1990 VOLKSWAGEN CORRADO heater

GENERAL COOLING SYSTEM SERVICING
Article Text
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:45PM
ARTICLE BEGINNING
GENERAL INFORMATION
General Cooling System Servicing
* PLEASE READ THIS FIRST *
The following article is for general information only.
Information may not apply to all years, makes and models. See specific
article in the ENGINE COOLING section.
DESCRIPTION
The basic liquid cooling system consists of a radiator, water
pump, thermostat, electric or belt-driven cooling fan, pressure cap,
heater, and various connecting hoses and cooling passages in the block
and cylinder head.
MAINTENANCE
DRAINING
Remove radiator cap and open heater control valve to maximum
heat position. Open drain cocks or remove plugs in bottom of radiator
and engine block. In-line engines usually have one plug or drain cock,
while "V" type engines will have 2, one in each bank of cylinders.
CLEANING
A good cleaning compound removes most rust and scale. Follow
manufacturer's instructions in the use of cleaner. If considerable
rust and scale has to be removed, cooling system should be flushed.
Clean radiator air passages with compressed air.
FLUSHING
CAUTION: Some manufacturers use an aluminum and plastic radiator.
Flushing solution must be compatible with aluminum.
Back Flushing
Back flushing is an effective means of removing cooling
system rust and scale. The radiator, engine and heater core should be
flushed separately.
Radiator
To flush radiator, connect flushing gun to water outlet of
radiator and disconnect water inlet hose. To prevent flooding engine,
use a hose connected to radiator inlet. Use air in short bursts to
prevent damage to radiator. Continue flushing until water runs clear.
Engine

GENERAL COOLING SYSTEM SERVICING
Article Text (p. 2)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:45PM
To flush engine, remove thermostat and replace housing.
Connect flushing gun to water outlet of engine. Flush using short air
bursts until water runs clean.
Heater Core
Flush heater core as described for radiator. Ensure heater
control valve is set to maximum heat position before flushing heater.
REFILLING
To prevent air from being trapped in engine block, engine
should be running when refilling cooling system. After system is full,
continue running engine until thermostat is open, then recheck fill
level. Do not overfill system.
TESTING
THERMOSTAT
1) Visually inspect thermostat for corrosion and proper
sealing of valve and seat. If okay, suspend thermostat and thermometer
in a 50/50 mixture of coolant and water. See Fig. 1. Do not allow
thermostat or thermometer to touch bottom of container. Heat water
until thermostat just begins to open.
2) Read temperature on thermometer. This is the initial
opening temperature and should be within specification. Continue
heating water until thermostat is fully open and note temperature.
This is the fully opened temperature. If either reading is not to
specification, replace thermostat.Fig. 1: Testing Thermostat in Anti-Freeze/Water Solution
PRESSURE TESTING
A pressure tester is used to check both radiator cap and
complete cooling system. Test components as follows, following tool

HEATER SYSTEM
Article Text
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:45PM
ARTICLE BEGINNING
1990 HEATER SYSTEMS
Volkswagen
Cabriolet, Corrado, Fox, Golf GL, GTI, Jetta,
Jetta GLi, Vanagon
WARNING: To avoid accidental air bag deployment, see AIR BAG
DEACTIVATION SERVICING PRECAUTIONS in this article.
DESCRIPTION
The heater is a water-valve type that combines heating,
defrosting and ventilation into one unit. Controls include fan control
knob and air distribution and temperature control levers. Blower fan
provides 3 speeds.
NOTE: Vanagon heater system information is not available from
manufacturer. For wiring diagram information, see WIRING
DIAGRAMS at end of this article.
OPERATION
When air distribution lever (upper lever) is in the center
stop position and lower temperature control lever is to the far left,
no air enters vehicle. As air distribution lever is moved to the left,
air is directed to floor vents. As distribution lever is moved to the
right, air is directed to defroster vents.
As heater lever (lower lever) is moved to the right, heater
turns on and heat output is increased. As the fan control knob is
turned to the right, the fan turns on and can be switched across its 3
speeds.
AIR BAG DEACTIVATION SERVICING PRECAUTIONS
WARNING: Some models are equipped with driver's side air bag
restraint system. Air bag-equipped vehicles have AIRBAG
stamped on the steering wheel horn pad. Air bag system
capacitor maintains a voltage charge sufficient to cause air
bag deployment for up to 20 MINUTES after ignition switch is
turned off and battery is disconnected.
DISABLING SYSTEM
Ensure ignition switch is OFF. Disconnect negative battery
cable and insulate terminal. Wait at least 20 MINUTES before
proceeding with repairs.
SYSTEM FUNCTIONAL CHECK

