HVAC Excellence Commercial Air Conditioning ESCO Certification Practice Exam 2026 – Your All-In-One Guide to Success!

When a thermal expansion valve (TEV) sensing bulb loses its charge, it cannot accurately sense the temperature of the refrigerant. This loss results in a malfunctioning valve that does not adjust properly to varying load conditions. Consequently, the TEV may remain in a fully open position, leading to an excessive amount of refrigerant flowing into the evaporator.

As the evaporator receives too much refrigerant, it may struggle to absorb adequate heat, resulting in a low saturation temperature. This condition can cause the system to operate at a very low suction pressure because the excess refrigerant flooding the evaporator does not facilitate efficient heat exchange. The system will not be able to vaporize the liquid refrigerant properly, leading to a low pressure in the suction line, which can cause issues such as reduced cooling capacity, compressor flooding, and potential damage.

Understanding this behavior of the TEV and its relationship with the suction pressure is crucial for proper HVAC system maintenance and troubleshooting.