1. Factors of low suction pressure:

The suction pressure is lower than normal due to insufficient cooling capacity, low cold load, low expansion valve opening, low condensing pressure (with capillary system), and filter obstruction.

Factors of high suction pressure:

The suction pressure is higher than the normal value because of excessive refrigerant, large cooling load, large expansion valve opening, high condensing pressure (capillary system), and poor compressor efficiency.

2, exhaust pressure, exhaust pressure high factors:

When the exhaust pressure is higher than the normal value, there are generally small flow of the cooling medium or high temperature of the cooling medium, too much refrigerant charging, large cooling load and expansion valve opening degree.

These causes the circulation flow rate of the system to increase and the condensing heat load to increase accordingly. Because the heat cannot be dissipated in time, the condensation temperature rises, and the exhaust (condensation) pressure rises can be detected. In the case of low flow of cooling medium or high temperature of cooling medium, the cooling efficiency of condenser decreases and the condensation temperature rises.

In the case of low flow of cooling medium or high temperature of cooling medium, the cooling efficiency of condenser decreases and the condensation temperature rises. The reason for excessive refrigerant charge is that the excess refrigerant liquid occupies part of the condensate pipe, which reduces the condensation area and causes the condensation temperature to rise.

Factors of low exhaust pressure:

The exhaust pressure is lower than the normal value, because of low efficiency of the compressor, insufficient refrigeration dose, small cooling load, small expansion valve opening, the filter is not smooth, including the expansion valve filter screen and low temperature of cooling medium.

The above factors will reduce the cooling flow and condensing load of the system, resulting in a decrease in the condensing temperature.

From the above mentioned inspiratory pressure and exhaust pressure changes, they have a close relationship. Under normal circumstances, the suction pressure increases, the exhaust pressure also rises accordingly; The suction pressure drops and the exhaust pressure drops accordingly. The general discharge pressure can also be estimated from changes in the suction gauge.