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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
How to diagnose an air conditioner or heat pump that is not cooling: this article explains how to diagnose and correct air conditioning problems like lost or reduced air conditioner cooling capacity, reduced or no cool air flow, reduced or no actual lowering of the air temperaturer, or an air conditioner that won't start. If not enough cool air is provided by your air conditioner, or if the air temperature is not cool enough, or if you just can't get your A/C unit running, this article helps diagnose and correct the problem with step by step things to check and links to more detailed explanation when you need it.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
These Simple Checks May Enable Inexpensive Repair of Lost Cooling Output from an Air Conditioner
If you don't see information you want, ask us for it using the comments box on this page. If your air conditioner or heat pump is a split system or mini split system design (using a wall-mounted cooling or heating unit) our troubleshooting diagnostics are at SPLIT SYSTEM AIR CONDITIONERS & HEAT PUMPS.
Is there no cool air at all coming out of the supply registers?
Or is there air blowing out of the supply registers but it's not cool enough?
Here we explain how to diagnose loss of air conditioning cool air flow or cool air temperature.
Before ordering an expensive air conditioner service call to restore lost cooling capacity, here are a few simple steps to perform. Some of these can be done by any homeowner, others may require a bit more expertise.
Below we provide first a very basic Air Conditioning or Heat Pump Diagnostic Checklist, followed by more detailed descriptions of common problem cooling system topics.
First try our air conditioner checklist just below - try these steps before calling your HVAC service company.
Following the checklist we provide more detailed descriptions, photos, and links to in-depth air conditioning inspection, diagnosis, and repair or improvement advice.
Where to start: check that the air conditioning equipment is turned on, the thermostat is calling for cooling, and that the blower unit or air handler is actually blowing air through the ductwork. Details of how to proceed in figuring out what's wrong with your air conditioner begin just below.
If the air conditioning system is not running at all:
If the air conditioning system is still not working, or if the A/C system is running but cool air is not coming out of the supply registers you probably need to call a service technician, but below are some things to check further yourself.
If At Least Some of the Air Conditioner or Heat Pump Equipment is Running but Cool Air is Not Being Delivered -
If you cannot find your air conditioner controls and switches see A/C - HEAT PUMP CONTROLS & SWITCHES - list of controls and switches found on air conditioners and heat pumps
Also check the compressor/condenser outdoor fan and fan motor
Condensing unit fan diagnostics: at FAN, COMPRESSOR/CONDENSER UNIT we explain the diagnosis of problems with the compressor/condenser fan and fan motor.
Also see ELECTRIC MOTOR DIAGNOSTIC GUIDE.
At BURNED-OUT COMPRESSOR we explain that if the condensing unit fan is not working the compressor itself may shut down or even be ruined by overpressure or over temperature. Also see NOISES, COMPRESSOR CONDENSER where some noise problems are traced to the cooling fan .
Is the indoor blower unit running? If not be sure that the electrical power switch at your furnace or air conditioner air-handler is in the "on" position. Typically the air handler or blower unit is indoors inside the basement, crawl area, or attic.
Also see ELECTRIC MOTOR DIAGNOSTIC GUIDE.
If your air conditioning equipment is running but little or no cool air is coming out of the supply registers, check that your air filter(s) have not become blocked with dirt and debris.
See A/C Filter Problems for details
In ceilings, walls, or floors, where cool air is supposed to be delivered to various rooms in the building, be sure that the register is in the "open" position (you will be able to see through it into the ductwork) and be sure you haven't blocked the supply registers with a carpet or furniture.
Look for a duct damper or register that has been closed; look for a flex-duct section that has become disconnected, bent, or crimped or squashed. Remember that a duct may have become disconnected in an attic or crawl space.
Look for an air filter that has come loose and blown into the ductwork, clogging it.
At left you can see a ceiling air supply register that has leak stains around its opening - further investigation for a condensate leak or roof leak is needed.
