VOLKSWAGEN CORRADO 1990 Repair Manual

A/C SYSTEM GENERAL DIAGNOSTIC PROCEDURES
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 09:41PM
moisture or restriction.
Check sensing bulb.
* STV Dry & cool to touch Frosty or warm - Check
gauge readings for valve
malfunction.
* Evaporator Dry & cold to touch Freezing or warm - Check
expansion valve, STV or
thermo switch.ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄGauge Readings Gauge Readings are:
* High Side Gauge See Pressure Chart Above or below normal -
See A/C Diagnosis.
* Low Side Gauge See Pressure Chart Above or below normal -
See A/C Diagnosis.
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄFig. 1: Ambient Temperature/Pressure A/C Chart

A/C SYSTEM GENERAL DIAGNOSTIC PROCEDURES
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 09:41PMFig. 2: Evaporator Temperature/Pressure A/C Chart
AIR CONDITIONING DIAGNOSIS WITH GAUGES FOR SYSTEMS WITH
INSUFFICIENT OR NO COOLING TABLEÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄLow Side High Side Other Symptoms (1) Diagnosis
Gauge Gauge
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄNORMAL NORMAL No or few bubbles in sight Some Air and
glass. High side gauge may Moisture in
go high. Low side gauge System
does not fluctuate with
compressor on/off cycle.
NORMAL NORMAL Cools okay in morning but Excessive
not during hot part of day. Moisture in
Bubbles in sight glass. System
Discharge air warm when low
side gauge drops into vacuum.
NORMAL NORMAL Thermostatic switch system Defective
only - compressor cycles off Thermostatic

A/C SYSTEM GENERAL DIAGNOSTIC PROCEDURES
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 09:41PM
and on too rapidly. Switch
NORMAL NORMAL Cycling clutch systems only - Misadjusted
to compressor doesn't turn on Thermostatic
HIGH soon enough. Discharge air Switch or
becomes warm as low side Defective
pressure rises. Pressure
Sensing Switch
LOW LOW Bubbles in sight glass. Low R-12
Outlet air slightly cool. Charge
LOW LOW Sight glass clear. Outlet Excessively
air very warm. Low R-12
Charge
LOW LOW Outlet air slightly cool. Expansion
Sweating or frost at Valve Stuck
expansion valve. Closed Screen
Plugged or
Sensing Bulb
Malfunction
LOW LOW Outlet air slightly cool. Restriction
High side line cool to touch. on High Side
Sweating or frost on high
side.
LOW HIGH Evaporator outlet pipe cold. STV Stuck
Low side goes into vacuum Open
when blower is disconnected.
HIGH LOW Evaporator outlet pipe warm. STV Stuck
Outlet air warm. Closed
HIGH LOW Noise from compressor. Compressor
Malfunction
HIGH HIGH Outlet air warm. Liquid Compressor
line very hot. Bubbles in Malfunction
sight glass. or R-12
Overcharge
HIGH HIGH Outlet air slightly cool. Large Amount
Bubbles in sight glass. of Air and
Moisture in
System
HIGH HIGH Outlet air warm. Evaporator Expansion
outlet sweating and frost. Valve
Stuck Open
(1) - If equipped with a low refrigerant charge protection system,
compressor operation may have stopped.ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄEND OF ARTICLE

A/C SYSTEM PRECAUTIONS
Article Text
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:41PM
ARTICLE BEGINNING
AIR CONDITIONING & HEAT
A/C System Precautions
* PLEASE READ THIS FIRST *
CAUTION: When discharging air conditioning system, use only approved
refrigerant recovery/recycling equipment. Make every attempt
to avoid discharging refrigerant into the atmosphere.
BEFORE OPENING THE SYSTEM
Before disconnecting any lines or fittings, the system must
be completely discharged using approved refrigerant recovery/recycling
equipment.
DISCHARGING A/C SYSTEM
NOTE: Recent findings by the EPA indicate that R-11, R-12 and R-113
are harmful to the Earths' protective Ozone layer. Make every
attempt possible, to avoid discharging R-11, R-12 or R-113
into the atmosphere.
1) Remove service valve caps and install gauges. For high
side gauge hose, Adapter (D81L-19703-A) must be used to connect to
high side service valve.
2) Place open end of center hose in garage exhaust outlet or
in a well ventilated area. Slightly open low side gauge valve and let
refrigerant escape slowly without loosing refrigerant oil.
3) When system is nearly discharged, using approved
refrigerant recovery/recycling equipment, open high side gauge valve
to release any pressure trapped in compressor. Close valves
immediately after discharging to prevent entry of moisture.
DISCONNECTING LINES & FITTINGS
1) After system is discharged, using approved refrigerant
recovery/recycling equipment, carefully clean entire area around
coupling nut to prevent dirt entering system. Always use two wrenches
to avoid twisting or distorting lines and fittings (hold fitting with
one wrench while loosening coupling nut with second wrench).
2) Cap or plug all LINES and FITTINGS immediately to prevent
entry of air and moisture into system. Do not remove these caps until
connections are being made.
COMPONENT REPLACEMENT
When components are replaced, system oil level must be
adjusted. Add refrigeration oil to replacement component. See