HEATER SYSTEM
Article Text (p. 2)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:45PM
When all service work is completed, reconnect negative
battery cable. Turn ignition on. Ensure the left turn indicator light
comes on for about 5 seconds and then goes out. If light does not come
on for about 5 seconds and then go out, air bag system needs to be
serviced.
TEMPERATURE CONTROL LEVER ADJUSTMENTS
Move temperature control lever to extreme left position.
Place heater control valve lever in closed position. Secure cable with
a clip.Fig. 1: Exploded View of Heater System (Cabriolet & Fox)
Courtesy of Volkswagen United States, Inc.

HEATER SYSTEM
Article Text (p. 3)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:45PMFig. 2: Exploded View of Heater System (Golf GL, GTI, Jetta &
Jetta GLi)
Courtesy of Volkswagen United States, Inc.

HEATER SYSTEM
Article Text (p. 4)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:45PMFig. 3: Exploded View of Heater System (Vanagon)
Courtesy of Volkswagen United States, Inc.
HEATER ASSEMBLY R & I
REMOVAL (CABRIOLET & FOX)
1) Drain coolant from radiator. Loosen clamps and remove
heater core hoses. Disconnect battery ground cable. Pull heater
control knobs off. Remove trim plate and underdash access panels.
2) Disconnect wiring from blower motor, and remove cable from
temperature control lever. Pry spring clamp off with screwdriver and
separate heater assembly halves. Remove heater core and blower motor.
INSTALLATION
To install, insert blower motor and heater core into right
half of housing. Position left half and install spring clips. To
complete installation, reverse removal procedure.
REMOVAL (GOLF GL, GTI, JETTA & JETTA GLI)
1) Disconnect negative battery cable. Drain coolant from
radiator. Remove steering wheel. Remove lower left instrument panel

HEATER SYSTEM
Article Text (p. 5)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:45PM
retaining screws. Remove lower left instrument panel. Remove lower
right instrument panel tray retaining screws.
2) Remove lower right instrument panel. Remove gearshift
lever knob. Remove gearshift lever boot. Remove center console
retaining screws. Slide center console rearward. Disconnect electrical
connectors attached to center console. Remove center console.
3) Remove temperature control knobs. Remove trim plate.
Remove radio. Remove switches from instrument panel. Remove instrument
panel trim plate retaining screws. Remove instrument panel trim plate.
Remove instrument cluster retaining screws. Remove instrument cluster.
4) Disconnect speedometer cable, electrical connectors and
vacuum hoses from instrument cluster. Remove speaker grilles. Remove
air outlet grilles from housings. Remove housing retaining screws.
Remove air outlet housings. Remove instrument panel mounting nuts and
screws.
5) Remove instrument panel. Disconnect heater hoses from
heater core. Remove heater assembly mounting bolts and nuts. Remove
all attaching ducts. Disconnect cables from heater assembly. Remove
heater assembly.
INSTALLATION
Reverse removal procedure for installation. Fill radiator
with coolant and start engine. Ensure heater control is in warm
position to purge air from heater core.
WIRING DIAGRAMSFig. 4: Heater System Wiring Diagram (Cabriolet)Fig. 5: Heater System Wiring Diagram (Corrado)

HEATER SYSTEM
Article Text (p. 6)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:45PMFig. 6: Heater System Wiring Diagram (Fox)Fig. 7: Heater System Wiring Diagram (Golf GL, GTI, Jetta & Jetta
GLi)Fig. 8: Fresh Air Blower Motor Wiring Diagram (Vanagon)Fig. 9: Warm Air Blower Motor Wiring Diagram (Vanagon)