Service manual

Electrical System Section 6
6-28
Part No. 80-1206-3
Diagnosing Start Components
If the compressor attempts to start, or hums and trips the
overload protector, check the start components before
replacing the compressor.
CAPACITOR
• Visual evidence of capacitor failure can include a
bulged terminal end or a ruptured membrane. Do not
assume a capacitor is good if no visual evidence is
present.
• A good test is to install a known good substitute
capacitor.
• Use a capacitor tester when checking a suspect
capacitor. Clip the bleed resistor off the capacitor
terminals before testing.
RELAY
The relay has a set of contacts that connect and
disconnect the start capacitor from the compressor start
winding. The contacts on the relay are normally closed
(start capacitor in series with the start winding). The
relay senses the voltage generated by the start winding
and opens the contacts as the compressor motor starts.
The contacts remain open until the compressor is de-
energized.
Relay Operation Check
1. Disconnect wires from relay terminals.
2. Verify the contacts are closed. Measure the
resistance between terminals 1 and 2. No continuity
indicates open contacts. Replace the relay.
3. Check the relay coil. Measure the resistance
between terminals 2 and 5. Not resistance indicates
an open coil. Replace the relay.
!
Warning
Disconnect electrical power to the condensing unit
before proceeding.