Tracing Oven Temperature Sensor Faults; Tracing Thermal Limiter Faults - Fisher & Paykel Titan Aerotech OD302US Service Manual

Service Manual 546596A: 302 Series Titan Oven

5.23 Tracing oven temperature sensor faults

(Refer to Technical Overview Section 2.16)
PROCEDURE:
1. Enter the Technician Mode diagnostics to view the cavity temperature reading. (refer
to Diagnostics Section 4.3)
2. Record the cavity temperature reading and substitute the oven temperature sensor
with a new sensor. (refer to Servicing Instructions Section 7.12)
3. Record the cavity temperature reading from the new sensor.
If there is a significant difference between the two temperature readings (>10°F or
>5°C), leave the new sensor in.
4. If the two temperature readings are similar (±10°F or ±5°C) check the temperature
sensor wiring connectors and connection to the power module.
If the wiring is good, refit the original temperature sensor.
temperature sensor is not faulty.
5. If the fault persists, test the power module by substituting a 1000 ohm 5% resistor
across pins 1&2 on the 'Sensors' connector. (refer to Technical Overview Section
2.25 for pin numbering) The temperature display should read 32°F + 10°F (0°C+
5°C).
Replace the power module if the displayed reading is incorrect. (refer to Servicing
Instructions Section 7.9)

5.24 Tracing thermal limiter faults

(Refer to Technical Overview Section 2.28)
Note: In the event of a thermal limiter tripping, it is important that the cause be
located and rectified.
PROCEDURE:
1. Do a continuity test between L2 (for US products), Neutral (for NZ/AUS products) or
P2 (for EU products) and the terminal block side of the isolating relay.
If there is no continuity then this indicates a thermal limiter has tripped.
Note: To do a quick check for a tripped microtemp limiter test for 12
connector into the power module from the transformer. (refer to Technical Overview
Section 2.25)
2. To locate the tripped thermal limiter check for continuity across the limiter contacts.
Note: (EU products only) Check for continuity across both paths of the 2 pole limiter.
3. Replace the faulty thermal limiter/s with one having the same trip temperature. (refer
to Servicing Instructions Section 7.11)
4. Trace the component that is most likely to have caused the thermal limiter to trip.
To trace the likely cause of tripping
1. Determine the likely faulty component.
2. Trace the component fault.
Note: Thermal limiters are positioned in specific areas to detect certain components
failing. The limiter positions and the components they monitor are listed in the Technical
Overview Section 2.28.
These are the most likely causes of a thermal limiter tripping:
Faulty cooling fan (stopped running).
Faulty element (element run-away).
Faulty temperature sensor (incorrect reading)
Refer to Section 5.19
Refer to Section 5.22
Refer to Section 5.23
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June 2005
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