Valeo Thermo AC 070 Instruction manual

Rev. 03/2019
Id.No. 11123153C
Thermo AC 070
Thermo AC 200
Thermo DC 200
Workshop Manual
HEATING SYSTEMS

1
Thermo AC/DC Table of contents
1 Introduction
1.1 Content and purpose 101
1.2 Effectivity of the workshop manual 101
1.3 Meaning of highlighted content 101
1.4 Symbols 101
1.5 Further documentation to be used 101
1.6 Safety information and regulations 101
1.6.1 Required qualifications 101
1.6.2 Emergency stop / de-energizing 102
1.6.3 Work at the heater 102
1.6.4 Other safety information 102
1.7 Suggestions for improvement and change 102
2 Technical data
3 Description of assemblies and components
3.1 HV Control head 302
3.2 Small distribution board 302
3.3 Heat exchanger 303
3.4 Heating cartridges 303
3.5 Control thermostat 303
3.6 Temperature limiter 304
4 Functions of the heater
4.1 General functional description of the heater 401
4.2 Functional sequence of the heater 402
4.2.1 Switching on 402
4.2.2 Heating operation 402
4.2.3 Switching off 402
4.3 Malfunctions caused by overheating / tripping of the temperature limiter 402
5 Troubleshooting and error correction
5.1 Allgemeines 501
5.2 General error symptoms 501
5.3 Error symptom “Total failure of the heater“ 503
5.4 Error symptom “Heating power too low or permanent operation“ 504
5.5 Error symptom „Overheating / the temperature limiter has tripped“ 505
5.6 Error symptom „Over heating“ 505
5.7 Error symptom “ISO value too low (unacceptable)“ 506
5.8 Individual component tests 507
5.8.1 General visual inspection 507
5.8.2 Heat exchanger visual inspection 507
5.8.3 Voltage converter check or visual inspection 507
5.8.4 Load contactor check or visual inspection 507
5.8.5 Heating cartridges check or visual inspection 507
5.8.6 Check of the temperature guards (control thermostat and temperature limiter) 507
6 Wiring diagrams
6.1 General 601

2
Thermo AC/DC Table of contents
7 Servicing
7.1 General 701
7.2 Heater servicing 701
7.2.1 Periodical heater maintenance 701
8 Components and heater removal and installation
8.1 General 801
8.2 Temperature guards (temperature limiter, control thermostat removal/installation. 802
8.3 Hood removal/installation 803
8.4 Housing removal/installation (incl. cable connections) 803
8.5 Small distribution board removal/installation 803
8.6 Heating cartrides/screw plugs removal/installation 806
8.7 HV wiring harness (AC/DC) removal/installation 807
8.8 LV DC control wiring harness removal/installation 807
8.9 Heater removal/installation 808
8.10 Heat exchanger removal/installation 808
8.11 Bleeding of the coolant circuit 809
9 Modifications and retrofits
9.1 General 901
10 Packing/storage/shipping
10.1 General 1001
Appendix
Periodic heater maintenance A-1

