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operational manual of PTC Coolant heater
Source: | Author:Admin | Published time: 2021-03-23 | 6202 Views | Share:

PTC coolant heater  operation  manual

Applicable air conditioning/battery warming

Safety precautions (read before use)

Warning! Improper operation of the following items may cause the vehicle to stop. Always follow the safety precautions during use to prevent accidents and potential dangers.

Whenever heater is abnormal or burnt smell is found, please cut off the high voltage power supply immediately

only in rated DC voltage range

 heater must be fixed tightly

configure a high-voltage relay for the PTC, and disconnect the PTC high-voltage supply when serious fault appears

 configure a high-voltage fuse for the PTC. When the PTC heating core is short-circuited and the IGBT breakdown fault occurs at the same time, an external fuse fusing protection is required!

 high voltage precharge is recommended

A reliable grounding wire must be used, otherwise there is a risk of leakage and static electricity

 The heater has high-voltage electricity when heater is working, and high-voltage connectors can not be plugged in and out

When fixing or repairing, heater must be power off.

 If WPTC is not started normally, there may be a risk of leakage. You need to find out the fault before running

 Non-professional maintenance personnel should not repair, maintain, disassemble or modify the heater without authorization


PTC coolant heater is developed on basis of the air-heating PTC heater. The heating medium is changed from air to liquid; it is a new energy vehicle air conditioner/battery heating performance part In the long-term production and operation, We have made relevant research and summarization on the common faults and maintenance methods of PTC coolant heater. This manual is specially compiled for use and reference by various automobile manufacturers and air-conditioning manufacturers.

Due to product upgrades or improvements, the purchased product is not completely consistent with this maintenance view. In order to ensure the correct use of the product, please contact our company in time.


Chapter 1.main structure and performance

Chapter 2:installation precautions

Chapter 3.how to use

Chapter 4 Diagnosis,inspection and maintenance

Chapter 5maintenance

Chapter 1:main structure and performance

■PTC coolant heater (as above picture)

1upper and lower lid

The heating shell is composed of upper and lower covers, which are used to protect the heating core and control board inside the shell. The upper and lower covers are made of PPA material, which has high strength, high rigidity, dimensional stability, low warpage and good chemical corrosion resistance.


high and low voltage connectors are installed with flanges. The definition of high and low voltage connectors is shown in the figure below:

3Control board

Using IGBT as a power drive element, controlled by MCU program, using CAN bus control method to control the power of PTC heater, with soft-start function, high and low voltage undervoltage protection, low voltage reverse connection protection (high voltage does not have reverse connection protection function), with Over-voltage and under-voltage protection automatically stops the output function, and has multiple self-protection functions such as over-temperature and over-current.

4.heating body

The PTC heater is composed of a combination of a PTC core and a water tank, which can quickly heat the liquid. The water tank is used as a heat dissipation component to transfer the heat generated by the heating core to the liquid inside the flat tube of the water tank, and due to the characteristics of the PTC chip itself, the heating core has a self-protection function against dry burning;PTC

■WPTC has IP67 protection grade. The low voltage adopts DC12V power supply, the high voltage rated power supply voltage is DC380V, the rated power is 6KW, and the high voltage interlock (HVIL) function is provided. Use CAN signal to control PTC output power.

Chapter 2 Installation precautions

In order to ensure the maximum energy efficiency of plumbing PTC, pay attention to the following matters when installing

1. The highest point of PTC should be lower than the expansion tank;

2. The water pump should not be higher than PTC;

3. The PTC should be installed after the water pump and before the heater core;

4. Pay attention to the direction of PTC inlet and outlet;

5. Before the PTC works for the first time or after repairing the piping components, the water pump should be operated first, and the exhaust gas should be confirmed before powering on the PTC.

6Before powering on, pay attention to the installation and the reliable connection of the connectors (the main high voltage cannot be reversed, otherwise the control will fail, and the control board will be damaged for more than 1 minute);

7The grounding wire is connected reliably to prevent high voltage leakage;

8Please fix the heater with M6 screw

8After unpacking, please be sure to check whether there is appearance damage caused by transportation. Damage caused by improper installation and use (including use and installation conditions outside the scope of the specification) is not covered by the warranty.

Chapter 3.how to use

 1First plug HV and LV connectors

2first power on LV then HV

3Communication with PTC

4input requirements, heater beginS to work

5When stopping using heater, fist power off High voltage, then Low voltage

◆After the heater is tightly fixed, make sure water pump works,coolant is filled into water tank, and there is no leakage at the detection interface before powering on

Chapter 4. Common fault diagnosis, inspection and maintenance




HV does not work

HV connector not plugged in or not  tightly

Check  the wiring sequence of the low voltage connector

LV connector not plugged in or not  tightly

Check  the wiring sequence of the low voltage connector

Insulation resistance is low

Replace  PTC heater

Open circuit of HV interlock

Check  whether the high and low voltage connector interlock circuit is in good  contact

Not heating

HV connector defected or not plugged  tightly

Check  whether the low voltage connector is in good contact

LV connector defected or not plugged  tightly

Check  whether the low voltage connector is in good contact

LV connector wire wrong connecting

Check  the wiring sequence of the low voltage connector

HV out of range

Restore  HV value in scope

Heater sensor fault

Replace  PTC heater

CAN signal not in scope of protocol

Check  if message signal is correct ot not

CAN signal wire short circuit tp  ground

Check  whether the low-voltage connector signal terminal pin is skewed and  short-circuited

CAN signal wire short circuit to power  supply

Check  whether the low-voltage connector signal terminal pin is skewed and  short-circuited

LV out of scope of voltage range

Check  voltage

HV out of scope of voltagerange

Check  voltage

Inner sensor fault

Replace  PTC heater

Inner  control circuit fault

Replace  PTC heater

Slow heating

Inlet Coolant temperature is too low  and startup slowly

High flow rate and start upslowly

Adjust  flow rate

CAN power request low

Adjust  CAN request power

Low voltage of HV and startup slowly

Adjust  voltage

Partial  failure of internal control circuit

Replace  heater

Direct heating without control message

HV reverse connecting

Change  connecting in one minute

Partial  failure of internal control circuit

Replace  heater

Auto power off and restart

Over current

Over temp

Reduce  request power  or increase flow rate

PTC dry burn

Check  if water pump is working well

Lower voltage of LV

Adjust  voltage

Over voltage of HV

Adjust  voltage

Lower voltage of HV

Adjust  voltage

Partial failure of internal control  circuit

Replace  heater

External fuse blown

The heating core is short-circuited  and the control circuit protection fails

Replace  heater

The high voltage positive and negative  poles are short-circuited to the shell

Replace  heater

Chapter 4. Maintenance

1、 Read carefully this manual

2、 Check input voltage if it is in scope or not,terminal definition is correct or not, connecting is correct or not

3、 Check screwing is tight or not.