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AIR CONDITIONING & HEAT PUMP SYSTEMS

A/C - HEAT PUMP CONTROLS & SWITCHES
A/C DATA TAGS
A/C - HEAT PUMP CRITICAL DEFECTS
A/C DIAGNOSTIC FAQs
A/C REFRIGERANTS
A/C TYPES, ENERGY SOURCES
AGE of AIR CONDITIONERS & HEAT PUMPS
AGE of HEATERS, BOILERS, FURNACES
AGE of WATER HEATERS
AIR CONDITIONER BTU CHART
AIR CONDITIONER COMPONENT PARTS
AIR CONDITIONER TYPES, ENERGY SOURCES
AIR CONDITIONER NOT WORKING
AIR FILTER EFFICIENCY
AIR FILTERS, FIBERGLASS PARTICLES
AIR FILTERS for HVAC SYSTEMS
AIR FLOW MEASUREMENT CFM
AIR HANDLER / BLOWER UNITS
ANIMAL ALLERGENS / PET DANDER
ANIMAL ENTRY POINTS in buildings
ANIMAL ODORS IN buildings
APPLIANCE EFFICIENCY RATINGS
ASBESTOS IDENTIFICATION IN buildings

BACKUP HEAT for HEAT PUMPS
BLOWER DOORS & AIR INFILTRATION
BLOWER FAN CONTINUOUS OPERATION
BLOWER FAN OPERATION & TESTING
BOOKSTORE - Air Conditioning "How To" Books

CAPACITORS for HARD STARTING MOTORS
CAPILLARY TUBES
CHINESE DRYWALL HAZARDS
CIRCUIT BREAKER SIZE for A/C or HEAT PUMP
CLEANING & Legionella BACTERIA
CHINESE DRYWALL HAZARDS
COMBUSTION GASES & PARTICLE HAZARDS
COMPRESSOR & CONDENSING COIL, A/C
CONDENSATE HANDLING, A/C
CLEANING & Legionella BACTERIA

DEW POINT TABLE - CONDENSATION POINT GUIDE
DIAGNOSE & FIX AIR CONDITIONER / HEAT PUMP
DUCT SYSTEM & DUCT DEFECTS
DUCTS - Asbestos

DUST, HVAC CONTAMINATION STUDY
DUST SAMPLING PROCEDURE

EDUCATION, HVAC SCHOOLS
ELECTRIC MOTOR DIAGNOSTIC GUIDE
ELECTRIC MOTOR OVERLOAD RESET SWITCH
ELECTRICAL POWER SWITCH FOR HEAT
EVAPORATOR COIL or COOLING COIL
EVAPORATIVE COOLING SYSTEMS
EVAPORATOR COIL or COOLING COIL
EXPANSION VALVES, REFRIGERANT

FAN, AIR HANDLER BLOWER UNIT
FAN AUTO ON Thermostat Switch
FURNACES WARM AIR HEATING SYSTEMS

GAS EXPOSURE EFFECTS, TOXIC
GAS DETECTION INSTRUMENTS
GAUGE, REFRIGERATION PRESSURE TEST

HEAT LOSS (or GAIN) in buildings
HEAT LOSS (or GAIN) INDICATORS
HEAT LOSS R U & K VALUE CALCULATION
HEAT PUMPS
HEATING SMALL LOADS
HOUSEWRAP AIR & VAPOR BARRIERS
HUMIDITY LEVEL TARGET

INDOOR AIR QUALITY IMPROVEMENT GUIDE
INSPECTION CHECKLIST - OUTDOOR UNIT
INSPECTION LIMITATIONS, A/C SYSTEMS

LIGHT, GUIDE to FORENSIC USE
LOST COOLING CAPACITY
LOW VOLTAGE TRANSFORMER TEST

MANUALS & PARTS GUIDES - HVAC
MOTOR OVERLOAD RESET SWITCH
MOLD in AIR HANDLERS & DUCT WORK
MOLD INFORMATION CENTER

NOISE AIR CONDITIONER / HEAT PUMP
NOISE / SOUND DIAGNOSIS & CURE

ODORS in AIR HANDLERS & DUCT WORK
ODORS in AIR HANDLERS & DUCT WORK
OPERATING COST, AIR CONDITIONER
OPERATING DEFECTS, AIR CONDITIONING
OPERATING TEMPERATURES, AIR CONDITIONER