101
Thermo AC/DC 1 Introduction
1Introduction
1.1 Content and purpose
This workshop manual is used during maintenance and
repair of water heaters (further referred to as heaters)
Thermo AC070, 200 und Thermo DC200.
Electrical work may only be performed by persons,
which have the required qualification (see 1.6.1).
ATTENTION:
Work on the heater may only be performed by briefed
and/or trained by Valeo personnel.
1.2 Effectivity of the workshop manual
The workshop manual applies to heaters listed on the title
page of this document.
It may be subjected to modifications and amendments.
The respectively currently effectife version is binding. This
version can be found on the Valeo Bus homepage under
Service/Downloads/Heating Systems.
1.3 Meaning of highlighted content
Throughout this manual the emphasized words Warning!,
Caution!, ATTENTION: and NOTE: used as follows:
This caption is used to indicate possible severe inju-
ries or fatal accidents if instructions or procedures
are carried out incorrectly or entirely disregarded.
This caption is used to indicate possible minor inju-
ries if instructions or procedures are carried out
incorrectly or entirely disregarded.
ATTENTION:
This caption points to actions which may cause ma-
terial damage.
NOTE:
This caption is used to draw attention to an important
feature.
1.4 Symbols
1.5 Further documentation to be used
The use of additional service literature is required.
References are provided in the workshop manual at
appropriate locations.
Use the following documents during operation and main-
tenance of the heaters:
• Installation and operating instructions Thermo AC/DC
• Spare parts list Thermo AC/DC
• Technical Information (TI)
This service literature is also available at www.valeo-ther-
malbus.com/Service/Downloads/Heating Systems or
.../Service/Spare Parts & Accessories/Heating Systems
for download.
1.6 Safety information and regulations
Basically, general accident pevention provisions and the
valid industrial safety directions must be adhered to.
"General Safety Regulations" which exceed the frame-
work of these provisions are listed below.
The specific safety regulations which affect the present
manual are issued highlighted in the individual sections or
procedures.
1.6.1 Required qualifications
Electrical work may only be performed by a qualified
electrician for HV systems in motor vehicles, crafts-
man, activity with repetitive character. Training acc.
to DGUV 200-005 (previously BGI 8686), at least level
2.
Danger to life and health!
Warning!
Danger to life and health!
Warning!
Hazardous to health!
Caution!
Symbol tightening torque value:
Identifies in graphics parts (eg nuts, bolts)
that are to be mounted with a specific tigh-
tening torque. The torque values are
shown at the symbol and are binding.
High voltage!
Danger to life!
Warning!

102
Thermo AC/DC 1 Introduction
NOTE:
The provisions of these Regulations are binding within the
territory governed by DGUV Regulations and should
similarly be observed in countries without specific regula-
tions.
Country specific rules / standards are to be considered
additionally.
Even before the start of non-electrical work, the
voltage- freeness must be determined by a skilled
electrician.
1.6.2 Emergency stop / de-energizing
The Thermo AC/DC heaters itself do not have an emer-
gency stop system. Their control and power supply is
integrated into the vehicle's electrical system.
It is therefore the responsibility of the user to inform
himself before the commisioning of the heater in the
vehicle how the heater can be successfully de-energized
if necessary (maintenance, service work, abnormal beha-
vior etc.).
1.6.3 Work at the heater
Installation, maintenance and repairs may only be
carried out when the vehicle's engine is not running
and the high voltage supply (AC/DC) / power supply is
switched off.
Before starting the work at the heater, it is to make
voltageless acc. to DIN VDE 0105-100 and this state
must be ensured for the duration of the work.
The following safety precautions must be observed:
– switch off the power supply to the heater
– ensure it cannot be switched on again
– verify system is voltage-free, all poles
– ground and short circuit (the de-energized circuit)
– cover or block neighbouring parts under voltage
Electrical cables and operating elements of the heater
must be arranged in the vehicle in such a way that
their functioning is faultless under normal operating
conditions and cannot be hampered.
Work at electrical equipment may only be started if
protective measures against electric shock, short
circuits and arcing faults have been carried out.
Familiarize yourself with the Thermo AC/DC Installa-
tion instructions before you make any modifications
to the existing heater installation.
NOTE:
The Installation and operating instructions contain the
statutory regulations and other safety hints and regula-
tions for the proper installation of the heater.
Further they contain safety instructions and regulations to
be followed for safe operation of the heater.
1.6.4 Other safety information
1.6.4.1 Temperature sensors
ATTENTION:
The cables of the temperature sensors (temperature
limiter, control thermostat) may not be mechanically
stressed (pull on the cable, carry the heater at the
cable etc.).
1.7 Suggestions for improvement and
change
Please direct any complaints, improvement or modifica-
tion suggestions regarding this manual to:
service-valeo[email protected]
High voltage!
Danger to life!
Warning!
High voltage!
Danger to life!
Warning!
Danger to life and health!
Warning!
STOP!

