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FAQ on Air Conditioning - Part II: Performance and Troubleshooting

Filan & Conner provides emergency air conditioning service all over West Berlin and neighboring cities. As mentioned in Part I of this FAQ, homeowners ask our technicians many good questions about AC that call for reliable, educated answers.


Air conditioners are a big investment in a home, and keeping your AC operating at manufacturer’s specifications will not only prolong its lifespan, but also help capping your energy bills.


This Part II of our FAQ addresses the issue of performance and gives you pointers as to what could be wrong with the unit in case it starts malfunctioning.


IMPORTANT: This FAQ is not a diagnostic manual however, and we just publish it for informational purposes. Because your manufacturer’s warranty almost certainly requires a professional AC technician to do regular maintenance on your unit, we recommend that you follow th terms of your warranty.


Why is my air conditioner not cooling properly?


Short Answer:

There are several reasons why your air conditioner might not be cooling properly. Amongst them, some of the most common are dirty filters, low refrigerant levels, and a malfunctioning thermostat.


Check your filters regularly and replace or clean them as needed. If the problem persists, it is best to consult with a professional AC technician to diagnose and fix the issue.


Technical Answer:

When an air conditioning unit does not cool off properly, we systematically suspect 3 potential issues:


(1) The air filters are clogged and the airflow is restricted. The system has to work harder to circulate the same volume of air;


(2) A system may be low in refrigerant due to leaks in the refrigerant lines. This problem typically occurs at the fittings and connectors, but it can also be the result of a puncture in the copper lines;


(3) The evaporator and condenser coils are dirty, and the dirt impedes the cooling process.


These are not all the reasons: a malfunctioning thermostat, electrical issues, or a compromised compressor can also be culprits.


Each part of the system needs to be diagnosed to detect abnormalities and excessive wear and tear. Regular maintenance and timely interventions will tend to prevent these issues and ensure consistent cooling performance.


Why is my AC blowing warm air?


Short Answer:

If your AC is blowing warm air, you could be facing a tripped circuit breaker, low refrigerant levels, or a dirty evaporator coil. You could start your diagnostic by setting the thermostat to "cool" and checking the circuit breaker. If the issue persists, seek the assistance of a professional AC technician.


Technical Answer:

An AC blowing warm air can be due to multiple technical issues. The easiest to address is the tripped circuit breaker: set your thermostat to "cool" and the temperature below your current room temperature. If the unit doesn’t start quickly, check your electrical panel for a tripped circuit breaker.


You can also check your filters and the return vents. Dirty filters, or blocked return vents will prevent air from circulating normally and your AC won’t cool off your home normally.


As mentioned elsewhere in this FAQ, the issue could be related to low refrigerant levels. That’s not a repair you can do yourself without risks, even if you have the gauge to measure the pressure in the system.


When there is a leak in the line, only a professional AC technician will know how to fix it properly. Don’t try to fix this yourself.


Another cause hindering the cooling process is a dirty or frozen evap coil. Again, this is one type of failure point that calls for a professional intervention.


As best practice, we recommending getting your AC inspected twice a year (spring and fall) to prevent these issues.


If the issue occurs, don’t delay calling an AC technician: the longer your AC has to work with the root cause of the issue, the more likely it will experience a catastrophic failure.

Why is my AC constantly running?


Short Answer:

If your AC is constantly running, it might be undersized for the space it is cooling at the current temperature levels. It may also have a thermostat issue. Dirty coils or clogged filters may be reducing its efficiency. If you see no improvement after adjusting your thermostat, consult a professional technician.


Technical Answer:

An AC that is continuously running can be an indication of several technical inefficiencies.


One of the more common ones during a hot summer is the unit is undersized for the volume of air it tries to cool off. The unit may be operating normally during the rest of the year, or even in regular summers.


But during a heat wave like we have seen in recent years in New Jersey, the same unit just struggles to cool off the volume of air in your home because the temperature outside is too warm and your insulation not efficient enough.


Another relatively simple issue may be a thermostat malfunction: old thermostats, especially mercury-based models, can cause your system to run continuously.


Diving deeper in the diagnosis, we would examine the state of your condenser and evaporator coils, and the level of refrigerant in the lines looking for potential leaks as applicable.


Why is my AC freezing up?


Short Answer:

Your AC might freeze up due to restricted airflow, low refrigerant levels, or a malfunctioning blower motor. Check the filters and replace them if dirty. If the problem persists, it is best to contact a professional AC technician.


