OPERATIONAL TESTING
When trouble shooting and diagnosing an air conditioning system, always refer to the appropriate vacuum and wiring diagrams for the system involved. Refer to the applicable operational chart for characteristics, and note the following
- Blower operation at all 4-speeds and engagement of the compressor clutch would indicate that electrical circuits are functioning properly.
- If evaporator inlet pipe AND accumulator can surface both appear to be the same temperature when felt by hand, system is properly charged with refrigerant.
- Operation of mode selector lever to distribute air from designated outlets would indicate proper vacuum and diaphragm function.
INSUFFICIENT COOLING "QUICK-CHECK" PROCEDURE
This procedure may be used to determine whether or not the A/C system has the proper refrigerant charge, providing ambient air temperature is above 70°F. It can eliminate an entire system checkout.
- Engine must be warm, choke must be open, and throttle must be off fast idle speed cam. Open vehicle's doors and engine hood.
- Set function lever to "NORM" position, temperature lever at "COLD", and blower on "HI". Engine should be at normal slow idle speed.
- "Hand-feel" the temperature of the accumulator can surface AND the evaporator inlet pipe while the compressor is engaged. It is normal for the compressor to cycle on and off to meet system requirements.
- If can surface and evaporator inlet pipe are both at the same temperature, and slightly cooler than ambient air, system is normal.
- If inlet pipe is frosted or feels cooler than accumulator can surface, refrigerant charge is low.
- Add refrigerant in 1/4 lb. increments, allowing system to stabilize between additions, until both feel same temperature. Add 14 oz. more refrigerant.
INSUFFICIENT COOLING "THOROUGH CHECK" PROCEDURE
Note. CCOT system is not equipped with a sight glass, and under no conditions should a sight glass be installed.
- To thoroughly check refrigerant system, attach manifold gauge set, and refer to Insufficient Cooling Chart. Note that compressor clutch cycles on and off during normal operation.
- When using Insufficient Cooling Chart, note that minor variations occur in cycling pressures, but otherwise procedures apply to all models.
- In checking cycling of clutch on various models, it may be necessary to jumper different cut-off switches and relays to check system fully.
VACUUM SYSTEM DIAGNOSIS
- With engine idling, move mode selector lever to each position. Refer to appropriate vacuum diagram for proper airflow, air door functioning, and vacuum circuits.
- If airflow is not as shown in operational charts, check for poor vacuum hose connections at actuators, control head valve, reservoir, tees, etc.
- Check vacuum source circuit by installing tee and gauge (with restrictor) at vacuum outlet. Refer to appropriate vacuum diagram.
- Idle engine, and check that vacuum is equivalent to engine vacuum in all selector positions. If vacuum is less than normal in all positions, remove tee and connect gauge line directly to tank.
- If vacuum is still low, problem is in feed circuit. If vacuum is normal, problem is downstream. If vacuum is less than normal in some selected positions, leak is in these circuits.
- If vacuum was normal and even at all positions, malfunction is probably caused by improperly connected lines, plugged lines, or a defective vacuum valve(s).
- To check a specific vacuum circuit, place mode selector lever in the malfunctioning position. Check for vacuum at the affected actuator. If vacuum exists, but door does not move, actuator is defective or binding.
- If low or no vacuum exists at the actuator, determine whether vacuum harness or vacuum valve is faulty. Check vacuum harness first.
BLOWER MOTOR WON'T RUN
- Check for blown fuse.
- Turn ignition switch to "RUN" and check for voltage at function control switch.
- Switch blower selector to "HI" and check for voltage at switch and at high speed blower relay.
- Ground blower motor with ignition switch in "RUN".
BLOWER DOES NOT OPERATE IN "HI"
- Check for voltage at high speed blower relay with ignition switch in "RUN" and blower switch in "HI". If not OK, check for voltage at blower switch.
BLOWER OPERATES ONLY IN "HI"
- Check blower resistors for open condition.
BLOWER OPERATES IN "HI" WITH IGNITION SWITCH "OFF"
- Check the blower relay.
AIR CONDITIONER DOESN'T WORK
- With engine running and mode lever at "NORM", check for voltage at pressure cycling switch.
- Check for voltage between pressure cycling switch and compressor clutch.
- Ground compressor clutch circuit. If clutch engages, check wide-open throttle cut-out switch and A/C compressor cut-off switch.