201
Thermo AC/DC 2 Technical data
2 Technical data
Except where limit values are specified, these technical data refer to the usual heater tolerances of ±10% at an ambient
temperature of +20°C and at the rated voltage.
Table 201 Technical data
Heater Thermo AC070 Thermo AC200 Thermo DC200 Thermo DC200 Thermo DC200
Kind of design electrical operated heater
Heater Ident.-No. 11117427 11116255 11117083 11122596B 11126153A
Ambient temperature during
operation °C -40...+ 85
Storage temperature °C -40...+ 90
Operating overpressure bar max. 2.0
Capacity of the heat exchanger l 9.9 9.4
Minimum water flow l/h >1500
Minimum capacity of the water
system l25
Antifreeze ratio in the cooling
system %30 - 60
Device dimensions
(tolerance ± 3 mm) mm length: 578 / wide: 247 / height: 225
Weight kg 12.5 15
Heater (electrical system) Thermo AC070 Thermo AC200 Thermo DC200 Thermo DC200 Thermo DC200
Nominal heating flow kW 7 20
Nominal voltage VDC 3/PE/N AC 400/230V 690 486
Power consumption kW 6.6 20
Frequency Hz 50 - 60 --
Nominal current A 10 30 29.6 41.7
Rated current at 540V DC A -- 23.2 34.4@400V
Rated current at 690V DC A -- 29.6 41.7@486V
Rated current at 750V DC A -- 32.2 46.4@540V
Rated current at 900V DC A -- -- 38.6 51.5@600V
Type of electrical protection
Circuit
breaker all
pole 16A
Circuit
breaker all
pole 32A
1000V DC/
xxA/10kA
fast-blow
1000V DC/xxA/10kA fast-blow
Circuit breaker rating A 16 32 35 50* 60*
Continued on next page

202
Thermo AC/DC 2 Technical data
*NOTE:
The circuit breaker rating is based on the maximum operating voltage of 900V DC. The rating must be adapted to the highest
operating current and the temperature derating of the circuit breaker.
The minimum cable cross-sections specified in the table
must be observed.
* Cable cross-section must be reduced again to 0.75 or 2.5mm² in front
of the heater.
Operating voltage range HV VDC -- 450 - 750 0 - 900 0 - 600
Cross section HV supply cable mm² -- 4 6 10
HV wiring harness at heater side -- 2ea wire
ferrules 4mm²
2ea wire
ferrules 6mm²
2ea wire
ferrules 10mm²
Min. cable cross section at
vehicle side
mm² 5x4 4 6 10
Total resistance of all HV heating
cartridges ΩL-N: 23.3 L-L: 46.6
L-N: 7.8
L-L: 15.5 23.3 23.3 11.65
Insulation resistance new device
at 1000V MΩ>100
Insulation resistance end of life
at 1000V MΩ>50
Control signal nominal voltage VDC 24 -- -- 24
Operating voltage range LV VDC 19.2 - 26.4 -- -- 16 - 32
Max. control current LV A 0.55 0.42 1.58
LV circuit breaker current rating A 5
LV control harness connector FEP 42064500 AMP HDSC 8 pin 1-1418479-1
Mating connector FEP 42121100 AMP HDSC 8 pin 1-1564416-1
or 1-1564512-1
Mating connector Valeo ID No. 11114939_ 11125731_
Heater (electrical system) Thermo AC070 Thermo AC200 Thermo DC200 Thermo DC200 Thermo DC200
Cable length <7.5m Cable length 7.5 - 15m
0.75 mm² 1.5 mm² *
2.5 mm² 4.0 mm² *
continued

301
Thermo AC/DC 3 Assemblies and components
3 Description of assemblies
and components
The fully electrical water heaters Thermo AC/DC operate
independently of the vehicle engine and are connected to
the vehicle’s cooling and electrical systems. Thus, they
can be used in a depot for pre-heating purposes. For this
the AC heater is connected stably to the depot mains 3/
PE/N AC 400/230V 50Hz. Further more the heaters also
can be used in electric driven buses or hybrid buses
where a 600 (690) VDC (DC heaters) or a 3/PE/N AC 400/
230V 50Hz (AC heaters) power supply is provided in
association with the vehicle‘s own heating system:
– to heat the passenger cabin, and
– for pre-heating.
The heaters are approved for horizontal installation only.
Fig. 301 Heater overview
1
2
3
45
7
8
9
6
1 HV-Control head
2 Heat exchanger
3 Water, inlet
4 Temperature limiter
5 Water, outlet
6 Control thermostat
7 Control line connection
8 Power supply connection
9Hood