If the indoor air handler blower fan itself won't start, see BLOWER FAN OPERATION & TESTING. Check for lost power, a fan motor that wont' start or has tripped a motor reset button or needs a start / run capacitor. Check for a blower fan that is loose on the motor drive shaft or for a broken or lost blower fan drive belt on pulley-driven blower systems.
Also see ELECTRIC MOTOR DIAGNOSTIC GUIDE for details
Air Conditioner Blower fan unit not moving enough air: too little air coming out of your air conditioning ducts?
Air flow that is too slow for any reason (such as a dirty filter or dirty blower fan assembly blades) can cause first, air temperatures that are abnormally low coming out of the air conditioner, and eventually a reduction in air flow as coil ices over. See A/C Cooling Coil Icing.
Air flow that is too fast for any reason (improper fan motor, speed, fan belt or pulley size, duct design, duct registers removed, etc) can produce air that is not cool enough and can prevent proper air dehumidification (oversized A/C system). A/C Not Dehumidifying.
Check and Fix These Existing Air Conditioning Problems Before Trying to Improve its Cooling Capacity
Watch out: It could be a mistake to spend on any costly air conditioning improvement if the original system actually already had the needed capacity, but simply needed maintenance (like replacing a filter - A/C Filter Problems) or repair (like repairing a leaky duct - A/C Air Duct Problems).
FIRST: review all of the air conditioning performance diagnosis suggestions here at - LOST COOLING CAPACITY to be sure there is not something that needs to be repaired or corrected with the system. For example we have seen cool air output significantly improved by finding and fixing a disconnected cool air duct that no one had noticed in a hard-to-access crawl area.
Certainly some central air conditioning systems, especially retrofit designs, have less than optimum duct design, such as inadequate central return air registers, room doors that are so tight that it is difficult to blow cool air into the room when the door is closed, inadequate supply ducts or less than optimum supply register placement such as only in floors. But redesigning and installing for an optimum air conditioning duct system can be costly, so it might be worth taking some other steps.
SECOND: make sure that other energy-savings steps have been taken in the building, such as proper insulation, sealing un-wanted drafts, etc. See ENERGY SAVINGS in buildings - those suggestions apply to both heating and cooling costs.
If your HVAC service technician is sure that the present cooling system is working as intended, then if you are not considering supply or return air duct improvements, or a replacement air conditioner system of higher capacity, you might consider a stronger blower fan (discuss what you could do with your HVAC tech), or booster fans individual registers.
Watch out - just boosting air conditioner air flow by installing a higher capacity blower fan is not that simple - if the blower moves air through the duct system faster than the design speed for the system ,the cooling coil may be insufficient in capacity, the air will not be dehumidified (and the building will be less comfortable - A/C Not Dehumidifying), or you might get annoying duct or equipment noises. Discuss these possibilities with your HVAC service company.
Clogged Air Conditioner filters can lead to lost cooling capacity first, because the clogged filter reduces the air flow
through the system, meaning that you'll feel less air flow at the supply registers than was previously present.
Compressor problems - Air Conditioner Compressor: problems such as an aging air conditioner compressor motor that is at or near the end of its life may be unable to
properly compress the returning refrigerant gas to a sufficiently high pressure. A service technician will need to evaluate and test the system
and if needed, replace the compressor.
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.
Air conditioner compressor problems, including compressor noises, hard starting, and burned-out compressors, are explained in detail beginning at COMPRESSOR & CONDENSING COIL and includes topics such as BURNED-OUT COMPRESSOR and MOTOR OVERLOAD RESET SWITCH.
A compressor which appears to have lost cooling capacity can be diagnosed by a service technician who can connect the appropriate test gauges to the system. Lower than normal discharge pressure and higher than normal suction vacuum will indicate this problem.
