Clogged or dirty air conditioner or furnace filter troubleshooting:

This article explains the causes and effects of clogged air conditioning or heating air filters.

Air filter clogging may be the result of high indoor debris levels, abnormal condensate handling or indoor moisture, or even more subtle problems that need to be corrected.

A clogged HVAC air filter increases heating and air conditioning operating cost and in some cases can even be quite dangerous. We describe how to recognize a dirt-clogged air filter, and how to recognize replaceable air filters versus washable air filters.

Dirty Air Conditioner Filters Cause Multiple Problems for an Air Conditioning System

Dirty Furnace or Air Conditioner Air Handler Air Filters

Dirty or clogged HVAC air filters are a source of increased operating costs and poor cooling system operation.

Photos above and at page top show a very dirty air filter at a system inspected and repaired by the author.

While a small amount of building dust and debris on a air handler or blower unit air filter actually increases the air filter's efficiency at removing particles from air passing through the system, more dirty air filters can and in fact probably will have these bad effects:

1. reduce air flow into the building
2. increase the operating cost of the heating or air conditioning system
3. cause dirt to accumulate on the fan blades, further reducing air flow even if a new air filter is installed, thus also wasting your energy dollars -
   
   see DIRTY A/C BLOWERS
4. cause excessive dirt build-up inside the duct system, leading to mold or allergen problems in a building and to the need for more costly duct cleaning or replacement
5. block the cooling coil itself with dirt, further reducing system effectiveness and possibly leading to costly repairs
6. lead to frost build-up on the cooling coil and reduced or totally blocked air flow in the system
7. eventually permit dirt to bypass the filter where it soils and blocks the blower fan itself, leading to more costly repairs.
8. and in extreme cases a clogged HVAC air filter can be dangerous: a blocked air filter can be "sucked" out of position and right into the blower assembly.
   
   Watch out: If this happens the flower fan can jam, overheat, and the result is a risk of actual fire in the equipment. See HEAT RECOVERY VENTILATOR FIRE for an example.

The filters on an air conditioning or hot air heating system should be changed monthly when the system is in use. Discuss with your heating/cooling service professional the possible need to clean the blower fan and duct work.

Air Filter Accessibility

An air filter that is installed where it is not readily accessible may in fact be ignored completely by building owners/occupants, and may rarely if ever be serviced.

Be sure to inspect your HVAC system and ductwork thoroughly to be sure that you know where any and all air filters are located.

A forgotten air filter will mean poor heating or cooling in the building and higher energy costs.

See AIR FILTER ACCESSABILITY

Also see MISSING / LEAKY AIR FILTERS

 

Washable HVAC Air Filters: Washing a Split System Air Conditioner Plastic or Nylon Air Filter

Wall-mounted split system air conditioners as well as window air conditioner units like the one we show just above include one or more removable air filters that are designed to be simply rinsed clean using cold water.

Here you can see the author replacing the left-hand air filter of a wall-mounted split system air conditioner after having washed it clean.

You can wash these plastic mesh filters in the kitchen sink using a dish sprayer but I prefer to perform the operation outdoors (shown below). Outside avoids messing up the kitchen and eliminates any risk of drain clogs.

Watch out: We have read of washable air filters that can be sent through your dishwasher.

We do not recommend this step - as you risk clogging the dishwasher or its pump with dust and debris that wash off of the air filter.

Details of how to remove, clean, and replace these washable air filters are found

at SPLIT SYSTEM AIR CONDITIONERS & HEAT PUMPS

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Continue reading at ENERGY SAVINGS by AIR FILTERS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see DIRTY AIR FILTER PROBLEMS-FAQs, diagnostic questions & answers posted originally at this page.

Or see these

Recommended Articles

• AIR FILTERS for HVAC SYSTEMS
  • AIR FILTER EFFICIENCY
  • AIR FILTERS, FIBERGLASS PARTICLES
  • AIR FILTER LOCATION
  • INSULATION BLOCKED COOLING COIL
• AIR FILTER OPTIMUM INDOOR
• AIR FLOW IMPROVEMENT, HVAC
• DIRTY A/C BLOWERS

Suggested citation for this web page

DIRTY AIR FILTER PROBLEMS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to BUILDING INDOOR AIR QUALITY IAQ

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Or see

INDEX to RELATED ARTICLES: ARTICLE INDEX to AIR CLEANERS FILTERS PURIFIERS

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Citations & References

In addition to any citations in the article above, a full list is available on request.

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