302
Thermo AC/DC 3 Assemblies and components
The heater is bolted down to the vehicle chassis or is
secured using an additional cross beam.
The heat is generated by the heating of heating cartridges
by means of electrical energy. The heating cartridges are
part of the heat exchanger and are therefore integrated
directly into the coolant circuit. As a result, the generated
heat can pass into the cooling circuit without loss.
The adaptation to the changing demand of heat is
reached by intermittent operation (intermittend mode).
In pronciple the heaters of the Thermo AC/DC series
consist of the main components:
• HV Control head
• Small distribution board
• Heat exchanger
• 3, 6 or 9 heating cartridges
• Temperature sensors
3.1 HV Control head
The HV control head consists of an aluminum die-cast
ring and the hood. Inside is the small distribution board.
The heat exchanger is screwed to the rear of the control
head.
3.2 Small distribution board
The small distribution board consists of a 35mm standard
rail on which the electrical components required for the
heater are mounted (see Fig.302 and Fig. 303).
The standard rail is attached to the heat exchanger by
means of stay bolts.
Fig.302 Example of a small distribution board of AC heaters (version with power supply unit)
Feed-through terminal blocks
Load contactor AC-DC Converter
Fuse
Ground terminal block
Standard rail
terminal block

303
Thermo AC/DC 3 Assemblies and components
3.3 Heat exchanger
In the heat exchanger (1, Fig. 304) the water flowing
through is heated by heating cartridges (6) arranged in it.
The cylindrically welded construction has a water inlet (2)
and a water outlet (3). The heater is integrated into the
cooling water circuit via these two connection ports.
In the water outlet (3) the control thermostat (4) is screwed
in. In the wall of the heat exchanger the temperature
limiter (5) is installed.
The plate at the front has receiving openings with threads
for the heating cartridges (6).
3.4 Heating cartridges
At the end of the rod-shaped, water-proof heating cart-
ridges (6, Fig. 304) there is an external thread with a
hexagon for screwing in and the electrical cables are led
out.
ATTENTION:
The heating cartridges must always be screwed in
with a new gasket!
3.5 Control thermostat
The control thermostat (4, Fig. 304) captures the coolant
temperature at the heat exchanger outlet.
Fig. 303 Example of a small distribution board of DC heaters
Standard Rail
Feed-through
Load contactor
DC-DC Converter
Flyback diode
3 ea Double feed-through terminal blocks
1 ea Feed-through terminal block
terminal blocks
1 ea Fuse holder

304
Thermo AC/DC 3 Assemblies and components
The signal is transmitted to the load contactor, where it is
processed.
The shutdown is carried out at 75 ± 3 °C, the restart is
carried out at 68 ± 5 °C.
3.6 Temperature limiter
The temperature limiter (5, Fig. 304) protects the heater
from unacceptably high temperatures. The temperature
limiter switches off the heater at a temperature greater
than 125 °C .
The temperature limiter is mechanically resettable at a
temperature <90 °C.
Fig. 304 Heat exchanger with installed on/in it components (exploded)
1
23
4
5
6
1 Heat exchanger
2 Water, inlet
3 Water, outlet
4 Control thermostat
5 Temperature limiter
6 Heating cartridges

