Complete System Checks
Whenever further, more specific tests are indicated by preliminary checks to pinpoint component failures, use the SYSTEM CHECKS chart and its accompanying VACUUM SYSTEM COMPONENT FUNCTION chart to perform these tests. The COMFORTRON WIRING DIAGRAM and the COMFORTRON VACUUM DIAGRAM can be used to trace the failure by linking the connector numbers. Warm up engine before starting tests.
SYSTEM CHECKS
| Step | Tester Settings | Tester Should Indicate: | To Correct Abnormal Indication: | ||
|---|---|---|---|---|---|
| Rocker Switch | Voltage | Manual Control | |||
| 1 | Manual | Source | 150 | Battery Voltage | Check fuse and wiring. |
| 2 | Manual | 1 Sensor | 150 | Battery Voltage | Check for open in sensor circuit. |
| 3 | Manual | Amplifier or Control Cal. | a. Max. Heat* | 0-4 Volts | See Service Manual: Malfunctioning Amplifier or Temperature Dial. |
| b. Max. Cold* | 8 Volts Min. | ||||
| 4 | Manual | Transducer | a. Max. Cold* | 8 Volts Min. 0-3 in. Vac. | Check for open or bad ground in transducer circuit. Check vacuum relay valve when voltage is correct but vacuum is incorrect in max. cold position. |
| b. Max. Heat* | 0-4 Volts 9 in. Min. Vac. | ||||
| 5A | Manual | Amplifier or Control Cal. | Set to 150 for Comfortron System | 6.5 Volts | Rotate car temperature dial until meter reads 6.5 volts. Car temperature should indicate 3. If not, see TEMPERATURE calibration which follows. |
| 5B | Automatic | Amplifier or Control Cal. | Same as 5A. Allow 5 min. for system to stabilize with doors and windows closed. | 5.5 to 7.5 Volts | After 5 minutes of operation check for defective sensor. |
| Control Head Setting | Tester Settings | Tester Should Indicate: | If not, check the following: | Electrical Diagram Probe Points: | Voltmeter should read | ||
|---|---|---|---|---|---|---|---|
| Function | Manual Control | Voltage | |||||
| Med | Manual | Max. Heat | Transducer | High Blower Maximum Heat | Fuse in Block | 1-2 | Battery Voltage |
| In Line Fuse | 8-9 | Battery Voltage | |||||
| High Blower Relay | 10-21 | Battery Voltage | |||||
| 20 | Minimum 6 volts | ||||||
| Master Thermistor | 18 | Battery Voltage | |||||
| 19 | Minimum 6 volts | ||||||
| Power Servo | 39-46 | Battery Voltage | |||||
| Blower Switch | 3 | Battery Voltage | |||||
| Resistor | 22-15 | Battery Voltage | |||||
| Blower Motor | 16 | Battery Voltage | |||||
| Wiring Harness | Checked during above procedure. (This is a complete step-by-step high blower circuit check which also checks wiring harness.) | ||||||
| Blower Switch | 4 | Minimum 6 volts | |||||
| Lo | Manual | Max. Heat | Transducer | Reduced Blower Speed | Master Relay | 12-13 | Battery Voltage |
| 7 | Minimum 6 volts | ||||||
| Resistor | 14 22-15 |
Battery Voltage Minimum 5 volts | |||||
| Power Servo | 39-46 | Minimum 5 volts | |||||
| Blower Motor | 16 | Minimum 5 volts | |||||
| RESISTOR CHECK | |||||||
| Lo | Manual | Rotate from Max. Heat to Max. Cold | Transducer | Complete series of blower changes from Hi to Lo to Hi again. | Resistor Disconnect Power Servo Connector | 14 | Battery Voltage |
| 22-40-42-44-15 | Voltage should vary between 7 & 3 volts (approx.) | ||||||
| AMPLIFIER CHECK | |||||||
| Med | Manual | 150 | Amplifier | Remove conn. from control head temperature dial. Voltage reading should be 9 volts minimum. Short this lead to ground. Voltage reading should be 0 volts. No voltage change indicates malfunctioning of amplifier. |
|||
| COMPRESSOR CLUTCH CHECK | |||||||
| Med | Manual | Max. Cold | Transducer | Cooling System Operation | Compressor Clutch (Grille Temp, must be above 40°.) | 26-27-28 | Battery Voltage |
| DE-ICE CIRCUIT | |||||||
| De-Ice 1 on Temp. Dial | Automatic | Max. Cold | Probe | Assuming rest of system is operating normally: Max. Heat to windshield. |
Blower Switch | 4 | Battery Voltage |
| Master Relay | 20-10-21 | Battery Voltage | |||||
| Transducer | 38 | Zero Voltage | |||||
| SENSOR STRING CHECK | |||||||
| Med | Automatic | Probe | - | Sensor String | 29-30 | Battery Voltage | |
| POWER SERVO FEEDBACK POTENTIOMETER CHECK | |||||||
| Med | Manual | Rotate slowly from max, cold to max. heat and vice-versa | Transducer | Remove Power Servo 6-terminal connector and install ohmmeter at pink and yellow connections (points 32 and 33). Ohmmeter needle should move smoothly from approximately 70 ohms at max. cold to approximately 15 ohms at max. heat, or vice-versa. If an erratic movement is noted, the feedback potentiometer is defective. | |||
| TRANSDUCER CHECK | |||||||
| Med | Manual | Max. Cold | Transducer | 0-3" Vac. Reading 8 Volts Min. | Transducer voltage (at Max. Cold position) | 38-48 | 8 volts minimum |
|
NOTE:
If voltage is correct but vacuum is incorrect, check vacuum relay valve as noted below.
|
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| Max. Heat | 9" Min. Vac. Reading 0-4 Voltage Reading | Transducer Ground | |||||
VACUUM SYSTEM COMPONENT FUNCTION VACUUM RELAY VALVE CHECK
| Control Head Setting | Tester Settings | Tester Should Indicate: | If not, check the following: | Electrical Diagram Probe Points: | Voltmeter should read | ||
|---|---|---|---|---|---|---|---|
| Function | Manual Control | Voltage | |||||
| Med | Manual | Max. Cold | Transducer | With tester box vacuum gauge connected to large port on vacuum relay and the small port (maroon) on the same side sealed, vacuum gauge should indicate no vacuum. If vacuum is indicated, vacuum relay valve is defective. | |||
| VACUUM FUNCTION CHECKS | |||||||
| Med | Manual | Max. Heat | Trans. | Hi Blower Outside air (air door closed to car body). Hot air from heater outlets. | Defective Power Servo; Leak in Vacuum System; Temp.; Door Link Disconnected or Jammed; Defective Vacuum Relay Valve | ||
| Max. Cold | Hi Blower Recirc. Air (air door open to car body) cold air from A/C outlets. | Defective Mode Door Diaphragm | |||||