PORTABLE ROOM AIR CONDITIONERS
PRESSURE READINGS, REFRIGERANT

REPAIR GUIDE, AIR CONDITIONERS / HEAT PUMPS
REPAIR & DIAGNOSTIC FAQs for A/C
REFRIGERANTS & PIPING
RETROFIT SIZING for A/C or HEAT PUMPS

SEER RATINGS & OTHER DEFINITIONS
SPLIT SYSTEM AIR CONDITIONERS & HEAT PUMPS
SWAMP COOLERS
SYSTEM OPERATION

THERMOSTATS, HEATING / COOLING
THERMOSTATIC EXPANSION VALVES

WATER COOLED AIR CONDITIONERS
WINDOW / WALL AIR CONDITIONERS
WINDOW / WALL A/C SUPPORTS

More Information

Photograph of  this unusual attic air conditioning system is an example of
the range of human creativity observed during a career of building inspections Checklist of Critical Defects in Air Conditioning or Heat Pump Systems
     

  • A/C - HEAT PUMP CRITICAL DEFECTS - Air Conditioning (or Heat Pump) Critical Defects are listed here
  • List of A/C problems that can be observed by visual inspection
  • Examples of A/C or heat pump problem reporting language for inspection reports
  • DEFECTS LIST - AIR CONDITIONING - separate article
  • BUILDING DEFECTS LISTS - separate article
  • A/C INSPECTION CHECKLIST - OUTDOOR UNIT - separate article
  • A/C INSPECTION LIMITATIONS - separate article
  • Questions & Answers about spotting & reporting critical defects in air conditioners or heat pumps
  • References

Click to Show or Hide Related Topics

  • AIR CONDITIONING & HEAT PUMP SYSTEMS - home
  • A/C COMPONENTS
  • AIR FILTERS for HVAC SYSTEMS
  • AIR HANDLER / BLOWER UNITS
  • BACKUP HEAT for HEAT PUMPS
  • BTU CHART for AIR CONDITIONERS / HEAT PUMPS
  • CLEARANCE DISTANCE, HVAC
  • COMPRESSOR & CONDENSING COIL, A/C
  • CONDENSATE HANDLING, A/C
  • CONTROLS & SWITCHES, A/C - HEAT PUMP
  • CONDENSING COIL REPAIR REPLACE
  • COOL OFF HEAT THERMOSTAT SWITCH
  • COOLING CAPACITY, RATED
  • COOLING COIL or EVAPORATOR COIL
  • COOLING COIL CLEANING
  • DATA TAGS on AIR CONDITIONERS
  • DEHUMIDIFICATION PROBLEMS
  • DUCT SYSTEM & DUCT DEFECTS
  • DUCTLESS AIR CONDITIONERS & HEAT PUMPS
  • EDUCATION & CLASSES, HVAC SCHOOLS
  • ELECTRIC MOTOR DIAGNOSTIC GUIDE
  • EXPANSION VALVES, REFRIGERANT
  • FAN, AIR HANDLER BLOWER UNIT
  • FAN AUTO ON Thermostat Switch
  • FAN, COMPRESSOR/CONDENSER UNIT
  • FAN CONVECTOR HEATERS - HYDRONIC COILS
  • FROST BUILD-UP on AIR CONDITIONER COILS
  • GAUGE, REFRIGERATION PRESSURE TEST
  • HEAT PUMPS
  • HUMIDITY LEVEL TARGET
  • MANUALS & PARTS GUIDES - HVAC
  • MINI SPLIT AIR CONDITIONERS & HEAT PUMPS
  • NOISE AIR CONDITIONER / HEAT PUMP
  • ODORS in AIR HANDLERS & DUCT WORK
  • OPERATING TEMPERATURES
  • PORTABLE ROOM AIR CONDITIONERS
  • PRESSURE READINGS, REFRIGERANT
  • REFRIGERANTS & PIPING
  • REPAIR GUIDE - A/C or Heat Pumps
  • REPAIR TOPICS A/C & HEAT PUMPS
  • ROOFTOP A/C / HEAT PUMP
  • SEER RATINGS & OTHER DEFINITIONS
  • SPLIT SYSTEM Ductless Air Conditioners
  • SWAMP COOLERS
  • THERMOSTATS, HEATING / COOLING
  • THERMOSTATIC EXPANSION VALVES
  • WALL CONVECTORS Heating / Cooling
  • WINDOW / WALL AIR CONDITIONERS
InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