401
Thermo AC/DC 4 Functions of the heater
4 Functions of the heater
4.1 General functional description of the
heater
In the fully electrical operated heater Thermo AC/DC the
coolant of the vehicle is heated by electric heating cart-
ridges.
Control elements to switch the heater on and off can be:
– Switches
– Relays
– Valeo preselection timer
To monitor the operation an operation indicator or the
Valeo preselection timer is to be provided.
The heating cartridges are switched by a load contactor.
The control voltage for the contactor is generated by an
AC/DC converter (integrated in the Thermo AC200/
DC200 in the heater).
On the vehicle side, the control circuit contains an opera-
ting element by means of which the heater is taken into
operation. On the heater side, a control thermostat and a
temperature limiter are integrated, which are attched to
the heater. In operation, they enable the heating cart-
ridges to be switched on automatically when a lower swit-
ching threshold is reached and their switching off when
the upper switching threshold is reached (regulating ther-
mostat) as well as a switching off of the heater in the event
of an overheating (temperature limiter). Table 401 shows
the corresponding default values.
The heater must be protected and monitored on the
vehicle side by a ground fault interrupter (AC) respective
an insulation monitoring device.
Heating is only permitted with a sufficient coolant flow rate
(> 1500 l / h).
When the heater is switched off, ensure that the circula-
ting pump is still running 120sec.
Table 401 Standard switching thresholds
Standard
Lower switching threshold in °C 68
Upper switching threshold in °C 75
Overheating protection in °C 125

402
Thermo AC/DC 4 Functions of the heater
4.2 Functional sequence of the heater
4.2.1 Switching on
In order to switch on the heater, 24V DC respectively the
switch on signal must be connected according to the valid
wiring diagram to the AC/DC control wiring harness for
external control by an operating or control element (for
example, switch, relay, pre-selection timer) installed on
the vehicle.
This power is fed to the load contactor, the control ther-
mostat and the overheat protection (see chapter 3), which
constitute the control loop of the AC/DC control head.
The temperature guards interrupt the current path for
activating the contactor when their switching thresholds
are reached.
If all of the following three conditions are met:
1. 24V DC is applied to the external control input or the
switching contact is closed,
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 contactor is activated, the moving core attracts and
closes the main contacts.
In this way the heating cartridges connected to the
contactor are powered. Each heating cartridge now con-
verts 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 / switch on signal 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 must continue
its operation at least 120s.
4.3 Malfunctions caused by overheating /
tripping of the temperature limiter
If the heater is overheated, the temperature limiter is
tripped and the heater goes into a fault lock-out.
The circulating pump in the coolant circuit must continue
its operation at least 120s.
After cooling down and remedy the cause as well as the
inspection of the heater for possible damage, in particular
the wiring, the temperature limiter and the control ther-
mostat, the button of the temperature limiter must be reset
manually.
NOTE:
The Chapter 5 contains approaches for troubleshooting.

501
Thermo AC/DC 5 Troubleshooting
5 Troubleshooting and error correction
5.1 Allgemeines
The safety information and regulations of Chapter 1
(see 1.6 ) must be observed.
This section describes troubleshooting and error correc-
tion for Thermo AC/DC heaters.
In case of doubt functional connections can be obtained in
chapters 3and 4.
Error detection is usually limited to localizing the faulty
component.
The following malfunction causes are not taken into
account and should basically always be verified and/or a
malfunction due to these reasons should be excluded:
• Corrosion on plugs
• Loose plug connections
• Crimp failures on plugs and/or pins
• Corrosion on cable and fuses
• Cable insulation damage
ATTENTION:
Prior to replacing a fuse, troubleshooting needs to be
performed. The heater must be disconnected from the
vehicle electrical system.
A properly dimensioned fuse must be inserted (see
chapter 6wiring diagrams).
After each error correction a functional test must be per-
formed in the vehicle.
5.2 General error symptoms
he following table lists possible, general error symptoms.
Danger to life and health!
Warning!
Table 501: General error symptoms
Error symptom Possible cause
Heater can not be switched on. • Missing or insufficient supply voltage (24V)
• 24V fuses defective or not active
• Supply lead to the plug contacts of the HV control
wiring harness (24V) defective or contact not
established
• Plug of the temperature sensors not connected
• Temperature sensors defective
• HV small distribution board defective
• HVIL (Interloop) – failure (if existent)
Operation indicator does not light and the heater does
not function.
• No supply voltage
• Fuses
Heater is functional, however the operation indicator
does not light.
• Operation indicator defective or cables to the opera-
tion indicator interrupted or shorted.
ISO guard triggers because the ISO value is too low. • Insulation of one or more cables is damaged and in
contact with the electrically conductive structure of
the heater or vehicle
• Heater/heating cartridges is/are overheated
Temperature in the water circuit is too high/low • Control thermostat defective
• Diodes in LV wiring harness defective (if applicable,
heater may be hooked-up incorrectly).

