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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
This air conditioning repair article discusses the damaged air conditioner condensing coil fin damage & compressor, including bent or clogged fins which can interfere with effective system operation and improper support such as tipped or leaning A/C compressors.
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Which Cooling or Heat Pump "Coil" is Which: Condensing Coil & Cooling/Evaporator Coils Defined
The CONDENSING COIL discussed here is normally on the outdoor or compressor portion of your air conditioning system. The job of the condensing coil is to cool high temperature refrigerant gas to condense it back to a liquid refrigerant form.
The COOLING COIL or EVAPORATOR COIL is the evaporator coil found inside the air handler, used to cool air blown across it and into the building occupied space. If your concern is with If your equipment is a heat pump these terms can be a bit confusing because in heating mode, your heat pump system's indoor coil is warming, not cooling the air blown across it
Shown at above-left: an outdoor condensing coil with badly damaged cooling fins: If the condensing coil fins are extensively bent and damage, airflow across the coil is impeded, causing the same failures and operating cost issues described above for the compressor too close to the building wall.
When coil fins are sufficiently damaged as to be mostly blocked, the coil is not useable and needs replacement. Minor A/C coil fin damage can be repaired using special "combs" sold for that purpose - ask your air conditioner service technician to look at, evaluate, and repair fin damage.
Nova-Tech International and other companies sell coil fin straightening combs, but if your coil is as horrible as this one it needs replacement.
Condensing coils may also become blocked by dirt and debris, interfering with system cooling operation. There is a big payoff in cleaning dust, debris, grass clippings off of a dirty refrigeration condensing coil (this includes outdoor condenser/compressor units for air conditioners and heat pumps and also the condensing coil on a home refrigerator or freezer). A refrigeration system works by transferring heat from hot refrigeration gas/liquid to ambient air around the condensing coil. Remember that heat always flows from the warmer to the cooler substance.
A blocked condensing coil, regardless of the cause of blockage, can also cause the occurrence of refrigerant gas bubbles in the refrigerant piping system - a condition you might hear or see. See details at Bubbles seen or heard in the liquid refrigerant line?
Overheating, Blocked Coils May Cause Air Conditioner or Heat Pump Noise
Because dirt and debris block airflow across the coil, increasing the cost of heating or cooling the building and perhaps even overheating the compressor motor, it is important to keep leaves and debris off of this component. In severe cases cooling or condensing coils can become so blocked that air flow is seriously reduced, possibly also leading to an evaporator or cooling coil icing problem indoors or an overheated, damaged compressor outdoors, or simply loss of cooling capacity of the system.
We first mentioned at NOISES, COMPRESSOR CONDENSER that we had a field report from a reader who explained that a noisy outdoor compressor unit was, according to his HVAC service technician, traced to a blocked, clogged outdoor condensing coil. We speculate that perhaps the compressor was running hot and that correcting air flow across the condensing coil corrected that condition.
Corrosion on Heating & Air Conditioning Heat Exchanger Coils & Condenser Coils
Corrosion on heat exchanging coils in heat pumps, air conditioners, or water-to-air heating coils eventually leads to leaks and costly repairs that require replacement of the coil and re-charging of the HVAC system refrigerant. Corrosion may occur as a function of age and use and failure to keep the coil clean, but there are some special sources of corrosion in HVAC systems that you should watch for:
Types of Air Conditioner, Heat Pump, & Refrigeration System Condensers / Condenser Coils
Above we have explained the purpose and function of condensing coils and condensers used in air conditioners, heat pumps, and other refrigeration equipment such as dehumidifiers, refrigerators, and freezers. Here is more detail about the types of condensers and condensing coils and where they are used.
Static condensers rely on the natural movement of air across the condensing coil (such as in many residential refrigerators and freezers). For a static condenser to work you must leave air space on both sides and above the condensing coil to allow for airflow by natural convection (as no fans are used).
Oil cooler condensers are a type of static condenser that use two or three turns of tubing to cool oil that is then sent back into the compressor motor in a repeated cycle. These condenser (cooling) coils found on some compressors (commercial) also must have adequate airlfow.
Static condensers may also be found in a split in the compressor motor shell, between an inner and outer box shell - such as used in halo heaters - to reduce air condensation. You can identify a split shell or box shell static condenser because the box is warmer on the outside sides and at the compressor motor top than at the bottom. These static condensers also require airspace for natural air convection.
Forced air condensers require a fan to move air across the condensers' cooling fins and coils. On an air conditioner or heat pump compressor/condenser unit the fan typically draws outdoor air through the coil and out an exhaust side of the condenser unit. When used on a residential refrigerator or freezer the condenser coil may be at the bottom (or in some designs the top) of the unit where a fan blows air across the condensing coil and out of the box again.
Clean the refrigerator coils? In an expert witness court case involving a matrimonial dispute we [DF] testified that a refrigerator had overheated, burning the vinyl flooring in the kitchen when the condensing coils had been left plugged with animal hair and dust. One of the attorneys asked if it was our opinion that refusing to clean the coils had been a deliberate act of sabotage on the part of the building occupants. "Of course not," I answered, "most people never clean their refrigerator or freezer coils - they never think about it until the equipment fails."
Pets like to lie close to a bottom-mounted condenser coil/fan unit at refrigerators and freezers, to enjoy that nice warm exhaust air in cool weather. A result is a coil clogged with pet hair that needs more frequent cleaning. Even if it doesn't burn the floor under you refrigerator, a dirty condensing coil means a less efficient refrigerator or freezer operation and higher electrical bills.
Reinstall the airflow panels that you might remove to clean a refrigerator or freezer condenser coil. Failing to do so means air will no longer pass properly over the condensing coil. The result, as with pets, is a higher electrical bill.
Changing Out or Replacing a Bad Condenser Coil on an Air Conditioner or Heat Pump
Reader Question: what is the cost will be to replace the A/C coil and refrigerant gas
3/26/14 chuck said: My condenser coil has failed and all Freon has leaked out. Any idea of what the cost will be to replace the coil and Freon?
Chuck, in a companion article on refrigerant leaks at REFRIGERANT LEAK REPAIR we comment on coil repair options.
The actual repair cost range is quite large, ranging from a DIY epoxy kit to a service call to a coil replacement to a complete HVAC system replacement, depending on the cause of the leak, the refrigerant type or age of the system, and thus the repair options.
To replace an AC condensing coil you could be looking at $1300 - $1500. U.S.D. vs. $2000 to $3000 to replace the whole unit.
See ADDING A/C: RETROFIT SIZING for an example of a mismatch that means poor heating or heat pump system operation.
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.
As we also cite in our information about the COOLING COIL or EVAPORATOR COIL, a condensing coil can also need replacement due to damage, leaks, or corrosion. When replacing a condensing coil it is important to match the size of the original coil so that the air conditioner, heat pump, or other equipment remains properly balanced among compressor, condenser, and evaporator.
Condenser coil piping and tubing is smaller diameter than the suction lines, and are often made of steel. Keep in mind that when soldering steel to copper refrigerant piping you'll need to use silver solder or brazing.
See details about HVAC piping soldering discussed at REFRIGERANT PIPING INSTALLATION
More details about proper comprssor/condenser unit installation and placement are at INSTALLATION ERRORS, COMPRESSORS.
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