Volkswagen Corrado (1993 year). Manual - part 95

A/C-HEATER SYSTEM - MANUAL 

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).

         THERMOSWITCH

         Thermoswitch shuts compressor off if coolant temperature is
greater than 248

ø

F (120

ø

C).

         ADJUSTMENTS

         AIR DISTRIBUTION CONTROL

         1) Move air distribution control knob to defrost position.
Connect 3-foot long control cable to footwell/defrost flap lever. Push
flap lever toward cable and secure cable sheath with retainer clip.
         2) Move air distribution control knob to panel (vent)
position. Connect 2-foot long control cable to center flap lever. Push
flap lever away from cable and secure cable sheath with retainer clip.

         TEMPERATURE CONTROL

         Move temperature knob to full cool position. Connect
temperature control cable (Blue sheath) to temperature flap lever.
Push flap lever away from cable and secure cable sheath with retainer
clip.

         TROUBLE SHOOTING

         NO COOLING

         1) Ensure blower fan motor operates in all 4 speeds. Ensure
air duct closes off outside air and heater water valve is closed.
Clean condenser.
         2) Inspect receiver-drier pressure seal. If seal is good, go
to step 3). If seal is broken, replace seal. Evacuate and recharge
system. If system cools properly, testing is complete. If system does
not cool, connect pressure gauges.
         3) Adjust engine speed to 2500 RPM. Set controls for maximum
cooling and high fan. Insert thermometer in left air duct and close
all other ducts. With vehicle in shade, close windows and doors and
connect pressure gauges. Operate system for 10 minutes.
         4) If fan does not operate, replace pressure switch. Ensure
system is okay. If fan does come on, turn engine off, and check for
condenser obstructions and blocked airflow.
         5) Turn air conditioner on and off with temperature control.
Ensure compressor clutch engages. Push lever to extreme right position
and back again. A click should be heard from compressor clutch. If a
click is not heard, check for voltage at clutch coil wire with switch
on. If voltage is present, replace clutch coil. If voltage is not
present, check wiring or replace thermostatic switch.
         6) If compressor clutch operates, check gauge readings. If

A/C-HEATER SYSTEM - MANUAL 

         INSUFFICIENT COOLING

         1) Ensure blower fan motor operates at all 4 speeds. Ensure
air duct closes off outside air intake and heater water valve is
closed. Clean condenser.
         2) Adjust engine speed to 2500 RPM. Set controls for maximum
cooling and high fan. Insert thermometer in left air duct and close
all other ducts. With vehicle in shade, close windows and doors and
connect pressure gauges. Operate system for 10 minutes.
         3) If both gauges read too high, replace expansion valve. If
both gauges read low, locate leak and recharge system. If both gauge
readings are normal, go to next step. If high side is too high and
suction side is normal, go to step 5). If high side is too low and
suction side is too high, go to step 6). If high side is normal and
suction side is too low, go to step 7).
         4) Turn compressor off and observe gauges. If readings
equalize in 30 seconds, replace compressor. If readings take longer to
equalize, ensure capillary tube installed length is 13" (330 mm).
         5) If capillary tube installation is correct, run system at
maximum cooling for 15 minutes. If thermometer indicates temperature
is less than 36

ø

F (2

ø

C) when compressor is turned off, or temperature

is greater than 48

ø

F (9

ø

C) with compressor on, replace thermostatic

switch.
         6) Check condenser fins and clean or straighten. If operation
is still not correct, discharge system until bubbles appear in sight
glass. Recharge system until bubbles disappear, and recheck pressures.
If operation is still incorrect, locate leaks and tighten fittings.
Discharge A/C system using approved refrigerant recovery/recycling
equipment. Evacuate system to remove all air and recharge system.
         7) Check for bubbles at sight glass. If bubbles are present,
repair leaks and recharge system. If no bubbles are present, check
condenser-to-expansion valve line for kinks and repair if necessary.
Check line (from condenser to expansion valve) for restrictions by
feeling line for cold spots. If there are no cold spots, replace
expansion valve.
         8) If cold spot is felt, remove and flush out lines and
condenser. Check for bubbles at sight glass. If there are no bubbles
present, replace compressor. If bubbles are present, check for leaks.
Repair and recharge system.