502
Thermo AC/DC 5 Troubleshooting
Heater can not be switched off. • Supply voltage (24V) not switched off
• HV small distribution board defective
• Diodes in LV wiring harness defective (if applicable,
heater may be hooked-up incorrectly).
Heater does not heat. • No HV supply connected / active
• HV fuses defective or not active
• Ground fault interrupter or insulation monitoring
device (IMD) defective or not active
• HV small distribution board defective
• Heating cartridge(s) defective
No HVIL (Interloop) signal (if existent) • SC600 respective the control unit does not transmit
a HVIL signal
• HVIL contact is not established
• Hood not (correctly) mounted
• HV cable not connected
• HV control wiring harness (24V) not connected or
cable defective
Heating power too low • HV supply power too low
• Heating cartridge(s) defective
Heating power too high • HV supply power too high
•
Overheating, temperature limiter has triggered • Control thermostat defective
Heater stops as the connected heat exchangers provide
insufficient heat.
Flow rate too small, because
• Air in the heater, heat exchanger or in system
sections.
• Taps/valves (flow controllers) throttled,
contaminated, closed.
• Contaminations in the system, e.g. filters or at
bottlenecks.
• Circulating pump delivery rate insufficient
(air in pump housing).
• Insufficient frost protection.
• System resistance too high (especially high in the
cold).
• Circulating pump defective.
Heat exchanger provides not enough heat, because
• Air in the heat exchangers and/or system sections.
• Antifreeze content too high.
Approximate flow rate determination:
Heat flow [kW] according to type plate
Flow rate in [l/h] = x 860
Temperature difference ∆t in [K] or [°C]
measured on the heater between water inlet and water outlet
(e.g. using contact thermometer)
Table 501: General error symptoms
Error symptom Possible cause

503
Thermo AC/DC 5 Troubleshooting
5.3 Error symptom “Total failure of the heater“
Is there a sufficiently high control
voltage?
Check the voltage converter (see
5.8.3) or the control voltage source.
Check fuses in the control circuit and
if required remedy the fault and
replace fuse(s) (see 3.2).
Eliminate the fault cause.
Replace fuse(s)
NO
YES
Is the HV over current protection
ok?
Eliminate the fault cause.
Reset ground fault interrupter or the
ISO guard.
Is the ground fault interrupter or
the ISO guard ok?
Check acc. to the vehicle manu-
facturer‘s instructions
Check load contactor (see 5.8.4)
and replace load contactor if ne-
seccary.
Check water circuit on vehicle side.
Has the temperature limiter trigge-
red?
Eliminate the fault cause.
Reset temperature limiter.

504
Thermo AC/DC 5 Troubleshooting
5.4 Error symptom “Heating power too low or permanent operation“
Has the load contactor a sufficient-
ly high control voltage? (see Table
201)?
Establish the correct control voltage.
Eliminate the fault cause.
Replace fuse(s)..
NO
YES
Is the over current protection ok?
Establish the correct contact at all
connections at the small distribution
board.
Are all connections at the small
distribution board correct contac-
ted?
Replace control thermostat.
Check the control thermostat (see
5.8.6.1). Does the control ther-
mostat function properly?
Roughly determine water flow rate
(see 5.2). Is the water flow rate in
relation to the heating capacity too
high?
Contact Valeo customer service.
Contact Valeo customer service.

