedule.  We also provide 24/ Emergency Service.