Any of the newer hard start kits are very handy for a service technician to have on their truck. They can range from one that is used on a home refrigerator or even small to medium sized refrigeration systems. The popular units for these applications are from ICM controls, unit model 857, 858, or 859, depending on the size of the system. These controls consist of a start capacitor and compressor overload.
The next series and the most popular are the ICM series 856 and 858. They are mostly used on residential air conditioning systems. They are also sized to the size of the system, and installation is very simple if you are able to locate the unit’s run capacitor, locate the common and compressor terminal. The two wires on the start assist simply will parallel that connection. Then you can mount the start assist in the control box.
When we have an extreme hard start problem there are products one step above the ICM 855 and 856. There would be the SUPCO brand 3W1 and 3W2. These units consist of a separate start capacitor and start relay, the relay and capacitor come prewired with instructions on how to install.