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AIR CONDITIONING & HEAT PUMP SYSTEMS

AGE of AIR CONDITIONERS & HEAT PUMPS
AIR CONDITIONER TYPES, ENERGY SOURCES
AIR FILTER EFFICIENCY
AIR FILTERS, FIBERGLASS PARTICLES
AIR FLOW MEASUREMENT CFM

BLOWER FAN OPERATION & TESTING
BOOKSTORE - Air Conditioning "How To" Books

CAPACITORS for HARD STARTING MOTORS
CAPILLARY TUBES
CIRCUIT BREAKER SIZE for A/C or HEAT PUMP
CLEANING & Legionella BACTERIA
CONDENSING COIL
COOLING LOAD REDUCTION by ROOF VENTS
CRITICAL DEFECTS on A/C SYSTEMS

DEFINITION of Heating & Cooling Terms
DEW POINT TABLE - CONDENSATION POINT GUIDE
DIAGNOSE & FIX AIR CONDITIONER / HEAT PUMP
DUCTS - Asbestos
DUCT INSULATION, Asbestos Paper
DUCT INSULATION for SOUNDPROOFING
DUCT SYSTEM NOISES
DUST, HVAC CONTAMINATION STUDY

ELECTRIC MOTOR OVERLOAD RESET SWITCH
EVAPORATOR COIL or COOLING COIL
EVAPORATIVE COOLING SYSTEMS

FAN NOISES

GAUGE, REFRIGERATION PRESSURE TEST

HEAT LOSS (or GAIN) in buildings

INSPECTION CHECKLIST - OUTDOOR UNIT
INSPECTION LIMITATIONS, A/C SYSTEMS

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 & DIAGNOSTIC FAQs for A/C
RETROFIT SIZING for A/C or HEAT PUMPS

SYSTEM OPERATION

WATER COOLED AIR CONDITIONERS

More Information

Dirty Air Filters on Heating and Air Conditioning Systems       Causes and effects of clogged heating or air conditioning air filters - what problems are caused by a dirty or clogged air conditioner or furnace filter? Not just weaker airflow. How to clean & inspect a washable air filter used in a window unit, split system air conditioner, or portable air conditioner Questions & answers aboutclogged HVAC duct air filters, causes, effects, cure and prevention - washable air filters References

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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.

Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.

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

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: reduce air flow into the building increase the operating cost of the heating or air conditioning system cause dirt to accumulate on the fan blades, wasting your energy dollars - see DIRTY A/C BLOWERS 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 block the cooling coil itself with dirt, reducing system effectiveness and possibly leading to costly repairs lead to frost build-up on the cooling coil and reduced or totally blocked air flow in the system eventually permit dirt to bypass the filter where it soils and blocks the blower fan itself, leading to more costly repairs. 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. If this happens the flower fan can jam, overheat, and the result is a risk of actual fire in the equipment.

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 Accessibility Also see Missing or Leaky 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 include one or more removable air filters that are designed to be simply rinsed clean using cold water.

At left 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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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

Reply:

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.

I'd start by taking a look at the article linked-to at Related Topics and titled LOST COOLING CAPACITY
LOW VOLTAGE TRANSFORMER TEST

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

• a damper closed in the ductwork somewhere
• individual registers are in the "closed" position
• ductwork has come disconnected or crimped or squashed somewhere
• If even the ONE air vent had just WEAK air flow, then provided that your blower unit is actually running I'd look for:
• a coil that has iced over and blocked air flow
• a very dirty blower squirrel cage fan assembly
• a blower that has a loose fan belt or otherwise is not pushing air
• on an older system a dirty evaporator coil in the blower unit