What are the pressures on a heat pump in off mode?

In off mode, the pressures in a heat pump should have equalized. This means that the pressures on both the high and low sides of the system have reached a steady state and there is no active transfer of refrigerant. The high pressure side of the system, where the refrigerant is compressed, should be at the same pressure as the outdoor ambient air. The low pressure side, where the refrigerant is evaporated, should be at a slightly higher pressure than the outdoor air, usually around 100 to 200 PSI (pounds per square inch) above the ambient pressure. This slight pressure difference is maintained to prevent any possible reverse flow of refrigerant through the system.