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1. Perform diagnostic system check. See DIAGNOSTIC SYSTEM CHECK under
TROUBLE SHOOTING. After diagnostic system check, go to next step.
2. Start engine and allow to idle in park. Use scan tool to display HVAC data list. Switch
HVAC control through the following operating modes. See SOLENOID SCAN TOOL
DISPLAY table. If scan tool indicates correct combination of vacuum/electric solenoids on
and off in all operating modes listed, go to next step. If scan tool does not indicate correct
combination of vacuum solenoids on and off in all operating modes listed, replace HVAC
control head and go to step 7 . See HVAC CONTROL HEAD under REMOVAL &
INSTALLATION.
SOLENOID SCAN TOOL DISPLAY
Operating Mode
Upper
Bi-Level
Lower
Defog
Defrost
Fresh Air
Recirculated Air
3. Disconnect vacuum line connector to vacuum/electric solenoid. Connect a vacuum gauge to
Purple vacuum line. Start engine and allow to idle in park. If vacuum reading is within 10-
17 in. Hg, go to next step. If vacuum reading is not within 10-17 in. Hg, repair leak or
restriction in Purple vacuum supply line, vacuum tank or manifold vacuum line to vacuum
tank and go to step 7 .
4. Disconnect vacuum lines at vacuum/electric solenoid (located under right side of dashboard,
on blower motor housing). Using a hand-held vacuum pump, apply vacuum to each vacuum
actuator supply lines at vacuum/electric solenoid connector. Apply vacuum to each vacuum
actuator. Listen for door movement within HVAC module assembly. If necessary, turn
ignition on and blower motor to high speed position to verify door operation. If vacuum
actuators hold vacuum and effectively control door operation, go to next step. If vacuum
actuators do not hold vacuum and effectively control door operation, inspect and repair or
replace any sticking or binding doors, inoperative vacuum actuators or vacuum supply lines.
After repairs, go to step 7 .
5. Disconnect vacuum/electric solenoid electrical connector. Measure voltage between ground
and terminal No. 6 (Brown wire) of vacuum/electric solenoid. Turn ignition on. If battery
voltage exists, go to next step. If battery voltage does not exist, repair open or high
2001 Chevrolet Corvette
2000-01 AUTOMATIC A/C-HEATER SYSTEMS Corvette
Solenoids (No.) On
Heater (2) & Mode Open (5)
Heater (2) & Mode Closed (3)
Mode Closed (3)
Defrost (1) & Mode Closed
Heater (2)
(3)
.....
Air Inlet (4)
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