A TEV bulb which becomes detached from the suction line will cause these symptoms...

A TEV bulb which becomes detached from the suction line will cause these symptoms...

• A. High suction pressure and high discharge pressure
• B. High suction pressure and lower than normal discharge pressure
• C. Low suction pressure and low discharge pressure
• D. Low suction pressure and high discharge pressure

Answer: (B)

A TEV (thermostatic expansion valve) meters refrigerant flow to the evaporator based on the temperature sensed by its bulb on the suction line. When that sensing bulb becomes detached, the valve loses the feedback needed to regulate flow. The valve then tends toward the position set by its spring, effectively reducing refrigerant flow to the evaporator. With less refrigerant reaching the evaporator, the evaporator temperature rises and the low-side (suction) pressure climbs higher than normal. At the same time, the compressor isn’t receiving as much refrigerant mass flow, so it doesn’t develop as much head, causing the high-side discharge pressure to fall below normal. So the symptom pattern you’d expect is high suction pressure and discharge pressure that is lower than usual.

A TEV (thermostatic expansion valve) meters refrigerant flow to the evaporator based on the temperature sensed by its bulb on the suction line. When that sensing bulb becomes detached, the valve loses the feedback needed to regulate flow. The valve then tends toward the position set by its spring, effectively reducing refrigerant flow to the evaporator.

With less refrigerant reaching the evaporator, the evaporator temperature rises and the low-side (suction) pressure climbs higher than normal. At the same time, the compressor isn’t receiving as much refrigerant mass flow, so it doesn’t develop as much head, causing the high-side discharge pressure to fall below normal.

So the symptom pattern you’d expect is high suction pressure and discharge pressure that is lower than usual.