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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 DIAGNOSIS & REPAIR
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
DIAGNOSTIC GUIDES A/C / HEAT PUMP
DIAGNOSE & FIX HEATING PROBLEMS-BOILER
DIAGNOSE & FIX HEATING PROBLEMS-FURNACE
DUCTS - Asbestos
DUCT INSULATION, Asbestos Paper
DUCT INSULATION for SOUNDPROOFING
DUCT SYSTEM & DUCT DEFECTS
DUCT SYSTEM NOISES
DUCTS, Asbestos Transite Pipe
DUST, HVAC CONTAMINATION STUDY
ELECTRIC MOTOR OVERLOAD RESET SWITCH
EVAPORATIVE COOLING SYSTEMS
FAN LIMIT SWITCH
FAN NOISES, HVAC
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 GUIDES A/C / HEAT PUMP
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
A/C or heat pump compressor/condenser unit installation mistakes: this air conditioning repair article discusses the installation errors in air conditioning compressor and condensing units such as improper location, blocked air flow, out of level, or not properly supported. We discuss required equipment clearance distances, refrigerant line piping support and routing, and problems with shrubbery or other air flow blockages that can cause overheating, higher operating costs, and reduced compressor motor life.
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A/C and heat pump compressor/condenser installation, location, and maintenance tips provided here include attention to compressor support pads and avoiding air conditioning refrigerant leaks are addressed.
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.
Sketch at left provided courtesy of Carson Dunlop Associates.
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.
Air Conditioning Compressor Location Problems
Inadequate air circulation clearance around an air conditioner compressor/condenser unit
Typical outside air-cooled A/C compressors require a minimal clearance around the unit to provide adequate air flow so that the condenser coils will be cooled efficiently. Both of the air conditioning installations shown above are tipping and the left hand compressor/condenser unit was actually leaning on the house wall!
Air conditioning compressor/condenser units mounted too close to a wall, surrounded by shrubs, or multiple units located too closely together may not receive enough cool air flow to function properly. The result can be a shorter compressor life (expensive) and/or less efficient cooling operation (higher operation costs).
These four air conditioner compressors were found jammed into a wall niche along a street in Queretero, Mexico. These units may have a short life before needing replacement.
Where there simply is not adequate space to provide proper air circulation around an air conditioning compressor or multiple compressors, it may be a good idea to let the building owner know that the units won't have a long life.
Air Conditioner Compressor/Condenser Units Overgrown with Shrubbery
This collection of air conditioning compressors are too many too close together - they will be fighting for cooling air around the condenser unit, increasing operating cost and shortening air conditioner compressor life.
Adding to this scene is the overgrowth of shrubs along the compressor/condenser units. The owner didn't want to see these "ugly" devices but she should have kept the plants trimmed off of the units themselves to allow airflow. The shade was a great idea however, so long as these are just air conditioning units and not heat pumps that want warmth in winter.
One of our clients was "punished" by their air conditioner installer when she said that she didn't want to see or hear the compressor/condenser units, and when she was installing nine of them at her large home. The installer built a rack allowing the units to be stacked on top of one another, three across and three high, with very little air space between.
Then the installer put up a stockade fence just a few inches away from the compressor/condenser units. They were hard to see, it was true, and hard to service. But as the property manager confirmed, they were having to replace several of these units every few years. I believe it was because the units ran excessively hot all the time, lacking adequate air and clearance. Photo withheld for privacy.
Please see our detailed article about refrigerant line piping installation, inspection, defects, repairs, found at REFRIGERANT PIPING INSTALLATION. Excerpts below:
Refrigerant Line Mounting Requirements
Absence of slack in the coolant lines at the compressor units can cause leaks: should the compressor move, perhaps because its supporting pads settle, there will be likely leaks at these lines. You should review this question with your HVAC service person. This item may be deferred until next maintenance or service.
Protection from mechanical damage on all refrigerant lines is important to prevent leaks.
CarsonDunlop Associates' sketch (left) shows the indoor air handler unit, not the outside compressor/condenser unit, but the illustration makes clear that the refrigerant piping loop needs to be properly placed and the piping slope should be downwards from the evaporator unit towards the compressor/condenser unit.
Also, referring lines should not be buried underground. Details are at REFRIGERANT PIPING INSTALLATION.
Refrigerant Line Insulation Requirements
Missing insulation on the refrigerant lines, particularly on the larger suction line, will cause condensation and drips from the lines in humid areas. I've seen very costly building damage where lines were not properly insulated indoors: condensate drips wet gypsum board walls, leading to a costly mold remediation project.
Minimum Clearance Distances from Building Walls, Shrubs, Other Equipment
Blocking air flow through the outdoor A/C or heat pump compressor/condenser unit is a really bad idea that shortens equipment life (as the equipment runs hotter) and increases system operasting costs (for the same reason - hotter opeating temperature means lower efficiency during the cooling season).
Air conditioning or heat pump compressor/condenser units mounted too close to a wall, surrounded by shrubs, or multiple units located too closely together will probably not receive enough cool air flow to function properly.
And even worse, compressor/condenser units that are too close together not only have to fight for their incoming cooling air, but they may veed hot exhaust air to one another, increasing their operating temperatures still further.
Air Conditioning Compressor/Condenser Unit Support Pads - Leveling Requirements for Compressor/Condenser Units
Outside A/C compressors are typically supported on a concrete pad, concrete blocks, or a vinyl pad such as the one shown in the photo at page top. The air conditioner compressor support pad should be level and secure against movement.
Compressors which are badly out of level may fail to function properly and need adjustment. Tipping and moving compressors can also cause can cause leaks in refrigerant lines, leading to costly air conditioning service calls to evacuate and recharge the system after repairing the refrigerant leak.
Do not try to move your A/C compressor yourself as you might cause a refrigerant leak or may otherwise damage the equipment.
Ask your A/C service technician to evaluate the effects of any out-of-level conditions of the compressor as well as to comment on the available slack in the refrigerant lines that may be needed to reposition the unit.
For slightly-tipped air conditioning compressors we generally leave them alone but we add support as needed to avoid further movement.
Tipped or leaning air conditioner compressor/condenser units
Tipping or leaning air conditioner compressors can lead to so much movement that the refrigerant lines crack and leak, leading to loss of cooling ability. In extreme cases, a tipped condenser unit may fail to operate properly. In the first photo above the compressor is leaning and creeping away from the building and has pulled its connecting wiring and refrigerant line taut.
I expect a problem soon with this unit. In the second photo everything looks awful: the two compressors are too close together and too close to the building wall for adequate air circulation, especially in the larger rear unit in the photo. The safety electrical switch for the air conditioner is falling off of the wall, and the rear unit is sliding off of its support pad. This was a poor air conditioning system installation.
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Frequently Asked Questions (FAQs)
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Question: My compressor is out of level
My A/C compressor is out of level just slightly - is that going to make trouble? - Dimc
Dlmc: - requirement to level the air conditioning or heat pump compressor -
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