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TIP: This Multi-Part Article Describes How To Lower Cooling Costs (and many ways also lower heating costs).  The earliest articles provide the Highest Cooling Savings & Benefits (such as HVAC equipment lasting longer & a more comfortable home).

This is Part 1-C And Part 1-D of our 4-part article about Central A/C Maintenance.

Click Here To Go To Part 1-A & 1-B: AlsPlumbing.com Lower Cooling Costs-Part-1A Furnace Filter.

Al’s Plumbing, in Plano, Texas Provides Full-Service Plumbing; Maintenance, Repairs, and Replacements For Every Plumbing Component In Your Home. We sell and install gas and electric water heaters.  Al’s is near your home in; Northeastern Dallas, Texas; Richardson, TX; & Garland, TX.  We service all homes in southern Collin County, TX, and northeastern Dallas County, TX with no additional travel charges.

Call Al’s Today To Discuss Any Concerns Or Problems You Have With Your Home’s Plumbing. 

We will arrange an appointment at your convenience.

These Are Parts 1-C & 1-D — Of Our 4-Part Article About Routine & Recurring Maintenance Required For Central A/C Systems.

• Part 1-A: Furnace Filters.
• Part 1-B: Outdoor A/C Unit Coil Cleaning.
• Part 1-C: Indoor Cooling Coil.  This coil is inside the furnace or ductwork.  A panel must be removed to gain access to the Indoor Cooling coil.
• Part 1-D  Spring, Annual A/C Tune-Up.

Central A/C Recurring & Routine Maintenance That’s Required

Part 1-C. Indoor Cooling Coil — Check & Clean As Needed

The DOE States: A Dirty Indoor Cooling Coil Reduces Efficiency By Up To -35%.

TIP: The Indoor Cooling Coil Is Typically Inside The Furnace (sometimes it’s in the Ductwork).  It Can’t Be Seen Without Removing A Panel.

Image Source: Shutterstock

Shown: In the photo above — the indoor cooling coil (evaporator coil) is on the right side of the furnace (behind the yellow device).

A Clogged Or Dirty (and likely molded) Indoor Cooling Coil (called: “evaporator coil”).

Image Source: Shutterstock

Shown: Dirty Indoor Cooling Coil (left).  After Cleaning (right).

• Indoor Airflow (through the indoor cooling coil) is around 375 Cubic Feet Of Air Per Minute (CFM) — for each 12,000 BTUs / 1 Ton of cooling capacity).

• A 36,000 BTU / 3 Ton A/C System Moves Around 1,125 CFM.

• A 2,000 Square Feet Home, with 8-foot ceilings, holds 16,000 Cubic Feet Of Air.

• The HVAC System’s Furnace moves this much air (16,000 CFM) every 14.5 minutes.

• Indoor Air Flow Is Filtered Air.  Above we recommended a 3M Filtrete furnace filter be cleaned/vacuumed each month — and replaced every 3 months.

Source: https://www.americanstandardair.com/resources/glossary/cfm/

“Dirty Evaporator Coils:

• Increased energy use by up to +35%
• Reduced the indoor cooling coil’s fan’s ability to move air (through the coil) — by up to -40%.
• Reduced the supply-air (ar coming from the furnace) airflow by up to -75%.

• AND If The Indoor Cooling Coil Is Covered With Live Mold — mold spores blow throughout the home while the furnace blower runs.
• All mold needs to grow and flourish is food (such as dust) and moisture.  The moisture on the coil — is from the humidity the coil removes from the air.

Source: https://www.goodway.com/hvac-blog/2010/09/coil-cleaning-equipment-dirty-coils-cost-power-and-efficiency/

DIY Cleaning Of A Central A/C Indoor Cooling Coil

This YouTube Video Shows Cleaning An Indoor Cooling-Coil (with 23 years of build-up) With A Spray Self-Rinsing Foam Coil Cleaner

Image Source: YouTube Embedded Video Link

Self-Rinsing Indoor Cooling Coil Cleaner

Image Source: Amazon.com Link

Shown: 2 Small Stiff Bristle Brushes

Click On Image To; View Product, Read Details, or Purchase From Amazon.com

TIPS: For Best Results: If you have a lot of built-up on the coil:

1. TIP: Access to the coil will be limited, so small brushes work better.
2. Use a small brush (we show one just above) to remove all the dirt you can get to. Move the brush in the same direction as the coil’s fins — to prevent bending them.
3. Then, with its soft-brush attachment, vacuum the coil in the same direction as the coil’s fins.
4. Spray the cleaner
5. Use this cleaner when you will run the A/C shortly after spraying it.   The cooling coil must get wet to rinse the cleaner away.

Image Source: Amazon.com

Shown: Indoor Cooling Coil (evaporator coil) Cleaner — No Rinsing Is Required

Click On Image To; View Product, Read Details, or Purchase from Amazon.com

This product is “self-rising” — it’s washed away by the condensation-water that forms on the indoor cooling coil.

