Carbolite VMF Series - Manual (Page 12)

AAF, GSM, VMF
12 MF06 – 3.32
6.0 F AULT A NALYSIS
A. Furnace Does Not Heat Up
1. The HEAT light
is ON
 The heating
element has failed
 Check also that the SSR is working
correctly
2. The HEAT light
is OFF
 The controller
shows a very high
temperature or a
code such as S.br
 The thermocouple has broken or has a
wiring fault
 The controller
shows a low
temperature
 The door switch(es) (if fitted) may be
faulty or need adjustment
 The contactor (if fitted) may be faulty
 The SSR could be failing to switch on due
to internal failure, faulty logic wiring from
the controller, or faulty controller
 There are no lights
glowing on the
controller
 Check the supply fuses and any fuses in the
furnace control compartment
 The controller may be faulty or not
receiving a supply due to a faulty switch or
a wiring fault
B. Furnace Overheats
1. The HEAT light
goes OFF with
the instrument
switch
 The controller
shows a very high
temperature
 The controller is faulty
 The controller
shows a low
temperature
 The thermocouple may have been shorted
out or may have been moved out of the
heating chamber
 The thermocouple may be mounted the
wrong way round
 The controller may be faulty
2. The HEAT light
does not go off
with the
instrument
switch
 The SSR has failed
“ON”
 Check for an accidental wiring fault which
could have overloaded the SSR