Technical Answer:

There are several technical factors at the root of an AC unit freezing up.


Restricted airflow, often due to a dirty filter or blocked return vents, can cause the evap coil to freeze.


Low refrigerant levels, typically resulting from leaks, will reduce the pressure in the system, leading to freezing. A malfunctioning blower motor does not allow the air to circulate effectively, causing the coils to freeze.


Typically, homeowners don’t know that the coils of the system are frozen. When a professional AC technician detects that this is the origin of the problem, they will address it immediately because it could lead to compressor damage, a very costly repair.


Why is my AC turning on and off frequently?


Short Answer:

If your AC is turning on and off frequently, it might be "short cycling." This can be due to an oversized unit, a dirty evaporator coil, or some electrical issues. Address this promptly by calling a professional AC repair technician, as the situation will increase wear and tear on the system.


Technical Answer:

"Short cycling" is a technical term used to designate a situation when an AC turns on and off frequently. This can be due to several reasons.


An oversized AC unit, for instance, will cool down a home quickly and then shut off, only to restart shortly after.


A dirty evaporator coil or a clogged filter will cause an AC unit to overheat and shut down prematurely.


Electrical issues (faulty relays or capacitors) can also lead to short cycling.


Sometimes, the thermostat sensor is bad, and gives false temperature indications to the system.


Short cycling will increase wear and tear, because the spike of current that occurs when the unit fires up will progressively deteriorate the electronics and reduce the lifespan of the system.


Newer AC system will have variable speed motors, which stay “on” all the time but slow down when ideal temperature is reached. They don’t start-and-stop like the other motors.


Why is my thermostat not reaching the set temperature?


Short Answer:

If your thermostat isn't reaching the set temperature, it could be due to an incorrect calibration, a malfunctioning sensor, or issues with the AC unit itself. All these issues must be looked at by a professional.


Technical Answer:

A thermostat not reaching the set temperature can be a complex issue with various technical underpinnings. Incorrect calibration can cause discrepancies between the set temperature and the actual room temperature. Malfunctioning sensors can relay incorrect temperatures, causing the system to underperform.


The location of the thermostat also plays a role: if placed near heat sources or in direct sunlight, it would typically register higher temperatures.


In one case, we found that a thermostat had been relocated to close to a kitchen stove, causing it to read abnormally high temperatures. Repositioning the thermostat elsewhere solved the issue.


It is also possible that the AC unit itself is undersized or has some malfunction and can’t achieve the desired temperature.


Why is there ice on my AC unit?


Short Answer:

Ice on your AC unit can result from restricted airflow, low refrigerant levels, or a malfunctioning blower motor. Ensure the filters are clean and the vents are unblocked. If the icing continues, consult an AC repair technician.


Technical Answer:

Technically, ice formation on an AC unit is indicative of operational inefficiencies.


Restricted airflow, often due to dirty filters or blocked vents, can cause the evaporator coil temperature to drop below freezing, leading to ice formation.


Low refrigerant levels, typically due to leaks, can cause the coil to freeze. A malfunctioning blower motor would not circulate air effectively, leading to freezing.


Along our service history, we found more than once that the AC units had a kinked refrigerant line: this caused reduced flow and subsequent freezing. Rectifying the line and recharging the refrigerant resolved these issues.


Whenever you find ice on your AC, cal a technician to address the issue promptly, as continuous freezing will damage your compressor, a costly repair.


Why is my indoor unit running but not the outdoor unit?


Short Answer:

If the indoor unit is running but not the outdoor unit, that could be due to a tripped circuit breaker, a faulty capacitor, or electrical issues. You can check the circuit breaker yourself, and reset if necessary.


If the tripping problem persists, you need a professional AC repair technician electrician to look at the circuit.


It may also be necessary to call a professional electrician if the issue is not with the AC unit itself. If the issue is not the circuit breaker and the outdoor not is not kicking in, call a professional AC repair company.


Technical Answer:

From a technical standpoint, the dis junction between the indoor and outdoor units operation can be due to various reasons.


The outdoor unit might be disconnected from power due to a tripped circuit breaker or a blown fuse. This should be easy to fix.


If the breaker continues to trip, it’s an indication something is wrong in the electrical system or at the AC level.


Faulty capacitors can prevent the compressor and the fan in the outdoor unit from starting.


Electrical issues, such as damaged wires or malfunctioning relays, can also be culprits. Chewed wires are a common occurrence in the rural parts of New Jersey. Once the wiring is fixed, you need a pest control technician to come and fix the rodent issue.

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