To check the thermo switch run-on time:
- Turn heater on and regulate to full heat output. Let heater run for five minutes.
- Push heater flap lever forward until warning light goes out. At the same time start stop watch.
- The heater air and combustion air blowers, controlled by the thermo switch, should run-on 120-240 seconds. This time is for a nomoinal voltage of 12 Volts and an outside temperature of about 68 F/20 C. The run-on time is shorter at lower outside temperatures.
- If the run-on time is too short or the heater does not switch off, install a new thermo switch. The thermo switch is not adjustable.