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Air Conditioner or Heat Pump System Operating Defects & How to Fix Them AirCondAPedia © Enter your search terms Submit search form   Search This Website - InspectAPedia.com

• Air conditioning & heat pump operating defects & what to do
• Air conditioner won't start, noisy, or short cycling
• Air conditioner does not produce enough cool air volume or air is not cool enough
• High air conditioner bills or tripping air conditioner circuit breakers

This chapter discusses Air Conditioner or Heat Pump System Operating Defects & How to Fix Them. This chapter is part of our more extensive air conditioning inspection, diagnosis, & repair document which describes the inspection, diagnosis, and repair of residential air conditioning systems (A/C systems) for home buyers, owners, and home inspectors. Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution. © Copyright 2008 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use the links at page left to navigate this document or to go to Other Website Topics. Green links at left show where you are in our document & website.

OPERATING DEFECTS - Air Conditioning System Maintenance & Operating Defects

Here we list typical, readily observed, air conditioning system operating defects. Use the links at the left side of any of our pages to find more detailed information about these and other air conditioning system defects, as well as diagnostic and repair procedures. If readers return to the first chapter or view the A/C chapter index, the major components of an air conditioning system are described, sketches and photographs are provided, and common defects for each component are listed along with visual or other clues that may suggest a problem or probable failure of A/C components.

• The air conditioning system will not operate at all: power may be off, controls may be improperly set, or the system may be inoperative. (Confirm that the system has electrical power and that all of its control switches and thermostat are set to "on" and "cooling" positions. See CONTROLS & SWITCHES)
• The air conditioning system operates but does not produce cool air, or not enough cool air. See LOST COOLING CAPACITY
• The air conditioning system operates but there is not enough cool air flow at the registers. (See DUCT SYSTEM DEFECTS.)
• The compressor was short-cycling, that is, turning itself on and off rapidly, perhaps every few seconds or minutes rather than producing a normal on-cycle of 10 minutes or longer. (See COMPRESSOR CONDENSER)
• The compressor was noisy, during startup, indicating an operating problem. (See COMPRESSOR NOISES.)
• The compressor squealed at startup, indicating that service may be needed promptly to prevent possibly costly damage to the system. This repair/maintenance item should not be deferred. (See COMPRESSOR NOISES.)
• Inside cooling or evaporator coil defects that can be seen by eye: dirty coil, blocked coil, frost on the coil, improperly sized evaporator coil, improper evaporator or cooling coil placement in the system. (See AIR HANDLER UNIT.)
  Air flow across the air conditioning evaporator coil: if airflow is weak for any reason (dirty coil, duct system defects, blower fan defects, dirty blower squirrel cage fan), the air conditioning system will not operate properly. Some experts write that there should be between 350 and 400 cubic feet of air per minute (CFM) moving across the evaporator (cooling) coil for each ton of air conditioner capacity. (One ton = 12,000 BTUH so if your AC unit is a 24,000 BTUH unit it is a "two ton" unit and needs to see 700 to 800 CFM of air across the evaporator coil. Some home inspectors and air conditioning service technicians carry a small airflow meter that can actually measure this number with fair accuracy. (The same tool is nice for comparing air flow and balancing air flow at various building supply ducts and registers.
  Evaporator coil cleaning often requires cutting refrigerant lines, removal of the coil and other components for cleaning, and reinstallation, pulling a vacuum on the refrigerant lines, and recharge with refrigerant. Such service and repair may involve significant expense, although there are some "in place" cleaning methods using foams and sprays that are a simpler procedure. (See OPERATING TEMPERATURES.)
• Dirty air conditioning filters, - a source of increased operating costs. Very dirty filters can eventually block the fan itself, leading to more costly repairs. The filters should be changed monthly when the system is in use. Failure to properly filter dust from the return air supply can load the fan or evaporator coil with dust and prevent proper system operation. Installing a filter is normally a minor expense. Dirty, blocked evaporator coils can result in improper system operation, very low output temperatures, low air flow (compensated sometimes by increased fan speed), and sometimes frost on the coil and failure of system components. (See AIR HANDLER UNIT.) (See OPERATING TEMPERATURES.)
• The air conditioner operates but our electrical bills are too high. (See SEER RATINGS and see DUCT SYSTEM DEFECTS.)
• The air conditioner fuse keeps blowing or the circuit breaker trips: could mean a compressor which needs repair or replacement, or it could mean a problem with the unit's electrical wiring, such as use of aluminum wiring combined with bad electrical connections. Have your service technician check the condition of the electrical circuit first (that's cheaper than a new air conditioning compressor) and then check the condition of the compressor. See COMPRESSOR CONDENSER for air conditioner compressor diagnosis and repair; and if your air conditioning system electrical wiring is aluminum, review the aluminum wiring hazards at ALUMINUM WIRING HAZARDS & REPAIRS since a serious fire hazard could be present.

Use the links at the left side of any of our pages to find more detailed information about these and other air conditioning system defects, as well as diagnostic and repair procedures.

AIR CONDITIONING SYSTEMS Chapter Index

To continue reading this air conditioning inspection guide, use links to the document chapters at left or below. Links shown in green font indicate where you are in this document.

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