Volkswagen Polo Service & Repair Manual: Electrical Components Not on Refrigerant Circuit

A/C Compressor Regulator Valve -N280

  Note For switching pressures, removing and installing switches and switch arrangement and version, see vehicle-specific refrigerant circuit. ...

A/C Programmer -J127

This programmer switches the refrigerant flow direction through the second evaporator if the temperature on the cooling fins on the second evaporator lowers to the fr ...

Other materials:

4-Pin Heated Oxygen Sensor (HO2S), Removing and Installing
  Note Do not repair the heated oxygen sensor wires. Repairing may result in malfunctions. Use the faulty sensor as a guide for installing all of the accompanying attachments, cable ties or marking bands. ...

Introduction
The purpose of this Repair Manual is to provide foremen and mechanics with the basic knowledge needed to ensure expert working.   Note Expert knowledge is achieved by one who has taken part successfully in instructiona ...

Changing engine oil
First read and observe the introductory information and safety warningsThe engine oil must be changed regularly in accordance with the data given in the service schedule. The engine oil and filter should always be changed, and used oil disposed of, by a qualified workshop due to the special ...