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AIR CONDITIONING & HEAT PUMP SYSTEMS
A/C - HEAT PUMP CONTROLS & SWITCHES
AIR CONDITIONER COMPONENT PARTS
AIR CONDITIONER TYPES, ENERGY SOURCES
AIR FILTER EFFICIENCY
AIR FILTERS, FIBERGLASS PARTICLES
AIR FLOW MEASUREMENT CFM
APPLIANCE EFFICIENCY RATINGS
BLOWER DOORS & AIR INFILTRATION
BLOWER FAN CONTINUOUS OPERATION
BLOWER FAN OPERATION & TESTING
BOOKSTORE - Air Conditioning "How To" Books
CAPACITORS for HARD STARTING MOTORS
CLEANING & Legionella BACTERIA
CHINESE DRYWALL HAZARDS
CONDENSATION or SWEATING PIPES, TANKS
DEFINITION of Heating & Cooling Terms
DEW POINT CALCULATION for WALLS
DEW POINT TABLE - CONDENSATION POINT GUIDE
DIAGNOSE & FIX AIR CONDITIONER / HEAT PUMP
DIAGNOSE & FIX HEATING PROBLEMS-BOILER
DIAGNOSE & FIX HEATING PROBLEMS-FURNACE
DUCTS - Asbestos
DUCT INSULATION, Asbestos Paper
DUCT INSULATION for SOUNDPROOFING
DUCT SYSTEM NOISES
DUCTS, Asbestos Transite Pipe
DUST, HVAC CONTAMINATION STUDY
ELECTRIC MOTOR OVERLOAD RESET SWITCH
EVAPORATIVE COOLING SYSTEMS
FAN LIMIT SWITCH
GAS EXPOSURE EFFECTS, TOXIC
GAS DETECTION INSTRUMENTS
HEAT LOSS (or GAIN) in buildings
HEAT LOSS (or GAIN) INDICATORS
HEAT LOSS R U & K VALUE CALCULATION
HEATING SMALL LOADS
INSPECTION CHECKLIST - OUTDOOR UNIT
INSPECTION LIMITATIONS, A/C SYSTEMS
LEED GREEN BUILDING CERTIFICATION
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 GUIDE, AIR CONDITIONERS / HEAT PUMPS
REPAIR & DIAGNOSTIC FAQs for A/C
THERMOSTATS, HEATING / COOLING
THERMOSTATIC EXPANSION VALVES
WATER COOLED AIR CONDITIONERS
WINDOW / WALL AIR CONDITIONERS
WINDOW / WALL A/C SUPPORTS
WATER HEATER SAFETY
WATER HEATERS for HOME HEATING USE?
WATER HEATER NOISES
WATER HEATER SCALE - De-Liming Procedure
WATER HEATER SCALE PREVENTION
WATER SOFTENERS & CONDITIONERS
WINTERIZE A BUILDING
WOOD, COAL STOVES & FIREPLACES
WOOD STOVE SAFETY
Guide to ductless split-system air conditioners: This article describes split system air conditioning & heat pump systems. We review the major system components, switches & controls, and typical applications for split system cooling systems, and we discuss use of the remote thermostat control, where to find and how to clean the split system air filters, how condensate is disposed-of, and what to check first if your split system air conditioner is not working properly.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
Split System Air Conditioner & Heat Pump Systems: controls, operation, diagnosis, repair & component parts guide
A split system or "ductless" air conditioning (or A/C & heat pump) system dispenses with duct work entirely, using a wall-mounted indoor evaporator/blower unit and a separate outside compressor/condenser (below left and right). In this split system air conditioning design, one compressor/condenser may serve multiple wall-mount indoor units.
The ductless or split and mini-split system air conditioners used in our illustrations are Sanyo brand, but there are quite a few split system and split system mini air conditioners currently on the market, including models by Carrier, Friedrich, Frigidaire, Goodman, LG, Mitsubishi, Panasonic, Sanyo, and Samsung. The basic components, installation, and maintenance procedures here apply to all types of mini split system or ductless A/C and heat pump units, but of course you should also read the manufacturer's installation and users' guide for your unit as well.
This website discusses these air conditioning and heat pump terms and problems: Air Conditioners: Central Air Conditioning Troubleshooting & Repair Guide: How to Inspect, Diagnose, & Repair Central Air Conditioning: Defects in A/C compressors, air handlers, duct work, and controls. We explain how to inspect & repair central air conditioning systems and for homeowners we also answer basic HVAC questions such as what are the basic air conditioning components? We provide guidance in determining air conditioning cooling capacity & energy efficiency, Troubleshooting air conditioning compressor problems, Diagnosing air conditioning air handler problems, Air conditioning condensate problems, Duct system inspections, defects, repairs, Cleaning air conditioning equipment & A/C refrigerants.
Split system air conditioners and heat pumps may use a remote control device to turn the equipment on or off and to set the desired temperature. You will also find some operating switches and controls on the indoor wall-mounted cooling unit air handler, for most split system cooling units and heat pumps, the user is expected to use the remote control.
Remote control thermostats such as the unit shown at left are usually used with air conditioning or heating split systems using an outside compressor/condenser unit and one or more indoor wall-mounted cooling or heating units..
The thermostat controls in the hand-held remote control communicates with a wall-mounted air conditioner or heater using infra red signals. The open finned area at the bottom of the remote A/C control (at the left in our photo) permit ambient air to enter the control for purpose of sensing the air temperature.