TIP: Bent Coils Stop Airflow.  If Coil Fins Are Bent– they need to be straightened.

Image Source: Amazon.com Link

Shown: A/C Coils Straighteners Kit

Click On Image To; View Product, Read Details or Purchase From Amazon.com.

A Dirty Indoor Cooling Coil Can Easily Mold & Create A Health Risk

Indoor-Air May Contain Airborne; Toxic Mold, Dust, Dust-Mites & their waste, Pollen, Bacteria, Viruses), Pet dander, Carbon monoxide, Excess Carbon dioxide (due to poor home ventilation), Radon, Rodent droppings, Cockroaches, & their waste, Lead & Asbestos (in homes built before 1979).

TIP: Furnace filters Don’t Remove The Smallest Airborne Particles — If They Did, They Would Reduce Airflow Too Much.

TIP:  In Additional To the Indoor Cooiling Coil — airborne particles settle inside the ductwork.   Because of high summer humidity in DFW — ductwork often sweats.  The dust & moisture inside ductwork create an ideal environment for mold to grow.   Flexible ductwork’s ridges provide many more opportunities to collect particles than metal ductwork.

The DOE States: A Dirty Indoor Cooling Coil Reduces Efficiency By Up To -35%.

End Of Indoor Cooling Coil Cleaning Section 

Clean Ductwork Improves; Airflow, Indoor Comfort & Indoor-Air Quality.

 DIRTY DUCTWORK IS HOME TO; Dust, Dust Mites & Their Waste & Live Mold-Spores — that become airborne whenever the furnace blower runs.

Energy-Saving TIP: Improved Ductwork Airflow — Reduces How Long The A/C & Furnace Must Run. 

HVAC Ductwork Cleaning

The Ductwork Cleaning Equipment In This Video Is; A Truck-Mounted-Vacuum & Compressed-Air Cleaning System.

This YouTube Video Shows 47 Years Of Dust Build-Up Inside HVAC Ductwork

TIP: You Can See The Ductwork After Cleaning — At Time: 3:10 / 3:54.

Image Source: YouTube Embedded Video Link

Click On White Arrow To View Video.

Most (if not all) Ductwork Cleaners Offer Dryer Vent Cleaning (an extra charge)

In The Video Above, At Time 1:55 / 3:54 — You Can See 47 Years Of Dryer-Vent Lint Build-Up Being Removed.

Have The Dryer Vent Cleaned Too.

Dryer vents are the cause of 3,500 house fires each year.  

• There are nearly 14,000 house fires each year in the U.S.
• 25% are caused by lint build-up in the dryer vent.
• Energy-Saving TIP: Dryer lint build-up reduces airflow from the dryer — and lenghtens how long the dryer must run.

Source: https://www.consumerreports.org/clothes-dryer/how-to-prevent-dryer-fires-a6837216286/

Does Your Central A/C Smell Musty?

Dirty Ductwork Provides An Ideal Environment For Mold Growth During Summer

TIP: The More Humid The Weather In Your Area — The More Likely Mold Will Grow In Dirty Ductwork.

TIP: The Image Below Is Flexible Ductwork.  Flex-Duct Has Thousands Of Ridges That Catch Dust.

TIP: Mold Can’t Grow On Clean (Flexible or Metal) Ductwork — Mold Needs Dust For Food.

This YouTube Video Shows Badly Molded Flexible Ductwork. 

Image Source: YouTube Embedded Video Link

Shown: Ductwork Covered With Mold

You Can See More Of This Molded Ductwork At Time: 0:30 / 2:27

In Humid Summer Climates (like DFW) — Mold Is More Likely To Grow Inside Ductwork (because ductwork often sweats in summer).

• Mold needs food (like dust) and moisture (from ductwork sweating) — for mold to grow & flourish
• Because DFW has such high summer humidity — it’s not uncommon for ductwork to sweat during summer.

What Causes Ductwork To Sweat:

• A central a/c system outputs air that’s -15 to -20 degrees cooler than the home’s indoor air temp.
• If the indoor temp = 70 degrees — the output air of the central a/c is as low as 50 degrees.
• When the Dewpoint is higher than the Ductwork temp — the ductwork may sweat inside.
• We show average DFW Summer DewPoints below.

Dewpoint:

• Dewpoint Is The Temperature At Which Dew Forms On Grass.
• Dewpoint temperature doesn’t change with the temperature.
• The higher the Dewpoint Temperature — the more humidity is in the air.
• Dewpoint is the most accurate measure of humidity (because it doesn’t change with temperature).