A/C SYSTEM PRECAUTIONS
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 09:41PM
Compressor oil Check article, as well as, Component Oil Replacement
Quantities" chart under "A/C SYSTEM SPECS" article in this section.
USING R-12 REFRIGERANT - SAFETY PRECAUTIONS
1) Always work in a well-ventilated, clean area. Refrigerant
(R-12) is heavier than oxygen, and will displace oxygen in a confined
area. Always wear eye protection when working around air conditioning
systems and R-12. The system's high pressure can cause severe injury
to eyes and skin if a hose were to burst. R-12 evaporates quickly
when exposed to atmosphere, freezing anything it contacts.
2) Use care when handling refrigerant containers. DO NOT drop
or strike containers or expose refrigerant containers to excessive
heat. Containers must never be heated more than 125øF (52øC). Never
expose R-12 directly to open flame.
CAUTION: When R-12 is exposed to an open flame, drawn into a running
engine, or detected with a Halide (propane) leak tester,
poisonous phosgene gas is formed. Keep work areas ventilated
and avoid running engines near work area.
USING INDIVIDUAL R-12 CANS
Disposable refrigerant cans (referred to as one pound cans)
have a flat type seal or a screw type seal, and proper can tap must be
used for each type. Be sure sealing gasket on can tap is in good
condition. A proper safety can tap will prevent refrigerant from
flowing back into open can, as tap has a one-way flow control.
NOTE: Recent findings by the EPA indicate that refrigerant is
harmful to the Earth's protective Ozone layer. When
discharging refrigerant avoid allowing refrigerant to enter
the atmosphere. Refrigerant recovery system should be used
when discharging the system.
MULTI-CAN DISPENSING VALVES
A multi-can dispensing valve allows attachment of several
cans of refrigerant, and is a good substitute when a bulk container is
not available. Cans are installed onto each leg of multi-can
dispensing valve in the same manner as the individual cans, and each
leg has its own can tap.
CAN TAP INSTALLATION FLAT TYPE SEAL CANS
On cam-lock or one-piece can taps, first turn the handle
outward to the fully open position. Securely engage locking lugs over
the can flange, and lock them in place by turning cam lock or locking
nut. Screw tap assembly into adapter so sealing gasket is fully seated
against the can top. Turn tap inward to pierce the can and close the
tap. DO NOT open tap until ready to purge the service hose or dispense

A/C SYSTEM PRECAUTIONS
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 09:41PM
refrigerant into the system.
On 2-piece can taps, be certain tap handle is turned fully
inward to the closed position. Check that locking base is turned to
its outer limit. Securely engage locking lugs over the can flange.
Turn entire tap assembly (without disturbing the closed setting)
downward into the locking base to pierce the can. DO NOT open tap
until ready to dispense into system.
SCREW TYPE SEAL CANS
Ensure can tap is fully closed. Screw refrigerant can into
can tap fitting until tight. This will pierce the can. Connect tap to
center hose on manifold gauge set. DO NOT open tap until ready to
dispense R-12 into system.
WARNING: DO NOT open high side hand valve while air conditioning
system is in operation. This high pressure could rupture can
or fitting at safety can valve, resulting in damage and
personal injury.
CONNECTING LINES & FITTINGS
A new "O" ring should be used in all instances when
connecting lines and fittings (dip "O" ring in clean refrigeration oil
and make certain it is not twisted during installation). Always use
two wrenches to avoid twisting or distorting lines and fittings,
tighten coupling nuts securely.
PLACING SYSTEM IN OPERATION
After component replacement and/or system servicing has been
completed and all connections have been made, proceed as follows:
1) Evacuate the system using a vacuum pump.
2) Charge the system with new R-12 (refrigerant) according to
each individual vehicle as outlined in the GENERAL SERVICING article.
Also see Refrigerant Capacity in this Section.
3) Leak test the system, with particular attention to all new
connections and components.
4) Make a performance test of the system. Never assume that a
recharging has automatically corrected a problem.
COMPRESSOR REMOVAL INFORMATION - ISOLATION METHOD
On systems which have compressors equipped with stem-type
service valves (Tecumseh), it is possible to isolate the compressor
for removal.
Isolating
Turn both high and low pressure manual valves to extreme
clockwise (front seat) position. Loosen cap on high pressure manual