Air conditioner defect checklist: here we list the types of critical problems that may occur in air conditioning or heat pump systems, a first step in understanding how an air conditioning service technician will diagnose certain common air conditioning system failures or defects. This air conditioning/heat pump inspection guide lists critical air conditioning system defects which a building inspector or owner should not miss. We include photographs to assist readers in recognizing cooling system defects. This HVAC article series describes the inspection, diagnosis & repair of residential air conditioning systems (A/C systems) & heat pump systems to diagnose problems as well as to inform home buyers, owners, and home inspectors of common cooling system defects.

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

Critical Defects in Air Conditioning Equipment Inspections

Beginning at AIR CONDITIONING & HEAT PUMP SYSTEMS the major components of an air conditioning system are described, sketches and photographs are provided, and common defects for each cooling system component are listed along with visual or other clues that may suggest a problem or probable failure of A/C components.

Example home inspection report language used to report air conditioning system defects and cooling system repairs needed is provided to describe common air conditioning system defects. We continue to add to and update this text as new details are provided. Contact us to suggest text corrections or additions and, if you wish, to receive online listing and credit for that contribution.

Critical defects which an inspector should not fail to detect when examining any building component or system are defects which form an immediate, significant safety hazard or defects which are quite likely to involve significant repair or replacement cost, and which involve components or systems which are necessary to occupy and use the building. Methods for detection and diagnosis of these defects are discussed in this document and in its references. Suggestions for inclusion or exclusion of items in this list are invited - see the link "Contact Us".

  • Function: Air conditioning compressor needs replacement. See COMPRESSOR & CONDENSING COIL and see LOST COOLING CAPACITY
  • Function: Cooling is delivered to only part of the building, e.g. only to one floor. See DUCT SYSTEM DEFECTS
  • Air Duct System Safety: Unsafe return air intake which may draw in carbon monoxide at heating equipment. See DUCT SYSTEM DEFECTS. Note that more indirect building defects and hazards, such as a toxic airborne mold reservoir or toxic gases or chemicals (such as sewer gas) may be picked up and distributed through a building from one area to another by duct system defects.
  • Uneven air supply resulting in uneven temperatures especially on the first floor of a two story house with ductwork between the first and second floor. See DUCT SYSTEM DEFECTS
  • Inadequate cooling capacity for building. See LOST COOLING CAPACITY
  • Low temperature split (indicating inadequate cooling due to refrigerant leak). See A/C REFRIGERANTS and see COOLING COIL or EVAPORATOR COIL
  • Refrigerant leaks at condenser or evaporator coils (usually requires replacement of coil.) See A/C REFRIGERANTS
  • Dirty air handler. (Major expense to clean properly.) See AIR HANDLER / BLOWER UNITS and see AIR FILTERS for HVAC SYSTEMS
  • Leaking return ducts in crawl space. See DUCT SYSTEM DEFECTS
  • Air Conditioning System Safety: Unsafe electrical wiring: aluminum branch circuits and FPE Stab-Lok or Zinsco circuit breakers may have been used to power the compressor. Look for evidence of overheating or over fusing at the service cutoff and in the electrical panel and at the service cutoff by the compressor/condenser [This item is not agreed-on as a critical defect by all reviewers] For details see:
    • ALUMINUM WIRING HAZARDS - aluminum electrical wiring often burns-up at high-amperage electrical connections such as air conditioner wiring.
    • Federal Pacific Electric (FPE) FPE Stab-Lok Circuit Breakers can increase the risk of a fire if these breakers are used on air conditioning or heat pump equipment
    • Zinsco Electrical Circuit Breakerss: overheating, failure to trip, burn-ups involving Zinsco and certain Sylvania electrical panel components. These components can also increase the risk of a fire if these breakers are used on air conditioning or heat pump equipment