DFW Summer DewPoints:  

• April: 55 Degrees
• May:  64
• June: 70
• July:  71
• Aug:  70
• Sept: 65 Degrees

Source: https://www.weather.gov/fwd/dfw_records_normals

A. Click Here To See Badly Molded METAL Ductwork: Badly Molded METAL Ductwork

If Link Doesn’t Work — Copy This Below Into Your Browser:

https://www.google.com/search?q=molded+hvac+ductwork&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjzvdn7lJP-AhVSkWoFHXG4DJMQ0pQJegQIBBAE&biw=960&bih=468&dpr=2#imgrc=jPj4vPnTzIpAHM

B. Click Here To See Badly Molded Flexible Ductwork: Badly Molded Flexible Ductwork

If Link Doesn’t Work — Copy This Below Into Your Browser:

https://www.google.com/search?q=molded+hvac+ductwork&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjzvdn7lJP-AhVSkWoFHXG4DJMQ0pQJegQIBBAE&biw=960&bih=468&dpr=2#imgrc=icLnorJAWl6HfM

Image Source: Shutterstock

If Your Ductwork Is 5+ Years Old — It’s Due For A Cleaning

When You Buy A Used Home — Clean The Ductwork + Cooling Equipment’s Coils (as described earlier)

To Ensure Maximum Central A/C Performance

Ductwork Cleaning Frequency Is Affected By:

• number of occupants
• if there are highly allergic occupants
• presence and number of smokers
• presence and number of shedding pets (both hair & dander)
• off-gassing of Volatile Organic Compounds (VOC’s) — that “new smell” is a VOC off-gassing
• if gas is used for cooking (carbon monoxide)

G. Dirty Return-Air Grille(s) Affect Central A/C Performance

• In many older DFW homes, the return-air (air going to the furnace) for the entire house — flows through only 1 or 2 Central Air-Return(s).
• Many older DFW homes have one “Central Air-Return” that’s located directly below the furnace (if the furnace is within the living space).
• Because this air-return is against the floor. Both the grill covering this duct + the duct behind it get dirty fast and needs to be cleaned more frequently.

TIP: An Easy DIY Way To Clean This Duct At The Floor:

1. Turn the Furnace Blower On.
2. Remove Grille (Covering The Duct).
3. Use A Leaf Blower To Blow Dust Loose.
4. Clean Both Sides Of The Grille & Reinstall.
5. Turn The Furnace Blower Off.
6. Vacuum Or Replace The Furnace Filter After Cleaning The Vent.

The Reason To Turn The Furnace Blower On First:  It Minimizes Dust Blowing Back Into The Home (when using the leaf blower).

TIPS:

• Air (going to the furnace) must pass through Return-Air Grille(s).
• If this grille is dirty — it reduces airflow & lowers indoor air quality.
• If you see dust on the grille — it’s time to clean it.
• If you don’t know when the back side of the grille was last cleaned — remove it and clean both sides.
• The grille will be dirtier on the back side than the front.  It must be removed occasionally to clean both sides.

Click Here To See How Dirty A Return-Air Grille Can Get On The Back Side: Dirt Build-Up On Both Sides Of A Return-Air Grille

If Link Doesn’t Work — Copy This Into Your Browser: https://www.directenergy.com/learning-center/sign-your-ducts-need-cleaning

• The grille can be often be cleaned with the soft-bristle (upholstery) brush that came with a vacuum cleaner.
• If the grille is sticky (likely due to cooking grease or smoking) — it needs to be cleaned with soap and water.

This YouTube Video Demonstrates DIY Cleaning A Central Air-Return Grille + The Ductwork Just Behind It. 

TIP: In The Video (At Time 1:25 / 3:57) You Can Easily See The Entire Ductwork System — Is Tremendously Overdue For A Cleaning.

(This Grille is near the ceiling because this home is located where air conditioning is used most of the year.)

Image Source: YouTube Embedded Video Link

For More Details About Indoor-Air Pollutionats — Click On The Link Below To See A Diagram With Detailed Descriptions.

Potential Indoor-Air Airborne Pollutants

If Link Doesn’t Work — Copy This Into Your Browser: https://yellowbluetech.com/2017/07/24/sources-indoor-air-pollution/

Part 1-D. Annual A/C Tune-Up — WHY It’s Important.

Image Source: Shutterstock

SHOWN: Technician Performing Spring Central A/C Tune-Up

An Annual Spring A/C Tune-Up Typically Includes:

• Measure Refrigerant Level.

• TIP: Refrigerant doesn’t get used up.  If it’s low — there’s a leak somewhere in the refrigerant-line.  Leaks can occur at any time, and for many reasons.

• TIP: Refrigerant evaporates as it leaks — so it’s rare to see any visible signs of a leak.

• Low refrigerant causes the System to run longer & harder — than it would with a proper refrigerant level.
• This increases cooling costs + wears the System out faster.

