Henny Penny AHC-990, Technical Manual, Page: 30 / 65

Model AHC-990/993
3-8
3-7. RELAY REPLACEMENT
To avoid electrical shock or property damage, move the
POWER switch to OFF and disconnect main circuit
breaker, or unplug cord at wall receptacle.
1. Using a Phillip’s head screwdriver, remove the four screws
securing the front panel.
2. Pull panel down, pull connectors from the back of it, and
remove panel from unit.
The following checks are performed with the wall
circuit breaker closed and the main power switch in the
ON position. Extreme caution should be taken. Make
connections before applying power, take reading, and
remove power before removing meter leads, or electri-
cal shock could result.
3. With power reapplied, let unit start heating up, or enter
the Tech Mode in Special Program Mode and check the
relays in the output test. (See T-18 in the Tech Mode Sec-
tion)
4. With the component energized (example: air heaters), 0 volts
should show on the output side of the relay, and 12 volts on
the input side.
5. With the component not energized, 208 or 240 volts
should show on the output side of relay, and 0 volts on
input.
6. If voltage varies from steps 4 and 5, remove power to unit,
pull input wires from relay and place leads of meter onto
input wires. Reapply power to unit. When unit is running,
the input wires to relay should show 12 vdc volts. If this
proves true, the relay is faulty and continue onto step 7.
Checkout:
Feb. 2011