Thermo Scientific 3721 - Symptoms and Possible Causes

4-2 Low Temp Incubator Thermo Scientific
Section 4
Service
Temperature variations at set point (poor control):
Excessive ambient temperature variations (see Solution 10)
Compressor Relay failure (see Solution 12)
No air circulation in chamber; inoperative fan (see Solution 1)
RTD Temperature Probe Location (see Solution 5)
Ice buildup on evaporator coils (see paragraph on "Defrosting")
RTD Temperature probe (see Solution 3, Step D and/or Solution 4).
Power Supply PCB Assembly (see Solution 3)
Does not reach a high set point temperature:
No air circulation in chamber; inoperative fan (see Solution 1)
Low line voltage, less than 110V (see Solution 9)
RTD Temperature Probe (see Solution 3, Step D and/or Solution 4).
Power Supply PCB Assembly (see Solution 3)
Overcharged compressor (see Solution 11)
Differences between Temperature Set and Digital Temperature Readout:
(see performance figures, page 3)
RTD Temperature Probe (see Solution 3, Step D and/or Solution 4).
Malfunctioning Power Supply PCB assembly (see Solution 3)
Takes an extremely long time to reach high temperature set point:
No air circulation in chamber; inoperative fan (see Solution 1)
Low line voltage, less than 110V (see Solution 9)
Power Supply PCB assembly (see Solution 3)
Overcharged Compressor (see Solution 11)
Display indicates or
Malfunctioning RTD Temperature Probe (Solution 4)
Symptoms and Possible
Causes (continued)