But before assuming that something is wrong with the air conditioning compressor, some basic investigation is in order. Unless there is an obvious indication of a compressor problem (noise, hard starting, compressor won't start), the service technician, to be thorough and economical, will inspect the system in an order, checking the easy and least-costly problems first, such as presence of electrical power, proper setting and operation of system controls, condition of filters, condition of duct work, operation of blower fans, before moving on to check the compressor itself by looking at the air conditioner operating temperatures, pressures, and current draw in Amps.
The cooling capacity of an air conditioning equipment refers to the ability of the compressor/condenser (usually outside) and the air handler/evaporator (usually inside) to deliver cool air to the occupied space.
Briefly, the compressor/condenser draws refrigerant gas from the building air handler, compresses it and cools it back to a liquid refrigerant, and the air handler/evaporator coil permits liquid refrigerant to evaporate inside a cooling coil, across which the fan blows building air to cool and dehumidify it.
The particular combination of this equipment has a cooling capacity, usually rated in BTUh or thousands of BTU's of cooling capacity per hour, documented on equipment data tags discussed at RATED COOLING CAPACITY.
Also see COOLING RULES OF THUMB to guesstimate how many tons or BTUs of cooling a building needs and see RATED COOLING CAPACITY to determine the cooling capacity of existing air conditioning equipment.
A longer than normal on cycle combined with little or no cool air conditioner output could be due to an inefficient air conditioning compressor or one which has lost its ability to "compress" the refrigerant due to internal wear. This condition can be diagnosed by an air conditioning service technician who will install air conditioning manifold gauges onto the system to check the compressor suction vacuum and discharge or "high side" output pressure. If gauge ports are not installed on the air conditioner compressor unit the technician cannot make this test without cutting the refrigerant lines to install gauge ports (adding to the cost of this diagnosis).
Low amperage draw: unlike a high-amp current draw which indicates that the compressor is danged internally in a way that its piston(s) is(are) tight in the cylinder, a low-amp current draw, if below normal, may confirm internal wear on the compressor parts, and would support the diagnosis that the compressor is worn and inefficient. Where there are no gauge ports to actually measure compressor low side and high side vacuum and pressure, this simple electrical test is a useful first step.
See ELECTRIC MOTOR DIAGNOSTIC GUIDE for how-to details.
If you have the opposite concern, that is the A/C compressor is turning on and off too frequently, see SHORT CYCLING AC COMPRESSOR.
Refrigerant line pressure readings which are abnormal (probably too low) on the high pressure side (compressor output) or on the low pressure side (compressor input or suction line) can indicate a problem with the compressor's ability to develop normal operating pressure ranges and thus will affect the cooling capacity of the air conditioning system. For more details on air conditioner refrigerant line pressures and how they are examined see COMPRESSOR PRESSURE READINGS
Details about air conditioning compressor functions, how air conditioner compressors work, what goes wrong with air conditioner compressors, and how to measure and diagnose air conditioner compressors are provided at COMPRESSOR CONDENSER.
Several readers have described a step of cooling down an overheated air conditioning or heat pump compressor motor to get it running again producing cool air indoors. One reader used a garden hose to spray the outdoor unit (after all it's intended to tolerate being rained-on). Another used a watering can. A third, buckets of water.
All three reported that this step got their cooling system cooling again when before either the compressor had stopped running entirely or it was running but the system was not producing cool air. But for several reasons this is not an effective durable repair:
While we wait for more comments from air conditioning service technicians and experts (CONTACT us), here are some interpretations of what may be going on:
Cooling Coil Ice-Up on the air conditioner air handler or evaporator coil: A second result of the reduced air flow due to a dirty air conditioning filter can cause
the evaporator coil (the cooling coil) in the
air handler to become blocked by ice, stopping or significantly reducing cool air output from the system.
Cooling Coil (Evaporator Coil) Leaks, Condensing Coil Leaks: if your A/C system used to work fine but now is blowing only warm air, it is possible that you have lost refrigerant in the system. A refrigerant leak can occur anywhere in the refrigerant piping system, in the cooling coil, or in the condensing coil.