A/C SYSTEM PRECAUTIONS
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 09:41PM
valve connection to compressor and allow gas to escape until
compressor is relieved of pressure.
COMPRESSOR REMOVAL INFORMATION - DISCHARGE METHOD
This procedure is to be used on vehicles which have
compressor equipped with Schrader service valves. In these cases, the
compressor cannot be isolated and the system must be discharged, using
approved refrigerant recovery/recycling equipment, prior to compressor
removal.
END OF ARTICLE

A/C-HEATER SYSTEM - MANUAL
Article Text
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:41PM
ARTICLE BEGINNING
1990 MANUAL A/C-HEATER SYSTEMS
Volkswagen
Cabriolet, Corrado, Fox, Golf GL, GTI,
Jetta, Jetta GLi, Vanagon
* PLEASE READ THIS FIRST *
CAUTION: When discharging air conditioning system, use only approved
refrigerant recovery/recycling equipment. Make every attempt
to avoid discharging refrigerant into the atmosphere.
AIR BAG WARNING
WARNING: To avoid accidental air bag deployment on Cabriolet, see AIR
BAG DEACTIVATION under SERVICING PRECAUTIONS in this article.
DESCRIPTION
The Volkswagen air conditioning system is a cycling clutch
type. The compressor is cycled on and off by a thermostatic switch to
maintain constant cooling rate.
Other components include an evaporator, expansion valve,
receiver-drier, control panel, condenser, high-pressure switch and a
low-pressure switch. On Vanagon, the A/C thermostat can be found on
left rear pillar, above relay panel assembly (behind trim panel).
The control panel includes a pair of levers and a fan control
switch. The upper lever operates air distribution flap. The lower
lever controls temperature selection. The rotary fan control switch
controls fan speed selection.
OPERATION
SYSTEM CONTROLS
Air Distribution Lever
When in A/C position, cool air is routed to registers and
side air vents. In BI-LEVEL position, cool air is routed to floor
vents as well as registers and side air vents. In HEAT position, warm
air is routed to windshield vents, side window nozzles and floor and
center registers. In DEFOG position, warm air is routed to windshield
vents, side window nozzles and side registers.
Fan Control Knob
The fan control knob controls airflow. As knob is turned
clockwise, air intake opens and fan operates, increasing speed as knob
is moved to extreme right position.

A/C-HEATER SYSTEM - MANUAL
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 09:41PM
Temperature Control Lever
The temperature control lever controls heating and cooling.
When moved to the left, lever turns compressor on. When moved to the
right, a heater water valve is opened, supplying coolant to heater
core.
HIGH-PRESSURE SWITCH
High-pressure switch shuts compressor off if high pressure
reaches 210 psi (14.8 kg/cmý). High-pressure switch will reset when
pressure decreases to 174 psi (12.2 kg/cm
ý).
LOW-PRESSURE SWITCH
Low-pressure switch cuts off system operation when there is
abnormally low pressure in system. This protects the compressor when
there is not enough R-12 in system. Low-pressure switch shuts
compressor off at 26 psi (1.8 kg/cm
ý).
THERMOSWITCH
Thermoswitch shuts compressor off if coolant temperature
rises above 248
øF (120øC).Fig. 1: Locating A/C Components (Vanagon)
Courtesy of Volkswagen United States, Inc.

A/C-HEATER SYSTEM - MANUAL
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 09:41PMFig. 2: Exploded View of Manual A/C-Heater System Components
(Cabriolet)
Courtesy of Volkswagen United States, Inc.