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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
CIRCUIT BREAKER SIZE for A/C or HEAT PUMP
CLEANING & Legionella BACTERIA
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
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
WATER COOLED AIR CONDITIONERS
Air conditioner & heat pump controls & switches: this article explains the function, location, identification & use of all air conditioning & heat pump system operating controls. Photos and text help you to find & recognize each of these controls and the text explains what the control does. We include links to detailed diagnosis & repair articles related to the various HVACR controls & swtiches. We also review the basic air conditioning safety switches, contactors, relays, refrigerant metering devices, motor overolad switches, relays, resets.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
List & Purpose of All of the Air Conditioning & Heat Pump System Operating & Safety Controls
Also see A/C - HEAT PUMP CONTROLS & SWITCHES where we list all Air Conditioning & Heat Pump System Controls & Switches, and see THERMOSTATS. This chapter is part of our 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.
If your air conditioning or heat pump system has lost its cooling capacity or won't start see REPAIR GUIDE for AIR CONDITIONERS. See How to determine the cooling capacity of air conditioning equipment if the system seems to be working but is inadequate to cool your building. Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.
Basic air conditioning inspection and inspection report information for A/C controls:
SAFETY CONTROLS - Air Conditioning Automatic Safety Controls - Cooling System Fuse or Circuit Breaker Size Requirements
Electric Power Controls - Safety Disconnects for Air Conditioners
How to Specify the Breaker or Fuse Size for Air Conditioning Circuits
As we explained at the beginning of this document, a hermetic compressor draws varying amounts of current (measured in amps) as its internal pressure changes during operation. We said that current draw is higher when starting the motor than when the system is in steady state operation.
Current draw is highest if the motor is starting against its highest back pressure such as if the air conditioning system has been turned off and then back on in the middle of operation. Because fusing an air conditioning compressor at the minimum level can result in blown fuses or tripped breakers during these intervals of heavy current draw during compressor startup, compressors are either protected by a slow-blow fuse or a somewhat larger than minimum circuit breaker.]
Rules of thumb for over sizing air conditioning system breakers or fuses:
On some older equipment MOP is not specified. Only when MOP has not been specified can the overcurrent protection required be determined by alternative means such as [RLA OR BCSC whichever is greater x 175%], or if the compressor keeps tripping that device or blowing that fuse, RLA x 225% might be used.
The National Electrical Code (NEC) specifies the degree to which a breaker or fuse may exceed the RLA. [For example, if the MOP or fuse size is specified by the manufacturer to be 40 amps, then a 40 amp breaker must be installed with no increase or change in that rating.]
Multiple switches are often present on cooling systems. As we reminded in the previous chapter, if the air conditioning system won't run, before requesting a service call check all of the switches as well as the thermostat for proper settings.
Air Conditioner Fuse or Circuit Breaker Size Details
Frequently Asked Questions (FAQs)
Questions & answers or comments about finding, using, repairing, or replacing air conditioner or heat pump controls & switches.
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Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.