Question

The customer complaint is not enough heat. You install service gauges and find the low side pressure is higher than normal and the high side pressure is lower than normal. You switch the system to the cooling mode and find the pressures are normal. The most likely cause of the problem is?

1) Low refrigerant charge
2) Faulty expansion valve
3) Dirty condenser coil
4) Faulty compressor

Answer 1

The most likely cause for the customer's complaint of insufficient heat, given the specific pressure readings, is a faulty expansion valve, as it affects the heating mode operation without impacting the cooling mode. The correct answer is Option 2) Faulty expansion valve.

Step-by-step explanation:

When a customer complains about insufficient heat and service gauge readings indicate that the low side pressure is higher than normal while the high side pressure is lower than normal, this typically suggests a problem with a component of the heat pump system. Since the pressures are normal in the cooling mode, this indicates that the issue is only present in the heating mode. The most likely cause of this problem, when considering the operation of a heat pump, is a faulty expansion valve. Low refrigerant charge would affect both heating and cooling operations, a dirty condenser coil would cause high pressure on the high side, not low, and a faulty compressor would likely cause issues in both modes of operation. Thus, option 2, faulty expansion valve, is the most probable cause.