Visual Check
If car is being serviced for high outlet temperatures on the road, but appears to operate normally in shop, make the following quick check to determine which unit is at fault.
- Check temperature door to make sure it seals in the cool position. If not sealing, refer to TEMPMATIC BLOWER DIAGNOSIS CHART in this article.
- Check aspirator hose and hose to grille and ducts for proper connections. Check vacuum hoses for correct routing and connection. See Fig 1illustrations .
- Check sealing between evaporator housing and cowl. Check suction line (should be cold or frosty). Check sight glass for "clear" condition. Check compressor clutch to make sure that it engages. Check compressor belt for proper adjustment.
NOTE:
For other diagnosis procedures, see appropriate DIAGNOSIS CHART in this article.
DIAGNOSIS - PERFORMANCE TEST RESULTS
| CONDITION AND CAUSE | CORRECTION |
|---|---|
| EVAPORATOR PRESSURE TOO HIGH | |
| A. Loose compressor drive belt. | A. Adjust as outlined |
| B. Defective clutch or coil. | B. Check or replace as necessary |
| C. Restriction in suction line. | C. Remove, inspect and clean or replace. |
| D. Possible defective suction throttling valve. | D. Refer to diagnosis chart in Section 1A. |
| E. Possible defective expansion valve. | E. Refer to diagnosis chart in Section 1A. |
| HIGH PRESSURE SIDE OF SYSTEM TOO HIGH | |
| A. Engine overheated. | A. Check engine cooling system. |
| B. Restricted air flow through condenser. | B. Remove foreign material from engine radiator and condenser. |
| C. Air in system or overcharge of refrigerant. | C. Momentarily discharge system on discharge side with engine not running; then, operate system and recheck pressure. Repeat as necessary. Check sight glass with system under load. |
| D. Too much oil in compressor. | D. Drain oil and add correct amount. |
| E. Restriction in condenser or any discharge or liquid line. | E. Remove parts, inspect for restricted passage, and clean or replace. |
| NOZZLE DISCHARGE: AIR TOO WARM (With Other Readings OK) | |
| A. Low refrigerant charge. | A. Check and add as necessary. |
| B. Air hoses not properly connected. | B. Inspect air hoses and manifolds. |
| C. Temperature Control Cable misadjusted. | C. Adjust. |
| D. Poor Seal-Evaporator to cowl. | D. Correct sealing. |
| CLUTCH SLIPPAGE | |
| A. Head pressure too high. | A. Discharge system until bubbles appear in sight glass and then add 1 1/2 pounds of refrigerant. |
| B. Pulley wobbles. | B. Check and replace, if necessary, the pulley bearing. If pulley has been work by bearing, replace pulley. |
| VELOCITY OF AIR AT DISCHARGE NOZZLES TOO LOW | |
| A. Restricted air hoses. | A. Inspect and replace if necessary. |
| B. Defective blower motor. | B. Check and replace if necessary. |
| C. Defective switches | C. Check and replace if necessary. |
| D. Poor wiring connection (Low voltage at blower). | D. Correct wiring. |
| E. Restricted evaporator core in evaporator assembly. | E. Wash evaporator core. Restricted evaporator core caused by freezing. |
| EVAPORATOR PRESSURE TOO LOW | |
| A. Insufficient Refrigerant charge. | A. Add refrigerant. |
| B. Restricted air flow through evaporator. | B. Check air flow. |
| C. Possible defective suction throttling valve. | C. Refer to diagnosis chart in Section 1A. |
| D. Possible defective expansion valve. | D. Refer to diagnosis chart in Section 1A. |
| INOPERATIVE CONTROLS | |
| A. Inadequate vacuum. | A. Check vacuum. All controls should move with 10" of vacuum. Check for pinched or leaking hoses. |
| B. Temperature cable improperly adjusted. | B. Adjust cable. |