An expansion-valve kit has been developed to match the evaporator unit. The expansion valve is equipped with a bleed port. This permits pressures to equalize after the compressor stops. This means the compressor can restart in an unloaded condition. Flare fittings permit connections on the valve in a simple field installation.
Since single-phase models require large amounts of current, they can cause lights to blink when they start up. A positive temperature coefficient (PTC) kit can eliminate some of the start-up problems. It consists of a solid-state circuit with a ceramic thermistor. The thermistor provides extra starting torque to solve most compressor hard starting problems such as low voltage or light dimming. It switches itself out of the circuit after start-up.
A start kit consisting of a start capacitor and potential relay must be installed in some models when used with certain evaporator units and expansion-valve kits. The added capacitance is taken from the circuit when the coil energizes almost instantly.
However, it does help with the starting load. Since the coil is energized whenever the air-conditioner system is operating, it is possible for the coil to become open. This causes the start capacitor to “blow-up” and spread its contents inside the control housing. Replacement of the capacitor and the coil of the relay is necessary in order to repair the equipment for proper operation. Usually the entire relay must be replaced, since the coil is not always available separately.