Cooling System Modification
A. COOLING SYSTEM MODIFICATIONParts Required:
(1) Kit # 1HO 198 998
Kit consists of:
Control Module 3A0 919 506
Pressure Throttle 1HO 121 135
Adapter, (optional) 535 971 566
- Bring vehicle into service area: switch ignition to off position
- Record radio code and radio pre-set stations
- Open hood and disconnect the battery ground (GND) cable
- Carefully loosen coolant expansion tank cap to relieve pressure
- Raise vehicle on hoist
- At left front of the vehicle, loosen clamp (arrow) on lower coolant hose to radiator using special VW hose clamp removal tool VAG 1921 or similar
- Cautiously disconnect hose from the radiator to drain coolant
CAUTION:
Coolant may be hot and under pressure.
- Use drain pan to collect coolant for proper disposal
IMPORTANT:
SYSTEM MUST BE COMPLETELY DRAINED
- While coolant is draining, lower vehicle to floor level being careful not to damage drain pan
- Use special VW hose clamp removal tool VAG 1921 or equivalent to remove clamp from left (outward) heater hose (inlet hose to heat exchanger) at firewall
- Disconnect hose from heat exchanger
- Insert pressure throttle (1HO 121 135) from kit (1HO 198 998) into hose approx. 25 mm (1 in.)
- Reconnect hose to heat exchanger and secure with clamp
Continue to:
- Remove (2) screws to remove coolant fan control module
- Disconnect both electrical connectors (arrows) from control module
- Discard control module
- Using a pencil, draw a line (A) through the center of both holes on the control module mounting bracket
- Draw another line (B) parallel and 13 mm (0.5 in) inward from hole center line (A)
- Draw center line (C) of each hole across new parallel line
- Center punch where both lines cross Drill (2) new 7 mm (9/32 in) holes
Hint: Drill a small pilot hole at each location before using 7 mm drill
- Check and remove all burrs on bracket around new holes
- Apply paint on all bare metal areas around new and old holes
- Install new cooling control module (3A0 919 506) from kit onto bracket at new hole location and secure with (2) screws
Note: Check for adequate clearance for opening fuse cover
- Reconnect large electrical connector to the new control module
- Check size of small connector
- If small connector is an 8 pin connector use adapter harness 535 971 566 from kit to connect to the 10 pin connector on the control module
- If small connector is a 10 pin connector, reconnect harness to control module; return the adapter 535 971 566 from kit to parts for inventory - no value
- Raise vehicle on hoist
- Reconnect lower radiator hose to radiator and secure with clamp
- Remove drain pan and properly dispose of old coolant
- Lower vehicle, refill cooling system with new coolant: use antifreeze part number ZVW 237 105 and mix 50/50 with water prior to filling
Note:
System must be filled only with VW- supplied antifreeze, part number ZVW 237 105
- Reconnect battery ground (GND) cable
- Start engine to obtain normal operating temperature (radiator fan comes on)
- Add coolant as required to maintain correct level
- Activate radio with radio code and set radio pre-set stations
- Reset clock
- If vehicle has an automatic transmission, set basic settings
- Close hood