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Troubleshooting
309524N 17
Troubleshooting
Problem Cause Solution
Heater will not heat. No current. Check circuit and fuses.
Check continuity of primary thermo-
stat (24), backup thermostat (10),
and thermal limit sensor (15).
Check continuity of thermostat (10)
and heater block (3) terminals - Page
18.
Burned out heater block (3). Replace block - Page 20.
Blown heat limiter (15). Check continuity of primary thermo-
stat (24) and backup thermostat (10).
Replace thermostats if necessary
when replacing thermal limit sensor
(15) - Pages 18-20.
Temperature too low. Fluid requires more warm-up time. Increase warm-up time.
Wrong temperature setting. Adjust setting - Page 15.
Flow rate too high. Reduce flow rate or use 2 heaters.
Clogged fluid passages. Flush regularly - Page 16.
Temperature too high. Wrong temperature setting. Adjust setting - Page 15.
Failed primary thermostat (24). Replace - Page 18.
High fluctuating temperatures, about
220-250°F (104-120°C) at 0.1 GPM.
Primary thermostat (24) contacts
sticking.
Replace thermostats (24, 10) - Page
18. Note that backup thermostat (10)
keeps heater functioning for only a
short time.
Too much pressure drop or fluid will
not flow.
Flow rate too high. Reduce flow rate or use 2 heaters.
Clogged fluid passages. Flush regularly - Page 16.
Heater fittings leak. Loose or damaged fittings. Tighten fittings or replace heater
block - Page 20.
FIG. 14: Electrical Schematic
F
R
300°F
230°F
255°F
(110°C)
OFF
a
1
e
2
(149°C)
(124°C)
e
1
SL
Mp
R
6-55 ohm
05556-524