There are 5 possible reasons your air conditioning and/or heat pump system is not putting out cool air into your house.
Having the thermostat set to a temperature too low in comparison to the outside temperature of the day may be the cause – which is why the thermostat is the first place to check.
The air conditioning unit will not bring down the temperature in your space any faster with a lower thermostat set point than normal, but the air conditioning system will continue to work harder to reach that temperature setting.
Most air conditioning and heat pump systems are designed to provide a cooling range of approximately 15 to 22 degrees difference between the incoming and output air temperatures. So, setting your thermostat at 65 degrees or lower on a 93 degree afternoon would cause the air conditioner to work overtime. This issue is increasingly common on extremely hot and humid days.
Insufficient Air Flow
Another common cause is improper or restricted airflow. To check your airflow ensure that all vents are open in the house and that there is nothing obstructing them, such as furniture or curtains. This applies to both the cooling vents and return air vents.
Problems with the system that impede the air flow are often the below – call your HVAC technician for a service check to address these conditions.
- Dirty filter(s) that are preventing the air from getting to the cooling evaporator coil
- Dirt/Dust/Pet Hair/Debris clogging the evaporator coil
- Dirty or clogged indoor fan blower wheel
- Low fan motor speed
Condenser Not Transferring Heat to the Outside Air
If there is not sufficient air flowing around the condenser coils, the compressor has to work for a longer time with increasing pressures and raising the temperature in order to get the refrigerant to condense back to a liquid.
This may occur in the following circumstances:
- There is something blocking the condenser unit such as plants or shrubs.
- The condenser coils are dirty or clogged, possibly with grass clippings, dirt, leaves, etc.
- The condenser unit fan is not working.
Low or Leaking Refrigerant
If the level of refrigerant in your heat pump or air conditioning unit is not sufficient, it will take longer to cool or not adequately cool.
When this happens, the condensation on the coils can freeze, and reduce or eliminate the air flow that can be in direct contact with the evaporating coil.
Unfortunately, leaking refrigerant may indicate another problem to be repaired which is not properly addressed by merely recharging the refrigerant level back to factory levels. The proper thing to do is:
- Test for the leak and attempt to repair it
- If the leak is slow or not immediately detectable, an injection of dye with the refrigerant can be used to reveal the leak.
- The leak may also be addressed by injecting a sealant along with the refrigerant which can eliminate small leaks.
Leaks typically occur at fittings and connections but sometimes occur as pin-hole leaks in the evaporating coil or the condenser coil. The only adequate repair for leaks in these coils is replacement.
General Poor Performance: Age of the Heat Pump or Air Conditioning Unit
Heat pumps have an average lifespan of around 15 years, with air conditioners lasting roughly 15 – 20 years. As a unit reaches end of life, the system will deliver less efficient and longer cooling cycles. When your unit reaches this point, this will require replacement with an entirely new unit.