Thermostats And Temperature Probes - Frymaster 45 Series Service And Parts Manual

FREQUENTLY USED TEST POINTS FOR 45 SERIES INTERFACE BOARDS
Test
12 VAC Power to Controller
24 VAC Power
24 VAC Power to Gas Valve
120 VAC Power
Probe Resistance*
** Disconnect 15-Pin harness from controller before testing probe circuit.
** See Probe Resistance Chart at end of chapter.
Four LEDs, arranged across the top of the boards and identified in the table below, are provided to
assist in troubleshooting.
Every board contains one heat relay (K3), and may contain two basket lift relays (K1 and K2). As
shipped from the factory, fryers with bell crank basket lifts will have relays K1, K2, and K3. All
other factory-original fryers will have boards with only relay K3.

THERMOSTATS AND TEMPERATURE PROBES

Different types of thermostats are used in 45 Series fryers, depending on the fryers' configuration.
Fryers equipped with Thermostat Controls have an adjustable controlling (operating) thermostat.
The temperature at which the thermostat opens and closes is adjusted by physically changing the set-
ting of the thermostat itself by means of an attached knob. When new, the Fenwal controlling ther-
mostat used in 45 Series fryers is sensitive to one-degree changes in temperature.
Fenwal thermostats are used in a number of Frymaster™ products. The thermostat
for the 45 Series is 4 inches long. Do not use 3-inch Fenwal thermostats in 45 Series
Fryers equipped with all other type controls have a temperature probe. In these units, the probe
resistance varies directly with the temperature. That is, as the temperature rises, so does resistance at
a rate of approximately 2 ohms for every 1º (F or C). Circuitry in the controller monitors the probe
resistance and controls burner firing when the resistance exceeds or falls below programmed
temperatures (setpoints). The temperatures are programmed by means of a keypad on the face of the
controller.
All 45 Series fryers are equipped with a high-limit thermostat. In the event that the fryer fails to
properly control the oil temperature, the high-limit thermostat prevents the fryer from overheating to
the flash point. The high-limit thermostat acts as a normally closed power switch that opens when
Meter
Setting
50 VAC Scale
50 VAC Scale
50 VAC Scale
250 VAC Scale
R x 1000 OHMS
45 SERIES INTERFACE BOARD
LED DIAGNOSTIC LIGHTS
GV Indicates 24 VAC to the gas valve
AL Indicates open Drain Safety Switch (if installed)
24V Indicates 24 VAC from transformer
COMP Indicates 12 VAC to computer
CAUTION
fryers.
1-3
Pins
1 and 3 of J2
24 VAC Terminals
6 on J1 and GROUND
7 and 12 of J1
2 and 3 of J1
Results
12-18
22-28
22-28
110-125
**