Valeo Thermo H 160, Руководство по ремонту

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Thermo H plus 4 Functions of the heater
4 Functions of the heater
4.1 General functional description of the
heater
The Thermo H plus hybrid heater integrates two different
and independent each other coolant heating systems:
1. Generation of heat by burning liquid fuel via the diesel
burner head - further referred to as D heater.
2. Generation of heat by electrically operated heating
cartridges via the HV control head - further referred to
as HV heater.
Both transmit heat to the coolant circuit via the common
heat exchanger.
Also the function and control of the two systems is inde -
pendent of each other and is therefore also explained
separately for the systems.
4.2 HV heater
NOTE:
The following functional sequence applies to the opera -
tion of the HV heater with AC or DC or both.
4.2.1 Switching on
24V DC must be connected to the HV control wiring
harness according to the valid wiring diagram for external
control by an operating or control element (for example,
switch, relay, pre-selection timer) installed on the vehicle
in order to switch on the HV heater.
This power is fed to the load contactor(s), the control ther -
mostat and the overheat protection (see 3.2 ).
They constitute the control loop of the HV control head.
If all of the following three conditions are met:
1. 24V DC is applied to the external control input,
2. The control thermostat has not yet reached the upper
switching threshold / has fallen below the lower swit -
ching threshold,
3. The overheating protection has not yet reached the
upper switching threshold,
the respective contactor is activated, the moving core
attracts and closes the main contacts.
In this way the heating cartridges connected to the
contactor are powered.
The heating cartridges now convert the electrical energy
into heat.
4.2.2 Heating operation
The control thermostat opens its contact at 75°C and
closes it again at 68°C. In this way, the heating operation
is regulated.
The overheat protection opens its contact at 125°C and
must be mechanically reset by service personnel.
ATTENTION:
After the overheating protection has been triggered,
the cause of the overheating must first be removed
before it is reset.
4.2.3 Switching off
When the 24V DC control voltage at the external control
terminal is interrupted by a vehicle installed control
element (e.g. switch, relay, pre-selection timer), the load
contactor opens and the voltage supply of the heating
cartridges is switched off.
The circulating pump in the coolant circuit continues its
operation for approx. 120s.