Although thermal expansion valves have been around for decades, many 13 and 14 SEER air conditioners and heat pump systems still use a fixed orifice metering device. A thermal expansion valve can be adjusted depending on the load which makes for a more reliable and efficient HVAC system. They also do a better job that a fixed orifice in the event the system is not charged properly. If your TXV has failed, your air conditioner or heat pump may struggle to reach the set-point on the thermostat. Frost an the indoor or evaporator coil is another sign that a TXV has failed. If the thermal expansion valve has failed on your air conditioner or heat pump, Melco HVAC Services of Orlando can have that repaired the same day. A TXV failure can either result in over or under feeding refrigerant. Overfeeding generally occurs from restricted airflow which can be the result of dirty indoor coils, dirty filters or a bad indoor fan. Underfeeding can occur when there is something blocking the orifice of the TXV. The valve may be adjusted too far closed, screen is plugged or the valve has a frozen orifice. Annual maintenance will help to ensure the valve is adjusted properly and clear of any obstructions which are likely to prevent failures. If you suspect your TXV has failed, you should contact us immediately as continued use could cause additional strain on other system components.