TIP: Most (if not all) New HVAC Warranties Require Annual Spring A/C Tune-Up & Fall Furnace Tune-Up

TIP: If a system failure is due to lack of maintenance — your manufacturer warranty won’t pay for the repair. 

You must have a documented service history.   

According To Trane (brand) HVAC: “Routine Maintenance Is Required as recommended in the owner’s guide to ensure proper performance of the equipment. Repairs That Are Required, Due To Lack Of Routine Maintenance, Are Not Covered by the Trane Extended Warranty Agreement.   Your independent Trane dealer can provide routine maintenance.”

Source: https://americanmechanicalva.com/2022/03/29/trane-services/

Where Refrigerant Leaks Often Occur.

At A Screwed-On Fitting. 

• Central A/C Outdoor Units vibrate tremendously while running.
• Over time, a fitting can come vibrate loose, and refrigerant leaks out.

At A Failing Refrigerant-Valve:  Here Are 4 Refrigerant-Valves In Every Central A/C System (there may be additional valves).

Service Valve:  Where Refrigerant Level Is Checked & Refrigerant Is Added. 

Expansion Valve: A. Controls the rate of refrigerant entering the Indoor Cooling Coil.  B. Expands the refrigerant — from a liquid into a gas.   C. Maintains the refrigerant pressure difference between the a/c outdoor unit (at high pressure) and the indoor cooling coil (at low pressure).  This pressure difference is created by the compressor (in the outdoor a/c unit).

Image Source: Shutterstock

Shown: In the photo above — the indoor cooling coil is on the right side of the furnace (behind the yellow device).

• This coil removes humidity from the air as it passes through the coil.
• Because this coil is wet during summer — these coils corrode over time.

• Low Refrigerant causes the indoor cooling coil to get too cold.  This causes the water (from removed humidity) to freeze onto the coil (see image just below).
• Water on the coil won’t freeze in a System with the right amount of refrigerant.

This YouTube Video Discusses A Frozen Indoor Cooling Coil (evaporator coil)

Image Source: YouTube Embedded Video Link

Shown: A Freezing Indoor Cooling (evaporator) Coil — Indicates Low Refrigerant Level.

A Spring Tune-Up Typically Also Includes Identifying Parts That Will Fail Soon

• The most common Central A/C Outside Unit breakdown (it completely stops running) — is a failed Start-Capacitor.
• The Start-Capacitor is a rechargeable-battery — that gives the Compressor & Fan an extra boost of electricity to get them running.
• Once the compressor & fan are running — the amount of electricity wired to them keeps them running.

• Capacitors wear out.   When they do, the compressor and fan can’t start as designed — and the A/C stops running.
• The #1 Reason a Start-Capacitor Fails (before it’s worn out) — Is due to a failed electric relay-switch (that has stuck closed).
• Failed A/C Capacitors often bulge at the top & bottom.
• Others blow apart (as shown in the video below).

Image Source: YouTube Embedded Video Link

This Video Shows A Failed (stuck in the “on” position) Electric Relay Switch (At Time: 3:15 / 5:19) — Causing The Start-Capacitor To Fail.

The Failed Relay Switch Is Discussed At Time:  1:42 / 5:19

Start-Capacitor Fails At Time: 4:10 / 5:19.  Oil spews out the top of the capacitor as it fails.

TIP: This is why DIY a/c repairs can become dangerous for someone who’s not trained to repair a/c.

Other Tune-Up Services Provided

• Lubricate Moving Parts — Like A Fan Blade Motor.
• Tighten electrical connections.  Outdoor Units vibrate a lot while running — this can loosen electrical connections.
• Visually inspect electrical connections for corrosion or rust & removing any build-ups (build-ups will eventually cause the A/C to stop working).
• Test electrical components — to ensure they are working properly.

• Measure the outdoor unit’s airflow.
• Visual inspection of the coil in the outside unit AND the indoor cooling coil — to ensure they’re sufficiently clean.
• TIP: Cleaning Coils is almost always an extra charge.

• Flush the condensate line to prevent clogs.  This line is what drains the (removed humidity) water from the furnace.

TIPS:

• During The Hottest Weather — Is When  A/C is running the most.
• This puts peak demand on the HVAC System.
• During peak demand — is when parts (that are near failing) are most likely to fail.

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This was Part 1-C and Part 1-D of our 4-part (Parts A, B, C,& D) article about Central A/C Maintenance.

Al’s Plumbing, in Plano, Texas Provides Full-Service Plumbing; Maintenance, Repairs, and Replacements For Every Plumbing Component In Your Home. We sell and install gas and electric water heaters.  Al’s is near your home in; Northeastern Dallas, Texas; Richardson, TX; & Garland, TX.  We service all homes in southern Collin County, TX, and northeastern Dallas County, TX with no additional travel charges.

Call Al’s Today To Discuss Any Concerns Or Problems You Have With Your Home’s Plumbing. 

We will arrange an appointment at your convenience.