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This website answers most questions about heat pump system troubleshooting, inspection, diagnosis and repair.

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Heat Pump System Inspection, Diagnosis, Repair - List of Articles

This article describes how to inspect residential air conditioning systems (A/C systems) to inform home buyers, owners, and home inspectors of common cooling system defects. The articles at this website describe the basic components of a heat pump system, how heat pumps are inspected, diagnosed, and repaired, and we discuss how to estimate the rated heating and cooling capacity of a heat pump system by examining various data tags and components. The limitations of visual inspection of HVAC systems are described. The schematic of a heat pump system shown above is compliments of Carson Dunlop.

Also see AIR CONDITIONING & HEAT PUMP SYSTEMS where we introduce and illustrate the basic components of air conditioners and heat pumps.

Since most components of a heat pump system are identical with those of central air conditioning systems, readers should also be sure to review our air conditioning system inspection, diagnosis, and repair articles.

• AIR CONDITIONER NOT WORKING - also helps diagnose heat pump not working
• APPLIANCE EFFICIENCY RATINGS - how efficient is your heat pump? also see SEER RATINGS & OTHER DEFINITIONS
• BACKUP HEAT for HEAT PUMPS - types of backup heat, diagnosing back up heat pump heat not working properly
• HEAT PUMPS, GROUNDWATER - what are the COP's and EER's of groundwater based heatpump systems?
• A/C - HEAT PUMP CONTROLS & SWITCHES - for air conditioning and heat pump systems
• ENERGY USE MONITORING - tracking energy use to see where to save on heating or cooling costs
• HEAT PUMP STRATEGY - Indoors? - can we locate a heat pump or water heating heat pump indoors to scavenge heat?
• HEATING COST SAVINGS METHODS - how to save on heat, including ENERGY SAVINGS PRIORITIES
• FAN AUTO ON Thermostat Switch - make sure it's turned on to the proper setting
• HEAT PUMP Thermostats - Outdoors - failures in an outdoor component can cause odd heat pump operation or noises
• LOST COOLING CAPACITY - why are we not getting adequate cooling or heating from our heat pump?

Heat Pump Stopped Heating or Cooling - Diagnostic Guide

If your heat pump system has lost its cooling capacity or won't start select one or more of the diagnostic articles listed below.

• A/C REFRIGERANT LEAK DETECTION: how to use a TIF5000 to detect air conditioning refrigerant gas leak
• A/C DIAGNOSTIC FAQs: air conditioning system diagnostic FAQs: Q&A about air conditioner repair - a detailed air conditioning system diagnostic checklist
• AIR HANDLER UNIT: problems with the air handler, air filters, and the cooling coil itself
• BACKUP HEAT: on heat pumps, types of backup heat; problems with backup heat; begin here if your heat pump is not providing enough heat or if your air conditioning system provides heat when it should be providing cooling.
• COMPRESSOR CONDENSER: problems with air conditioner compressor/condenser units including noises and compressor hard-starting repairs
• A/C - HEAT PUMP CONTROLS & SWITCHES: air conditioner controls and switches - begin here if your A/C won't start. Here's an important tip: most refrigeration problems, in air conditioners, refrigerators, or freezers, are electrical, not mechanical. In air conditioning school, we used to drive out and collect abandoned refrigerators that people were tossing out during our community's spring cleanup week. Taking these appliances back into the shop we found that almost always the problem that had caused the owner to dispose of their air conditioner or freezer was in an electrical connection or electrical control. So it's worth checking out switches and controls on an air conditioner before replacing more costly components.
• Dehumidification Problems - Air conditioner cools but does not dehumidify
• DUCT SYSTEM DEFECTS: problems with the air duct system, air filters, supply registers, return air registers
• Fire dampers, and Heating and Cooling Air Duct Controls such as manual and automatic duct dampers, zone dampers, and fire dampers are discussed and distinguished at DRAFT REGULATORS - barometric damper
• LOST COOLING CAPACITY: what to do when not enough cool air comes out of the system - the articles in this series also assist in diagnosis of lost heating capacity for heat pump systems.
  • What to check first if there is no cool air or not enough cool air
  • Compressor failure diagnosis: basic checks of the air conditioner compressor
  • Ducts & Air Handler diagnosis: basic checks of the indoor air handler (blower), air ducts, and filter system
• OPERATING DEFECTS: major air conditioning problem symptoms and how to get the air conditioning system working again,e.g. compressor or fan noises, failure to start, and inadequate cool air volume
• ZONE DAMPER CONTROLS . discusses manual and automatic air duct zone controls

Questions & Answers regarding this article

Questions & answers about how to diagnose & repair residential heat pump systems

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Technical Reviewers & References

• InspectAPedia.com^® - Daniel Friedman - Publisher & Editor.
• InspectAPedia Bookstore lists recommended books, organized by topic & available for purchase. Most of our articles also include a list of recommended books for the specific article topic as well as other references, and information sources.
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• Additional technical contributors & reference sources for this article are listed below.

Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

DIAGNOSE & FIX AIR CONDITIONER / HEAT PUMP

HEAT LOSS (or GAIN) in buildings
HEAT PUMPS
  BACKUP HEAT for HEAT PUMPS
  HEAT PUMP Thermostats - Outdoors

LOST COOLING CAPACITY
  What to Check First
  A/C Flow Too Weak
  A/C Filter Problems
  A/C Compressor Problems
  A/C Off - Condensate Pan Switch
  A/C Cooling Coil Icing
  A/C Not Dehumidifying
  A/C Air Duct Problems
  Air Conditioner Won't Start
  Air Conditioner Refrigerant Problems
  Blower Fan No Start / No Stop
  Compressor Diagnosis: Diagnose & Repair
  Cooling Capacity of the Duct System
  Repair Guide Master List

MANUALS & PARTS GUIDES - HVAC
MOTOR OVERLOAD RESET SWITCH

NOISY AIR CONDITIONER / HEAT PUMP

OPERATING COST
OPERATING DEFECTS
OPERATING TEMPERATURES
  Air Conditioning System Temperatures
  Instruments Used to Measure A/C Temperatures
  Procedures for Making Temperature Measurements

• Thanks to Mark 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.
• Thanks to Neal Renn who described diagnosing the problem of a heat pump that "only gets backup heat and no cooling" to describe the problem of a heat pump that insists on turning on backup heat when it is not needed.
• Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. Thanks to Alan Carson and Bob Dunlop, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education including the ASHI-adopted Home Inspection Training Program (home study course), publications such as the Home Reference Book, report writing materials including the Horizon report writer, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
• Thanks also to Alan Carson, Carson Dunlop, Associates, Toronto, for technical critique and for providing a copy of Carson Dunlop Weldon & Associates Technical Reference Guide to manufacturer's model and serial number information for heating and cooling equipment ($69.00 U.S.).
• Geothermal HVAC, [Amazon.com] Jay Egg & Brian Howard, McGraw-Hill Professional; ISBN-10: 0071746102, ISBN-13: 978-0071746106, quoting:
  
  This definitive guide covers commercial and residential geothermal heating, ventilation, and air conditioning technologies and explains how to take advantage of their money- and energy-saving features. Geothermal HVAC: Green Heating and Cooling reviews the array of choices currently available, offers market values for systems based on varying options and conditions, and describes how to pair the best systems for each application and budget. Whether you're a contractor or a consumer, you'll find out what you need to know to implement a geothermal HVAC system in a retrofit or new construction project, and start benefiting from this sustainable, affordable technology.
• Geothermal Heat Pumps: A Guide for Planning and Installing, [Amazon.com], Karl Ochsner, Robin Curtis, Earthscan Publications Ltd. (December 2007), ISBN-10: 1844074064, ISBN-13: 978-1844074068quoting:
  
  Geothermal Heat Pumps is the most comprehensive guide to the selection, design and installation of geothermal heat pumps available. This leading manual presents the most recent information and market developments in order to put any installer, engineer or architect in the position to design, select and install a domestic geothermal heat pump system. Internationally respected expert Karl Ochsner presents the reasons to use heat pumps, introduces basic theory and reviews the wide variety of available heat pump models. Expertly reviewed and adapted for the most geographically broad application possible, the book offers the reader valuable tips for planning and system control using data, graphics and tables from a growing and innovative market.
• Residential Geothermal Systems: Heating And Cooling Using The Ground Below, [Amazon.com], John Stojanowski, Pangea Publications LLC (March 17, 2010) ISBN-10: 0981922112, ISBN-13: 978-0981922119. Quoting from Amazon.com reviews:
  

  Readers will learn how heat pumps are able to extract heat from relatively low temperature water circulating in ground loops and raise it to a temperature high enough to heat a home. They will also learn how to estimate the size of the heat pump required and the ground loop size as well for straight 2-pipe, 4-pipe, 6-pipe and Slinky loop configurations. This is important in order to verify that the installer correctly sizes the system. Both horizontal and vertical loop systems, for GX and DX, are covered.

  Some of the technical issues that are addressed include: Loop water flow rates and Reynolds Number, heat of extraction/rejection, heating capacity, desuperheater setup, open-loop/closed-loop, SCW, pond loops, DX, Manual-J, COP. The final chapter consists of a set of flowcharts guiding the homeowner to ask the pertinent questions needed for a successful installation.

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

• 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 ($69.00 U.S.).
• Air Conditioning Inspection, Diagnosis, Repair, Efficiency all the basics for home owners, inspectors, new repairmen
• Air 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