A control such as this Sanyo (TM) unit can be quite sophisticated and include automatic set back temperatures, timers, etc.
On the remote control for a split system A/C or heat pump unit there are typically two levels of operating controls or settings.
Also see THERMOSTATS. And at A/C - HEAT PUMP CONTROLS & SWITCHES we describe all of the controls and switches found on residential and most commercial air conditioning and heat pump systems. Other controls that affect a split system air conditioner or heat pump will include
You can see the outdoor service switch (circled in red) in our photo at left. Depending on the installation, this box may contain fuses, a circuit breaker, or a simple pull-out that can kill power to the unit.
If your split system A/C unit is not cooling, remember to check this switch to be sure that power is being delivered to the unit.
Watch out: at installations using aluminum wire to bring power to the outside compressor/condenser unit the electrical connections between the aluminum wire and the lugs inside the service switch can fail, leading to overheating, loss of cooling, repeated cooling outages, and even an electrical fire. Extra care in making aluminum wire connections such as using an approved antioxidant and proper connection torquing significantly reduce this hazard. Details are at ALUMINUM WIRING HAZARDS & REPAIRS.
Split System Air Conditioner Air Filter Maintenance - How to Clean a Split System Air Conditioner 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.
We took two photos (shown below) of a pair of washable air filters pulled from the indoor cooling unit of a wall mounted split-system air conditioner used in our lab.
Holding up the two washable air filters and trying to peer through them, even in the dim afternoon light, that the clean filter (on the right) is almost transparent, while the dirty air filter (at left in our photo) is completely opaque.
This simple visual test can confirm the state of a washable air filter.
Watch out: these washable filters are pretty tough, but we offer these additional care recommendations:
Take care not to tear or damage the filter screen. Torn, the air filter will allow dust and debris to accumulate in the cooling system - leading to reduced cooling, frost or ice formation, and eventually the cost of a professional cleanup job.
The plastic filter is much thinner than the larger pleated paper or fiberglass filters used in the air handler of central air conditioning systems or heating furnaces. That means the filter should be inspected and cleaned with diligence - monthly during a season of daily use would be smart.
Additional ultrafine particulate filters on some Split System A/C and Heat Pump Units
Some split system air handlers include an extra internal filter intended to reduce ultrafine particulates such as from tobacco smoke. These filters are optional and might slightly reduce the air output from the unit. Fujitsu advises as follows:
Watch out: if you take a look at this filter you'll see it looks like fragile cardboard - it is not washable but rather is a disposable filter that is replaced as needed.
Some split system air handlers also include a negative ion generation feature also intended to remove some odors and ultra fine particulates from the air flow. Quoting:
The negative ions system includes an internal filter sheet that should be replaced every few years. (Say 3 year intervals). 
Fujitsu provides some helpful advice about troubleshooting weak air flow from the indoor wall-mounted component of a split system air conditioner or heat pump. The following are adapted from that source: 
Causes of no air flow or very very weak air flow from the A/C - heat pump unit
Causes of weak air flow from the wall-mounted split system A/C or heat pump
How to diagnose poor or inadequate cooling or heating from a split system air conditioner or heat pump
Frequently Asked Questions (FAQs) about split system A/Cs or heat pumps
Question: it looks as if smoke or steam is coming out of our wall-mounted split system air conditioner/heat pump
We saw smoke or maybe it was steam (since it didn't smell) coming out of our wall-mounted split system air conditioner/heat pump - is this dangerous? - Anon.
Fujitsu has pointed out that at least on their mini split system heat pump/air conditioner wall mounted units a white steam coming from the air handler indoors may be perfectly normal. 
Reply: How to fix or replace a remote control thermostat control for an air conditioners or heat pump
A remote control air conditioner thermostat (like the one in our photo) control communicates with a wall-mounted air conditioner or heater using infra red signals. The open finned area at the bottom of this Sanyo control (at the left in our photo) permits ambient air to enter the control for purpose of sensing the air temperature. A control such as this Sanyo™ unit can be quite sophisticated and include automatic set back temperatures, timers, etc. About how to diagnose and fix an air conditioner remote control unit:
Replacing the hand-held remote control for an A/C system:
If you mean that you need to replace the hand-held portable remote control for your air conditioner, a new unit is best bought from the manufacturer themselves as that assures complete compatability with all of your air conditioners features.
How to troubleshoot & fix an air conditioner or heat pump remote control
If you mean that you think the remote control problem is inside of the wall-mounted A/C of a split system air conditioner or heat pump then I have some different advice. Basically, since the problem is usually in the hand held control unit, start there with these diagnostic and maintenance tips:
Check the remote control batteries: Start with replacing the remote control's batteries, then turning it back on and testing it's ability to control the A/C unit.
Watch out: a simple mistake like putting the batteries into the remote control with the (+) and (-) ends pointing the wrong way is enough to keep the control from working.
Check the air sensor port on the remote control and the control resting location: if the remote control seems to communicate with the wall unit but temperature response is not what you want, check that the openings that allow room air to enter the remote control are not blocked with dust or debris. Also consider where you are leaving the remote control. If you place the control directly in the cool air path of the A/C unit it will be "satisfied" sooner than you may wish. If you place the remote control too far away, out of the room, or in a dead air space or under a magazine, clearly it's not going to be able to respond well to the actual room temperature.
Also see THERMOSTATS, HEATING / COOLING.
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