Air Conditioning System Operation Report Language

Observation of the condition of an air conditioning or heat pump system, typical inspection report language includes these succinct descriptions of findings:
... The cooling system operated normally at the time of our inspection.
... Caution: The equipment was not run and therefore not tested
... because
... outside temperature was estimated to be at or below 50 degF.
... the system has been "shut down" for some time.
... In cold weather operation could damage the compressor, particularly if it has been left "shut down".
... Individual components were not operated - see note below.
... Any deficiencies noted were based only on visual inspection. We did no
... electrical, gauge or pressure tests on this equipment.

Operating Note: Many such air conditioning systems must be left with power turned on (we found switches in the "off" position) for 24 hours prior to running the equipment. This permits heaters at the compressors to assure good oil flow in those components. To operate the equipment without this step risks very costly damage to the compressor. When a system is not operated we can make no representation that it functions correctly and adequately.


... We recommend that you ask the owner about the condition of this equipment.


... If weather permits, it should be checked by an HVAC service person and returned to operating status prior closing sale.


Frequently Asked Questions (FAQs)

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Technical Reviewers & References

Related Topics, found near the top of this page suggest articles closely related to this one.

Click to Show or Hide Citations & References

  • Thanks to AMark Cramer, Tampa Florida, for assistance in technical review of the "Critical Defects" section and for the photograph of the deteriorating gray Owens Corning flex duct in a hot attic. Mr. Cramer is a Florida home inspector and home inspection educator.
  • Modern Refrigeration and Air Conditioning, A. D. Althouse, C.H. Turnquist, A. Bracciano, Goodheart-Willcox Co., 1982
  • Principles of Refrigeration, R. Warren Marsh, C. Thomas Olivo, Delmar Publishers, 1979
  • "Air Conditioning & Refrigeration I & II", BOCES Education, Warren Hilliard (instructor), Poughkeepsie, New York, May - July 1982, [classroom notes from air conditioning and refrigeration maintenance and repair course attended by the website author]
  • Refrigeration and Air Conditioning Technology, 5th Ed., William C. Whitman, William M. Johnson, John Tomczyk, Cengage Learning, 2005, ISBN 1401837654, 9781401837655 1324 pages
  • Carson Dunlop, Associates, Toronto, have provided us with (and we recommend) Carson Dunlop Weldon & Associates' Technical Reference Guide to manufacturer's model and serial number information for heating and cooling equipment
    Special Offer
    : Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.

  • NewAir Conditioning SEER - New DOE Air Conditioner and Heat Pump Efficiency Standard
  • Asbestos HVAC Ducts and Flues field identification photos and guide
  • Fiberglass: Indoor Air Quality Investigations: Fiberglass in Indoor Air, HVAC ducts, and Building Insulation

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

  • Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
  • Home Reference Book - Carson DunlopThe Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.

    Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.

  • GO TO Carson Dunlop's Home Study Course Information - How to Become a Home Inspector: Carson Dunlop's nationally recognized Home Study Course, selected by ASHI the American Society of Home Inspectors and other professionals and associations. This website author is a contributor to this course.
  • GO TO Carson Dunlop's Home Study Course Information - How to Become a Home Inspector: Carson Dunlop's nationally recognized Home Study Course, selected by ASHI the American Society of Home Inspectors and other professionals and associations. This website author is a contributor to this course.
  • GO TO Carson Dunlop's Home Study Course Information - How to Become a Home Inspector: Carson Dunlop's nationally recognized Home Study Course, selected by ASHI the American Society of Home Inspectors and other professionals and associations. This website author is a contributor to this course.
    Building inspection education & report writing systems from Carson, Dunlop & Associates Ltd
  • Carson Dunlop, Associates, Toronto, have provided us with (and we recommend) Carson Dunlop Weldon & Associates' Technical Reference Guide to manufacturer's model and serial number information for heating and cooling equipment
    Special Offer
    : Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.

  • Complete List of Air Conditioning & Heat Pump Design, Inspection, Repair Books at the InspectAPedia Bookstore.
  • ...
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