         INTERMITTENT COOLING

         1) Ensure blower fan motor operates in all 4 speeds. Ensure
air duct closes off outside air and heater water valve is closed.
Clean condenser.
         2) Adjust engine speed to 2500 RPM. Set controls for maximum
cooling and high fan. Insert thermometer in left air duct and close
all other ducts. With vehicle in shade, close windows and doors and

A/C-HEATER SYSTEM - MANUAL 

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). If low pressure gauge

reading is incorrect, place hands around expansion valve to warm
valve. If pressure rises, moisture is present in system. Discharge A/C
system using approved refrigerant recovery/recycling equipment.
Evacuate and recharge system. If pressure does not rise, go to next
step.
         4) Check temperature on thermometer when thermostatic switch
turns compressor off. If temperature is 39

ø

F (4

ø

C), system is okay. If

temperature is lower than 39

ø

F (4

ø

C), ensure capillary tube installed

length is 13" (330 mm). If capillary tube installation is correct,
replace thermostatic switch.

         TESTING

         A/C SYSTEM PERFORMANCE

         1) Park vehicle out of direct sunlight. Start engine and
operate engine at 2500 RPM. Set A/C controls to outside air, panel
(vent) mode, full cold, and A/C button on.
         2) Set blower/fan on high speed and open windows. Operate
system for 6-7 minutes to allow system to stabilize. Insert
thermometer in center vent, and measure temperature. Temperature at
center vent must be 19-40

ø

F (-7 to 4

ø

C) at center vent, with high side

and low side pressures within specification. See SPECIFICATIONS table
at beginning of article.

         AMBIENT TEMPERATURE SWITCH

         1) Remove air intake grille from right side cowl. Remove
switch from panel on right side of tray area. Place switch in freezer.
         2) Using a DVOM, check switch resistance. Switch resistance
must be infinite (no continuity) below 30

ø

F (-1

ø

C). Allow switch to

warm above 45

ø

F (7

ø

C). Switch resistance must be zero ohms

(continuity). Replace switch if necessary.

         COMPRESSOR CLUTCH COIL

         Disconnect compressor clutch harness connector. Check
resistance between clutch connector terminals. Resistance reading
should be 3.6 ohms. If resistance reading is not as specified, replace
clutch coil.

         DUAL-PRESSURE SWITCH

         High-Pressure Cut-Out Switch
         Locate dual-pressure switch on refrigerant line (right strut
tower). Switch is identified by its 4 wires. Ensure switch opens at
464 psi (32 kg/cm

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). Ensure switch closes at 348 psi (24 kg/cm

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).

NOTE:    Dual-pressure switch may be removed without discharging

A/C-HEATER SYSTEM - MANUAL 

         Low-Pressure Cut-Out Switch
         Locate A/C pressure switch on refrigerant line (right strut
tower). Switch is identified by its 4 wires. Ensure switch opens below
29 psi (2.0 kg/cm

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). Ensure switch closes above 43.5 psi (3.0 kg/cm

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).

Replace switch if necessary.

         REMOVAL & INSTALLATION

WARNING: To avoid injury from accidental air bag deployment, read and
         carefully follow all SERVICE PRECAUTIONS and DISABLING &
         ACTIVATING AIR BAG SYSTEM procedures.

         A/C-HEATER CONTROL PANEL

         Removal & Installation
         Remove control panel trim. Remove control panel mounting
screws and pull cover forward out of dashboard. Disconnect harness
connector and control cables. Remove A/C-heater control panel. To
install, reverse removal procedures.