You'll need an HVAC technician to find and repair the leak problem. If the leak is in a refrigerant line it can usually be soldered and sealed and the system re-charged. If the leak is in a cooling coil or condensing coil, the coil probably needs to be replaced. We explain this topic in more detail below at Air Conditioner Refrigerant Problems - Refrigerant Leaks, Low Refrigerant, Wrong Temperatures.
Details about inadequate dehumidification by central air conditioning and heat pump systems are found at DEHUMIDIFICATION PROBLEMS. Excerpts are below.
Air Conditioning Dehumidification Problems: air conditioning system cools but does not dehumidify the room. The most common cause of inadequate dehumidification by an air conditioning system is the installation of a cooling unit which has too much capacity, or is "over-sized" for the space it is being used to cool. What happens is simple:
"Bigger" cooling capacity or higher BTU capacity for an air conditioning system is not necessarily better, and it can actually prevent the air conditioner from adequately dehumidifying indoor air.
Sketch courtesy of Carson Dunlop Associates.
See details about indoor dehumidification problem diagnosis and repair at DEHUMIDIFICATION PROBLEMS
We discuss the air conditioning system sizing problem at AIR CONDITIONER BTU CHART and while details are found at DEHUMIDIFICATION PROBLEMS, we also introduce the oversized air conditioner problem at LOST COOLING CAPACITY.
Also see COOLING RULES OF THUMB to guesstimate how many tons or BTUs of cooling a building needs and see RATED COOLING CAPACITY to determine the cooling capacity of existing air conditioning equipment.
Even if a very high BTUH capacity cooling system is installed, if the duct system is defective the ability of the system to deliver cool air to the occupied space can be severely or even totally lost.
Duct System Efficiency (in percent) describes the percent of cooled air produced by the A/C equipment which is actually delivered to the occupied space. This number is less than 100% because of air flow restrictions and losses in the duct work.
Duct Delivery Effectiveness is the percent of cooling capacity which is delivered through the registers into the occupied space. Registers themselves restrict air flow. See DUCT SYSTEM & DUCT DEFECTS - see links at left.
So the ability of the entire A/C system to cool a building or rooms in it requires that both the cooling equipment and the duct system be in proper working order.
Details about duct system and air handler diagnosis, including duct defects, air filter defects, and air handler problems are provided at AIR HANDLER UNIT: problems with the air handler, air filters, and the cooling coil itself.
See our complete list of air conditioning system diagnostic and repair guide articles just below.
Sketch courtesy of Carson Dunlop Associates.
Since the failure of an air conditioner to turn on, loss of air conditioner cooling capacity, reduced air conditioning output temperatures, loss of cool air supply, or even loss of air flow entirely can be due to a variety of problems with one or more components of an air conditioner or air conditioning system, after reviewing the lost air conditioner cooling diagnosis procedures described in this article, be sure to also review the diagnostic procedures at each of the individual air conditioning diagnosis and repair major topics listed just below. To return to our air conditioning and refrigeration home page go to AIR CONDITIONING & HEAT PUMP SYSTEMS.
If your air conditioning or heat pump system has lost its cooling capacity or won't start select one or more of the diagnostic articles listed below.
As we stated earlier, check that electricity is on for the equipment, everywhere. Check all switches and controls, including service switches, including outside by the compressor, inside at the air handler, and fuses or circuit breakers in the electrical panel.
For example, condensate spilling into an overflow pan that uses a sensor switch can be enough to shut down your air conditioner. There are several switches and controls, both manual and automatic that can leave an air conditioner or heat pump turned "off" such as a blower compartment door interlock safety switch, an electric motor overload or overheat switches, and a condensate tray spillage detector switch
See A/C - HEAT PUMP CONTROLS & SWITCHES to be sure you have found and checked every manual or automatic electrical switch on the system. A bad or failed starter capacitor could also be leaving your system shut down, failing to start a blower, fan, or compressor motor.
