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HomeRepair HelpGrandAire Central A/C RepairGrandAire Central air conditioner - home's humidity is too high Repair
GrandAire Central air conditioner - home's humidity is too high
If your GrandAire central air conditioner is leaving the house humid, the most likely cause is a dirty or clogged air filter. Restricted airflow can make the evaporator coil frost over, preventing the system from removing moisture. Replace the GrandAire air filter as recommended, especially if you have pets or a dusty home. Next, check whether the condenser coils are dirty. Debris prevents the coils from releasing heat, so the compressor may run continuously while the air conditioner still cannot dehumidify the home. If the filter and coils are clean, a defective temperature control thermostat may shut the system off too soon, causing an AC not removing humidity problem or a house humid with AC running. A faulty thermistor can also send inaccurate temperature readings to the control board. The control board is less common and should be checked only after these parts. You can safely replace a filter and, with power disconnected, clean accessible coils according to the owner's manual. Electrical testing, 240V components, and any sealed-system or refrigerant repair require a licensed HVAC technician. Enter your GrandAire model number to find the exact replacement air filter, thermostat, thermistor, or control board for your central air conditioner.
01 - GrandAire Central Air Conditioner Air Filter
If the air filter is clogged, air cannot flow properly through the air conditioner. This greatly reduces the cooling capacity of the air conditioner. In addition, if the air filter is clogged, the evaporator coils will frost over. Check and replace the air filter at least twice a year, more often in dusty/dirty environments or if there is a pet in the home.
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Highly Likely
02 - Clogged Air Filter
If the air filter is clogged, air cannot flow properly through the home's venting system. This greatly reduces the cooling capacity of the air conditioner. In addition, if the air filter is clogged, the evaporator coils will frost over and not be able to remove moisture from the air. The air filter should be checked and replaced at least twice a year, more often in dusty/dirty environments. Refer to owner's manual for guidance.
Highly Likely
03 - Condenser Coils are Dirty
The condenser coils dissipate the heat as the refrigerant passes through the coils. If the condenser coils are dirty, they won’t be able to dissipate the heat as effectively. As debris builds up on the coils, the air conditioner will become less efficient, causing the air conditioner to work harder to cool down. If the coils are significantly dirty, the air conditioner will not be able to remove the moisture from the air and maintain the proper temperature, resulting in the compressor running continuously in an attempt to cool the room. Check the condenser coils to determine if they are dirty. Refer to owner's manual for cleaning instructions.
Highly Likely
04 - GrandAire Central Air Conditioner Temperature Control Thermostat
The temperature control thermostat is a sensor which monitors the temperature of the air and activates a switch to provide power to the fan and compressor when the air temperature drops below a set point. If the thermostat isn’t working properly, the air conditioner may not stay running long enough to remove the moisture in the air and cool properly. To determine if the temperature control thermostat is defective, use a multimeter to test it for continuity. If the thermostat does not have continuity, or is shutting off too soon, replace it. (Note: Some thermostats may also control a heater and, as a result, will have three...
Common
05 - GrandAire Central Air Conditioner Thermistor
The thermistor is a sensor connected to the control board that detects the temperature of the air. The resistance value of the thermistor changes in conjunction with the air temperature. If the air temperature rises, the resistance value will decrease. To determine if the thermistor is at fault, use a multimeter to test it for continuity. If the thermistor does not have continuity, or if the resistance of the thermistor does not change with a change in temperature, replace the thermistor. (To find specific temperature and resistance values, try checking your user’s manual.)
Less Common
06 - GrandAire Central Air Conditioner Control Board
The main control board regulates the voltage to the compressor and the fan motor. If the control board fails, some components will not function properly or will not work at all. Control boards are often misdiagnosed; make sure to check more commonly defective parts first before replacing the control board.
Less Common
Frequently Asked Questions
Why is my central air conditioner not removing humidity from my home?
Can a thermostat cause my air conditioner not to dehumidify?
Could a frozen evaporator coil cause high humidity and weak cooling?
How do I test the thermostat or thermistor on a GrandAire central air conditioner?
How do I find the correct GrandAire central air conditioner replacement part?
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