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AIR CONDITIONING & HEAT PUMP SYSTEMS
A/C - HEAT PUMP CONTROLS & SWITCHES
AIR CONDITIONER COMPONENT PARTS
AIR CONDITIONER TYPES, ENERGY SOURCES
AIR FILTER EFFICIENCY
AIR FILTERS, FIBERGLASS PARTICLES
AIR FLOW MEASUREMENT CFM
APPLIANCE DIAGNOSIS & REPAIR
APPLIANCE EFFICIENCY RATINGS
BLOWER DOORS & AIR INFILTRATION
BLOWER FAN CONTINUOUS OPERATION
BLOWER FAN OPERATION & TESTING
BOOKSTORE - Air Conditioning "How To" Books
CAPACITORS for HARD STARTING MOTORS
CLEANING & Legionella BACTERIA
CHINESE DRYWALL HAZARDS
CONDENSATION or SWEATING PIPES, TANKS
DEFINITION of HEATING & COOLING TERMS
DEW POINT CALCULATION for WALLS
DEW POINT TABLE - CONDENSATION POINT GUIDE
DIAGNOSTIC GUIDES A/C / HEAT PUMP
DIAGNOSE & FIX HEATING PROBLEMS-BOILER
DIAGNOSE & FIX HEATING PROBLEMS-FURNACE
DUCTS - Asbestos
DUCT INSULATION, Asbestos Paper
DUCT INSULATION for SOUNDPROOFING
DUCT SYSTEM & DUCT DEFECTS
DUCT SYSTEM NOISES
DUCTS, Asbestos Transite Pipe
DUST, HVAC CONTAMINATION STUDY
ELECTRIC MOTOR OVERLOAD RESET SWITCH
EVAPORATIVE COOLING SYSTEMS
FAN LIMIT SWITCH
GAS EXPOSURE EFFECTS, TOXIC
GAS DETECTION INSTRUMENTS
HEAT LOSS (or GAIN) in buildings
HEAT LOSS (or GAIN) INDICATORS
HEAT LOSS R U & K VALUE CALCULATION
HEATING SMALL LOADS
INSPECTION CHECKLIST - OUTDOOR UNIT
INSPECTION LIMITATIONS, A/C SYSTEMS
LEED GREEN BUILDING CERTIFICATION
LOST COOLING CAPACITY
LOW VOLTAGE TRANSFORMER TEST
MOTOR OVERLOAD RESET SWITCH
MOLD in AIR HANDLERS & DUCT WORK
OPERATING COST, AIR CONDITIONER
OPERATING DEFECTS, AIR CONDITIONING
REPAIR GUIDES A/C / HEAT PUMP
REPAIR & DIAGNOSTIC FAQs for A/C
THERMOSTATS, HEATING / COOLING
THERMOSTATIC EXPANSION VALVES
WATER COOLED AIR CONDITIONERS
WINDOW / WALL AIR CONDITIONERS
WINDOW / WALL A/C SUPPORTS
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.
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Also see our HVAC air filters home page at AIR FILTERS for HVAC SYSTEMS. This website answers almost any question you might ask about air filters for heating or air conditioning systems.
Dirty Air Filters: are a source of increased operating costs and poor cooling system operation. Dirty air filters can and in fact probably will have these bad effects:
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.
Also see Missing or Leaky Air Filters.
Wall-mounted split system air conditioners as well as window air conditioner units include one or more removable air filters that are designed to be simply rinsed clean using cold water.
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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Frequently Asked Questions (FAQs) about clogged HVAC air filters
Question: What's causing a damp, clogged air filter in my air handler?
Roger Cote said: Just had unit installed 2 weeks air flow was fantastic until Saturday started out great then got very little air flow. Shut unit down and re-started Sunday am and got the same result. Looking to remove filter noticed electric box on Furnace blocked filter, also noticed filter has quite a bit of build up 1/8 inch thick. I am assuming this could be my problem. After running an hour dirt gets damp and blocks air flow what is your take
Roger, it would be unusual for an HVAC air filter to go from free flowing to totally clogged in two weeks without an unusual debris source or water source. You cite damp air filter - I agree that would certainly block air flow (and might collapse the filter for an even more dangerous problem if the filter gets sucked into the blower).
Take a look at the condensate handling system in your blower unit to be sure it's draining and not blowing water or leaking water where it doesn't belong. Take a look at BLOWER LEAKS, RUST & MOLD and WATER & ICE IN DUCT WORK and WET CORRODED DUCT WORK
More obscure: if an HVAC system is oversized for the space to be cooled, it might drop the temperature very nicely but not dehumidify - that'll be a bigger problem to fix. If you suspect that problem see if your blower fan can be run on a lower speed - as a test and stopgap measure. We explain air conditioner oversizing at DEHUMIDIFICATION PROBLEMS.
Your system is new, surely under warranty - let us know what the installer and service tech report.
Question: what happens if I install an air filter that is too small?
(6 days ago) acourtland said: Guys. I placed a filter in the unit in the attic that was the wrong size; it was too small. Now, the compressor outside is not working, and I am not getting any cool air. Can anyone tell me what I need to do, or what did I actually break, and what my next steps should be?
Reply: Acourtland, A too-small air filter at the air handler would not be expected to break the outside compressor/condenser. At least not directly.
But severe airflow restriction in the air handler could slow down airflow across the cooling coil (indoors in the air handler) enough that it might ice-up, blocking some or all airflow indoors.
In turn I could SPECULATE that the effect could be unusual refrigerant pressures developing in the whole system and speculate further that in turn that might activate a pressure safety switch that could shut the system down - though it's not exactly what I've seen in residential HVAC systems.
More often the outdoor compressor/condenser continues to run but no cool air is being delivered indoors.
Shut off the system for an hour, or more, and put in the right filter, then restart (turn everything back on) and let us know what happened.
Question: my new central air conditioner doesn't cool very well - what might be wrong?
(July 10, 2011) larry said: I bought a new central a/c new duct work n all, but it doesn't cool that great n the day time when its really hot. the repair man said its because its so hot outside. I've gone to my friends houses and its always nice. what could b the problem
Reply: Larry there are several possible problems with your new system. First, was it installed properly in all regards and second was it sized properly for the home.
Question: Air is only coming out of one of my air supply registers - what might be wrong?
(July 8, 2011) sara said: i turned on my a/c recently for the first time in quite a while. i had replaced the filter prior to starting it up. it seemed to take forever to cool the house and i went around to each room and found only one of the supply vents had any air coming out of it. what could the problem be?
Reply: Since we don't think a clogged air filter is at fault, if you have good air flow at even ONE supply register then I'd look for
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