Electrical problems: air conditioning system won't start: it may sound silly, but is the air conditioner turned on?
Air conditioner compressor problems, including compressor noises, hard starting, and burned-out compressors, are explained in detail beginning at COMPRESSOR & CONDENSING COIL and including topics such as BURNED-OUT COMPRESSOR and HARD STARTING COMPRESSOR MOTORS and MOTOR OVERLOAD RESET SWITCH and ELECTRIC MOTOR DIAGNOSTIC GUIDE.
Condensate pan switch lockout: an attic or other air conditioner air handler condensate drip tray or drip pan located under an air handler is installed to catch air handler condensate leaks if the normal condensate drain system fails. Some condensate pans have their own separate overflow drain (a proper installation) or share their drain with the normal condensate drain (an improper installation).
Condensate leaks into the condensate pan can shut down the air conditioner.
So if your air conditioning system seems to be normal in all other respects but it simply won't turn on, check for a flooded condensate pan or a defective condensate switch. See DRIP TRAY DEFECTS and also Use of float switches on air conditioning condensate overflow pans. Also see CONDENSATE DRAIN CLEAN & DE-CLOG and CONDENSATE TRAY CLEANING.
Thermostat problems: Air Conditioner Thermostats:
Air conditioner won't turn on, or fan won't turn on or won't turn off.
Air Conditioner Air Handler Blower motor Won't Start?
See MOTOR OVERLOAD RESET SWITCH just to be sure that the air handler blower fan motor has not shut off on thermal overload. And if your blower fan is driven by a fan belt and an electric motor, of course check to see that the drive belt is in place and un-damaged. If the blower fan belt is broken the electric motor will run just fine (you may be able to hear it) but the blower fan assembly itself won't be turning.
Refrigerant problems: Improper air conditioner refrigerant charge - too little, too much, too leaky: an air conditioner system which has lost some (but not most) of its refrigerant
will sometimes run too cold at the evaporator coil, leading to coil icing and loss of cool air delivery in the home.
Carla said: My outside air unit will not turn off on its own. I have to manually turn the breaker off to turn it off. Does anyone know why or how I can fix it?
Carla if your A/C won't turn off it could be that the thermostat is set to a temperature that the system cannot reach - due to lost cooling or due to a setting below the capability of the system. If your A/C won't turn off even if you set the thermostat to a temperature that is above the current room temp, then the thermostat or an A/C control board or switch is bad and needs replacement - in that case you need a service call from a trained HVAC Technician. See OPERATING TEMPERATURES and also CONTROLS & SWITCHES, A/C - HEAT PUMP
Joe said: short cycling air conditioner compressor diagnosis: I have the same problem as Mathew: my A/C compressor cycles on and of every ~10 seconds. I is about 5yr old. What can we do to fix this system. Please help. Thanks!
Matthew said: short cycling air conditioner problems: Our air conditioning compressor cycles on and of every few seconds or minutes. What can we do to fix this systems not even a year old
DanJoeFriedman (mod) said to Joe and Matthew (re questions just above):
But if someone is turning the system on and off quickly, the compressor may have a hard time re-starting against the pressure on its outlet side. A starter capacitor addition or replacement might fix the problem. If your A/C compressor is showing this symptom but works OK if you leave it shut off for 30 minutes or longer, that may be the trouble.
We have also see or a damaged compressor internal refrigerant valve causing high head pressures;
In sum, you need a service call from a professional to correctly diagnose and repair the problem. Ask the service tech what she/he found and let us know - what you find will help other readers.
If your air conditioner or heat pump has the opposite problem, staying on too long, see LONG-ON CYCLING AC COMPRESSOR.
