A refrigerant overcharge in a capillary tube air conditioning system will cause these symptoms...

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

Answer: (C)

When a capillary tube system is overcharged, there is more refrigerant in the cycle than the system was designed to handle. The capillary tube provides a fixed restriction, so the compressor pushes a larger mass of refrigerant through the loop. The condenser then has to condense more refrigerant, which raises the high-side (discharge) pressure. At the same time, the evaporator becomes flooded with liquid refrigerant, and the vapor that leaves the evaporator is at a higher saturation pressure than normal, causing the low-side (suction) pressure to rise as well. So both sides operate at higher pressures than intended, which is why the symptoms described are high suction pressure and high discharge pressure.