Volkswagen Workshop Service and Repair Manuals

Special tools, workshop equipment, testers, measuring instruments and auxiliary items required

• ◆ V.A.G 1526 A Hand multimeter

• ◆ V.A.G 1594 A Adapter set

Notes:

• ◆ Remove Thermotronic controls for all tests.
• ◆ Use leads from adapter set V.A.G 1594 A to connect up testers.
• ◆ Numbers 18 to 28 on the trim are references for the inside temperature. They are not test data.

• Connector, 8-pin, on instrument panel wiring loom
• Connector, 8-pin, on electronically controlled heater wiring loom.

• Temperature sensor - fresh air intake duct -G89-
• ◆ Fitting location: in fresh air intake duct behind shelf passenger side.
• ◆ Check: at 25 °C, resistance should be 10 kω. Resistance decreases with increasing temperature.
• ◆ Removing and installing: remove cover, right, below dash panel. Turn sensor and pull out of fitting.
• Connector -T5-
• Thermotronic control unit -J214-
• ◆ Renewing=>Fig.3

• Fresh air fan series resistor with overheating fuse -N24-
• ◆ Removing =>Fig.2
• Connector -T4-
• Connector -T2e-
• ◆ Connects bulb for fresh air control lighting
• Fresh air and heating controls
• ◆ The controls are identical to those on the heater system without electronic regulation. The Thermotronic controls also have the control unit -J214- fitted.
• Connector -T6a-
• ◆ On fresh air and heater controls

• Temperature sensor - dash panel -G56- and blower for temperature sensor -V42-
• ◆ Checking temperature sensor: at 25°C, resistance should be 3 kω. Resistance decreases with increasing temperature (measure between chambers 1 and 3).
• ◆ Removing => Fig.1
• Temperature flap control motor -V68-
• ◆ Check end position of control motor when installed =>Fig.4
• ◆ Check resistance of control motor potentiometer -G92- when installed =>Fig.5

Fig.1     → Removing dash panel temperature sensor -G56- and temperature sensor blower -V42-

Note:

Obtain code for radio with anti-theft coding before disconnecting battery.

• ‒ Remove radio
• ‒ Remove central vent housing

•      1 -     Temperature blower sensor -V42-
•      2 -     Dash panel temperature sensor -G56-
•      3 -     Central vent housing
•      4 -     Grille

→ Fig.2     Removing fresh air blower series resistor and overheating fuse -N24-

• ‒ Remove Phillips screw
• ‒ Press in direction of arrows to release catch.

Fig.3     → Renewing Thermotronic control unit -J214-

• ‒ Turn Thermotronic centre rotary control -2- past the resistance to the blue end point.
• ‒ Turn control unit pinion -1- until the marking and the pin are aligned.
• ‒ Assemble control unit -1- and controls -2-.

Fig.4     → Checking end position of control motor -V68- when installed

• ‒ Pull 5-pin connector off control unit -J214-
• ‒ Connect cables from adapter set V.A.G 1594 A to chambers 4 and 5.
• ‒ Connect to 12 V supply. Direction of rotation can be changed by reversing polarity of voltage supply.
• ‒ Move temperature flap -2- with control motor -1- from heater end position -4- to fresh air end position -3-.
• ‒ Check whether the temperature flap lever -2- reaches the stop when at the end position. If necessary, adjust length of connecting rod -1- with temperature flap -2- on stop.

Note:

If the connecting rod has been loosened, the rotary control is to be turned to the blue mark "cold" and the temperature flap lever must be pretensioned by pressing lightly towards cold and secured (4 clips).

Fig.5     → Checking resistance of potentiometer -G92- for control motor -V68- when installed

• ‒ Pull 5-pin connector off control unit -J214-
• ‒ Connect cables from adapter set V.A.G 1594 A to chambers 4 and 5.
• ‒ Connect to 12 V supply. Direction of rotation can be changed by reversing polarity of voltage supply.
• ‒ Measure resistance between chambers 1 and 2 using hand multimeter V.A.G 1526 A:

• Fresh air end position -2-, Specification: 2 kω ±20%
• Heating end position -1-, Specification: approx. 0,2 kω