A TEV overfeeding condition can be caused by which of the following sensor problems?

A TEV overfeeding condition can be caused by which of the following sensor problems?

• A. Oversized TEV
• B. High ambient temperature
• C. TEV sensing bulb not making good thermal contact
• D. Leaking refrigerant valve seats

Answer: (C)

The unit that controls refrigerant flow uses a sensing bulb attached to the evaporator or suction line to read the evaporator temperature and maintain the desired superheat. When the sensing bulb has good thermal contact, it accurately mirrors the evaporator conditions and the valve modulates to keep the load in check. If the bulb is not in good thermal contact, the temperature it senses becomes inaccurate, so the valve misreads the evaporator load and tends to stay open longer to compensate. That extra opening delivers more refrigerant than the evaporator can absorb, causing an overfeeding condition. The other options aren’t sensor problems: an oversized valve is a sizing issue, high ambient temperature affects the condenser side, and leaks at valve seats are refrigerant losses, not sensing failures.

The unit that controls refrigerant flow uses a sensing bulb attached to the evaporator or suction line to read the evaporator temperature and maintain the desired superheat. When the sensing bulb has good thermal contact, it accurately mirrors the evaporator conditions and the valve modulates to keep the load in check. If the bulb is not in good thermal contact, the temperature it senses becomes inaccurate, so the valve misreads the evaporator load and tends to stay open longer to compensate. That extra opening delivers more refrigerant than the evaporator can absorb, causing an overfeeding condition. The other options aren’t sensor problems: an oversized valve is a sizing issue, high ambient temperature affects the condenser side, and leaks at valve seats are refrigerant losses, not sensing failures.