These relays are directly or indirectly attached to the compressor run and start terminals. The relay terminal attached to the compressor run terminal is marked R or sometimes M (for motor). The relay terminal, which is attached to the compressor start terminal, is marked S. (See figs. 50 and 51.)
This test is conducted by bypassing the relays.
1. Disconnect power to the unit.
2. Disconnect the relay from the compressor by pulling it off the compressor terminals or by pulling off the wires, connecting it to the compressor run and start terminals. (In most commercial units, the relay is not directly attached to the compressor terminals, instead it is installed in a control box next to the capacitor near the compressor and wired to the compressor terminals.)
3. Disconnect the only power line to the relay and connect it directly to the compressor run terminal.
4. Using a length of wire with alligator clips at each end and a momentary-contact switch in the middle, connect the compressor R and S terminals. (The wire should be twelve gauge or heavier.)
5. Reconnect power to the unit and depress the switch for no longer than three seconds and release it. If the compressor starts and remains running, the relay must be replaced.