Switch-On; Heating Operation; Switch-Off - Webasto AIR TOP 5000 Manual

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UNCTIONAL
3.1.2

Switch-On

The heater control element (fig.3-1) is used to switch the heater on and off, as well as setting the desired temperature.
The control element acts as a thermostat, similar to a dimmer switch. The built in light indicates heater operation status
by illuminating while the heater is on. The indicator light also functions as a diagnostic indicator (flash code) in the event
of a system interruption (see section 6.2 Troubleshooting).
Should the temperature of the intake air be above the selected, rated temperature, only the motor of the combustion
and heating air fan will operate (control idle). Start operation will be initiated with a heating air temperature below the
rated temperature.
Once the heater control element has been turned on, the light on the control element will illuminate, and the ceramic
igniter (glow pin) is activated. The fan motor briefly spins at high speed, then slows down. After approximately 20
seconds, the fuel metering pump starts delivering fuel. After another 25 seconds, once combustion is established the fan
speed starts to vary gradually. If within 2 minutes there is no stable combustion, the heater will purge for 30 seconds and
then repeat the start up sequence. If the heater fails to start after the second attempt, it will enter into an "operation
lockout" mode and shut itself down (see section 3.1.5 Switch-Off upon Malfunction).
3.1.3

Heating Operation

The heater will heat to the desired temperature setting and attempt to maintain it. For more heat, simply rotate the
heater control element dial clockwise and counterclockwise to decrease heat level. A temperature sensor located inside
the heater works in conjunction with the control element to deliver the desired amount of heat. Once the desired
temperature has been reached, heat output is maintained automatically by increasing or reducing fan speed and fuel
delivery.
New settings on the control element are executed by the control unit/heater with a time delay.
3.1.4

Switch-Off

Switching the heater off extinguishes the operation indicator of the control element.
If no fuel has been delivered or if the air heater is in control idle, the air heater is deactivated immediately without run-
down.
If the fuel metering pump is operating, it will be immediately stopped at switch-off. Fan speed remains constant and
then decreases within 30 seconds to approx. 60% of full speed. After the flame has extinguished, the fan speed rises to
maximum speed for 60 seconds and run down for 120 seconds is initiated.
Run-down is at approx. 60% of full speed and is deactivated automatically.
Re-activation of the heater during run-down is permitted. Run-down will be completed first with a subsequent restart.
3-2
ESCRIPTION
ATTENTION!
ATTENTION!
ATTENTION!
A T 5000
IR OP