A/C not producing enough cool air - I had my air conditioning system gassed up last week - $210. ! The unit is not producing enough cold air. The unit is set on 72 and does great at nights but during the day where the temp. outside is reaching mid 90"s it's getting up to 80 in the house. Is my duct work screwed up? How do you repair trailer metal ducting? - Amanda
90 degrees outside and 83 inside with thermometer at 76. Cools off to 76 when sun starts to go down and house then gets cold. New capacitor and condensor just put in. Help. - Ginny 5/17/12
Amanda: if your system is not cooling there could be any of a number of problems - see the article above as a place to start. If your basic complaint is that the A/C temperature at the supply registers is cool enough but the volume of air flow is too weak, we'd start by:
Les said: Weak air conditioner air flow: Our A/C was serviced two months ago and the repairman said it had a leak. $400 later it was recharged with coolant and now the ac is doing the same thing. Very little pressure coming out of vents and no cold air coming out. Does anyone know what I can do for the weekend? It is stifling!!!! See A/C Air Duct Problems
DanJoeFriedman (mod) said:
Les: A leak that was fixed by a re-charge is not as good a repair as a leak that was fixed by finding and fixing the leak - you'll just have to keep adding refrigerant.
But weak air flow out of the vents would not be due to a refrigerant leak; more likely a clogged filter or crushed or disconnected ductwork, or a blower fan problem.
(May 13, 2011) Jim said: If air conditioner filters are clogged will it cause the thermostat to shut off?
Jim: clogged A/C filters won't cause a room thermostat to shut off. The thermostat responds to room temperature. However clogged A/C filters that reduce air flow, cause coil frosting, or otherwise reduce or stop the flow of cool air into the room where the thermostat is located would mean that the thermostat would remain "un-satisfied" and should mean that the thermostat says "on" - continuing to call for cooling. See AIR FILTERS for HVAC SYSTEMS
Question: got one for you. i put an ammeter on my air handler and it read 8.25 amps, I removed the filters and it went up to 9.75 lmao at the situation the amperage should have gone down. what gives here
Lost: this amps variation is beyond my expertise, but in general reducing the load on an electric motor will show up as lower amps or current draw, not higher amps. Here are two interesting explanations of amps or current variations on an electric motor that I found when researching the question:
1. Voltage variations and current draw at electric motors: If your supply voltage is varying from your power company that can show up as higher amps draw on the motor (though it's a suspicious coincidence to see it exactly when you removed the filters and supposedly reduced the load on the motor). Quoting from motorsanddrives [dot] com: "The effect of low voltage on electric motors is pretty widely known and ... The amount of power the motor draws is roughly related to the voltage times current (amps). Thus, when voltage gets low, the current must get higher to provide the same ... To summarize the situation, low voltage can cause high currents"
2. Load variations and electric motor efficiency: A second possible source of seeing higher amps or current draw on your blower motor when you pulled out the air filters and thus reduced the load on the blower motor might be illuminated by this U.S. DOE pamphlet "Determining Electric Motor Load and Efficiency" - Quoting: "Most electric motors are designed to run at 50% to 100% of rated load. Maximum efficiency is usually near 75% of rated load. Thus, a 10-horsepower (hp) motor has an acceptable load range of 5 to 10 hp; peak efficiency is at 7.5 hp. A motor’s efficiency tends to decrease dramatically below about 50% load."
JMONTE said: warm A/C suction line question: After my condenser is turned on for about 4 minutes the suction line starts to get warm to the touch. can you tell me what the problem may be
JMONTE: If the HVAC suction line gets warm, you may be out of refrigerant, or the system may be running in heating mode if it's a heat pump. See OPERATING TEMPERATURES.
Becky, If a motorized HVAC zone control damper is not opening or closing, most likely the motor has failed, or the thermostat that operates that zone control is off or set in an incorrect position. See ZONE DAMPER CONTROLS
Becky said: motorized air conditioning zone dampers not working
My house has "zone" control with dampeners to close off the upstairs over the garage room unless that thermostat is on - the room is not cooling. I have located the damper under the house. What are some causes for the damper not opening and how to repair them? condensation, motor to damper? silicon glued properly?
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