Left & Right Ptc Heater - Bunn Ultra NX Service & Repair Manual

Left and Right PTC Heater
FIG. 16 DEFROST HEATER/PTC
Location:
The defrost heater is located inside a slot at the
rear of each cooling drum assembly. The defrost
heater is covered over with pipe insulating cork
tape.
NOTE: The above pictorial has one auger motor
hidden to show location of a defrost heater.
Rear Cover Removal:
1. Remove 4 screws securing rear cover.
2. Grab cover and pull away from machine.
Test Procedures:
NOTE: Going to check cooling drum defrost heater
for real time temperature change by feel and real
time temperature reading in software program
test menu.
1. Drain hopper and wipe down cooling drum
being checked.
2. Enter the software program and scroll to main
"Service Tools" menu.
3. Press the "Right Dot" switch to answer "Yes".
4. Press the "Center Dot" switch to advance onto
"Test Outputs" menu.
5. Press the "Right Dot" switch to answer "Yes".
6. Press the "Center Dot" switch to scroll through
the menus until "LEFT PTC 74°" menu is
displayed.
SERVICE - REAR COVER COMPONENTS
NOTE: The "LEFT PTC 74°" menu will allow
the operator or technician to test the operation
of the defrost heater while displaying real time
cooling drum temperature on the upper right
corner of the test menu.
7. Place hand on the rear right side of the cooling
drum and feel for temperature change when you
turn on the defrost heater in the next step.
8. Press the "Left Dot" switch to answer "ON". The
defrost heater is turned on, wait approximately
1 minute for temperature to change 1 degree on
the display or feel the temperature change on
the cooling drum.
No temperature change, check defrost heater/
PTC for power before replacing defrost
heater/PTC.
Yes temperature increases, defrost heater/PTC
is good.
9. Press the "Center Dot" switch to advance onto
"RIGHT PTC 74°" menu.
10. Repeat steps 7 & 8 to verify operation of Right
Defrost Heater/PTC.
Defrost Heater/PTC Ratings
Ultra NX 120V Models:
Heater Assembly, PTC 120V ULTRA NX
RESISTANCE: 350-450 OHMS
VOLTAGE: 120VAC
Ultra NX 200-240V Models:
Heater Assembly, PTC 230V ULTRA NX
RESISTANCE: 500-600 OHMS
VOLTAGE: 230VAC
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