Specifications

27 Barnstead |Thermolyne • 800-553-0039
Problem Solving
The Problem Solving section is intended to aid in defining and correcting possible service problems.
When using the chart, select the problem category that resembles the malfunction. Then proceed to the
possible causes category and take necessary corrective action.
Problem Probable Causes Corrective Action
The cycle light does not
illuminate.
The furnace is not connected to
power supply.
ON and OFF power switch is
defective.
Door switch defective.
Incorrect power source.
Defective circuit breaker.
Check furnace connection to
power source.
Replace power switch.
Re-align or replace furnace door
switch.
Check power source.
Replace circuit breaker.
The furnace does not heat. No power.
Defective electrical hookup.
Thermocouple has oxidized and
opened the circuit.
Controller malfunction.
Two or more heating elements in
208V or 240V furnaces are
burned out.
Door switch malfunction.
Defective safety relay.
Defective solid state relay (SSR)
Check power source and fuses
or breakers.
Repair electrical hookup.
Replace thermocouple.
Contact Thermolyne customer
service.
Replace defective elements.
Re-align or replace door safety
switch.
Replace safety repay.
Replace SS relay.
Slow heatup. Low line voltage.
Heavy load in chamber.
Wrong heating element
One or more heating elements
are burned out.
Wired improperly.
Install line of sufficient size and
proper voltage (Isolate furnace
from other electrical loads).
Lighten load in chamber to allow
heat to circulate.
Install proper element.
Replace burned out elements.
Check wiring diagram for correct
wiring of your furnace.
Door switch does not cut power
to the furnace chamber.
Door switch is not functioning.
Safety relay malfunction.
Re-align or replace door safety
switch.
Replace safety relay.
Controller overtemperature alarm
does not control power to
furnace chamber.
Alarm output defective. Replace control module (contact
Thermolyne).