505
Thermo AC/DC 5 Troubleshooting
5.5 Error symptom „Overheating / the temperature limiter has tripped“
5.6 Error symptom „Over heating“
The upper switching threshold is exceeded, but the tem-
perature limiter does not trip.
Is the circulating pump switched on
and works properly?
Turn the circulating pump on, check
its function and the direction of rota-
tion. Replace if necessary..
NO
YES
Replace temperature limiter.
Check the temperature limiter (see
5.8.6.2). Does the temperature
limiter function properly?
Does an adequate cooling and
coolant flow exist?
Are all shut-off devices open?
Is the cooling system tight, comple-
tely filled and bled?
Is the coolant sufficiently cold-re-
sistant?
Eliminate the fault.
Replace control thermostat.
NO
YES
Check the control circuit on the
heater side for a short circuit.
Check the control thermostat (see
5.8.6.1). Does the control ther-
mostat function properly?

506
Thermo AC/DC 5 Troubleshooting
5.7 Error symptom “ISO value too low (unacceptable)“
Perform a visual inspection whether cables are damaged or squashed and rest against the housing (metal parts).
The insulation resistance must be measured at a test voltage of 1000V DC.
Wires undamaged and free? Replace damaged or pinched
cables.
Contact the vehicle manufacturer.
NO
YES
Vehicle-side insulation value
sufficient?
Replace the HV wiring harness
(see 8.7).
Insulation value up to the load con-
tactor sufficient?
Contact Valeo customer service
Insulation value after the load con-
tactor sufficient?
Contact Valeo customer service

507
Thermo AC/DC 5 Troubleshooting
5.8 Individual component tests
Individual components can be basically tested using
visual inspection or manual electrical testing.
5.8.1 General visual inspection
• Inspect components for damages (cracks, deforma-
tion, leaks, discolourations, etc.) and replace as
needed.
• Inspect plugs and cables for corrosion, contact and
crimp errors and repair as needed.
• Check plug contacts for corrosion and tight fit. Repair
as needed.
• Inspect warning placards / replace if absent or illegible
• Check that all cables and lines are sufficiently secured
with cable ties. In case of insufficient fixation or dama-
ged cable ties, retrofit or replace them.
5.8.2 Heat exchanger visual inspection
• Inspect the heat exchanger interior for damage,
corrosion, sooting and deposits.
• Inspect heat exchanger for outer damage, corrosion,
moisture, deformations, deposits, discolourations,
etc.
ATTENTION:
Soot and deposits in the heat exchanger must be
removed, as they impact the heat transfer to the
coolant.
Severe outer deformations may impact coolant flow.
5.8.3 Voltage converter check or visual
inspection
• Inspect voltage converter for damage (cracks, defor-
mation, discoloration etc.) and if required replace
small distribution board.
• Inspect wires for corrosion, contact and crimp errors
etc. and replace if required.
5.8.4 Load contactor check or visual inspection
• Inspect load contactor for damage (cracks, deforma-
tion, discoloration etc.) and if required replace small
distribution board.
• Inspect wires for corrosion, contact and crimp errors
etc. and replace if required.
5.8.5 Heating cartridges check or visual
inspection
• Inspect heating cartridge (from outside) for damage
(cracks, deformation, discoloration etc.) and replace if
required.
• Inspect wires for corrosion, contact and crimp errors
etc., replace heating cartridge if required.
5.8.6 Check of the temperature guards (control
thermostat and temperature limiter)
5.8.6.1 Control thermostat check
NOTE:
The control thermostat must be screwed in tight (by hand)
and the protective cap must be installed. The cable must
not be damaged.
Check
During the test with a digital multimeter CAT III, the control
thermostat is to be tested for continuity.
The control thermostat is connected to pins 3 and 4 of the
temperature sensor connector (see Fig. 501).
Switching temperature:
• opens at 75 ± 3°C
• closes at 68 ± 5°C
At room temperature the contact is closed. When it heats
to above the upper switching point, it is opened.
Fig. 501 Temperature sensor connector
Pin 3 & 4
Pin 1 & 2
Temperature limiter
Control thermostat