Diagnostic Procedure

WARNING: This page is about a different car, the 2005 Mazda MX-5 Miata. However, it is still accessible from the selected car via links, so may be relevant.

AIR FROM VENTS NOT COLD ENOUGH - DIAGNOSTIC PROCEDURE

STEP	INSPECTION		ACTION
1	CHECK TO SEE WHETHER VENT AIR TEMPERATURE IS NORMAL OR NOT Is vent air temperature 6 °C {43 °F} or less ?	Yes	Operation is normal. (To prevent evaporator within cooling unit from freezing, A/C compressor stops right away when vent air temperature is 6 °C {43 °F} or less.
1		No	Go to next step.
2	INSPECT REFRIGERANT SYSTEM PERFORMANCE Carry out refrigerant system performance test. (See REFRIGERANT SYSTEM PERFORMANCE TEST .) Is operation normal?	Yes	Operation is normal. (Reinspect malfunction symptoms.)
2		No	Go to next step.
3	INSPECT DRIVE BELT Inspect drive belt. (See DRIVE BELT INSPECTION .) Is it okay?	Yes	Go to next step.
3		No	Adjust or replace drive belt, then go to Step 20. (See DRIVE BELT ADJUSTMENT .)
4	CHECK TO SEE MALFUNCTION IS IN BLOWER UNIT INTAKE AND CONDENSER OR ANOTHER Inspect refrigerant pressure. (See REFRIGERANT PRESSURE CHECK .) Are both high-pressure and low-pressure values high?	Yes	Go to next step.
4		No	Go to Step 7.
5	INSPECT BLOWER UNIT INTAKE Is blower unit intake clogged?	Yes	Remove obstruction, then go to Step 20.(If air does not reach evaporator within cooling unit, heat exchange does not occur and refrigerant pressure becomes high. Therefore, removal of obstruction is necessary.)
5	INSPECT BLOWER UNIT INTAKE Is blower unit intake clogged?	No	Go to next step.
6	INSPECT CONDENSER Inspect condenser. (See CONDENSER INSPECTION .) Is it okay?	Yes	Adjust refrigerant to specified amount, then go to Step 20.(Excessive amount of refrigerant.)
6		No	Replace condenser, or repair and clean condenser fins, then go to Step 20.
7	CHECK TO SEE IF MALFUNCTION IS IN EXPANSION VALVE, RECEIVER/DRIER AND REFRIGERANT LINES OR ELSEWHERE Are refrigerant high-pressure and low-pressure values low?	Yes	Go to next step.
7		No	Go to Step 13.
8	CHECK TO SEE IF MALFUNCTION IS IN EXPANSION VALVE AND RECEIVER/DRIER OR ELSEWHERE Immediately after A/C compressor operates, does refrigerant high-pressure value momentarily rise to correct value, then fall and stay below it? (Is there negative pressure on low-pressure side?)	Yes	Go to next step.
8		No	Go to Step 11.
9	CHECK TO SEE IF MALFUNCTION IS IN EXPANSION VALVE OR RECEIVER/DRIER Turn A/C switch off and let air conditioner stop for 10 minutes. Start engine. Turn both A/C switch and fan switch on. Does malfunction occur after A/C compressor turns on?	Yes	Go to next step.
9		No	Replace receiver/drier, then go to Step 20.(Since water has intermixed in receiver/drier, replacement is necessary.)
10	VERIFY THAT EXPANSION VALVE HEAT-SENSING TUBE WITHIN COOLING UNIT IS POSITIONED SECURELY AND CORRECTLY Is expansion valve heat-sensing tube within cooling unit securely installed proper position?	Yes	Replace expansion valve, then go to Step 20.(Since valve closes too much, replacement is necessary.)
10		No	Install heat-sensing tube securely in proper position, then go to Step 20.
11	INSPECT REFRIGERANT LINES Inspect refrigerant lines. Is piping free of damage and cracks? Are piping connections free of oil grime? (Visual inspection) Are piping connections free of gas leakage? (Inspect using gas leak tester.) Are above items okay?	Yes	If the vane makes a noise, add 10 ml {10 cc, 0.338 fl oz} of compressor oil to the A/C compressor. Verify that the noise is no longer heard. Adjust refrigerant to specified amounts, then go to Step 20.
11		No	If piping is damaged or cracked, replace it, then go to Step 20.If there is no damage, go to next step.
12	INSPECT PIPING CONNECTIONS FOR LOOSENESS Are piping connections loose?	Yes	Tighten connections to specified torque. If the vane makes a noise, add 10 ml {10 cc, 0.338 fl oz} of compressor oil to the A/C compressor. Verify that the noise is no longer heard. Adjust refrigerant to specified amounts, then go to Step 20. If the vane makes a noise, add 10 ml {10 cc, 0.338 fl oz} of compressor oil to A/C compressor. Verify that the noise is no longer heard.
12		No	Replace O-ring on piping, adjust refrigerant to specified amounts, then go to Step 20.
13	CHECK TO SEE IF MALFUNCTION IS IN EXPANSION VALVE, AIR MIX ACTUATOR AND COMPRESSOR OIL OR ELSEWHERE Does refrigerant high-pressure value hardly increase?	Yes	Go to next step. (Pressure hardly increases.)
13		No	Go to Step 16.
14	CHECK TO SEE IF MALFUNCTION IS IN COMPRESSOR OIL AMOUNT AND A/C COMPRESSOR OR ELSEWHERE When engine is racing, does high-pressure value increase?	Yes	Return to Step 4.
14		No	Go to next step.
15	CHECK TO SEE IF MALFUNCTION IS IN COMPRESSOR OIL AMOUNT OR A/C COMPRESSOR After compressor oil is replenished each 10ml {10 cc, 0.338 fl oz}, does high-pressure value increase?	Yes	Troubleshooting completed. (Explain to customer that cause was insufficient compressor oil.)
15		No	Replace A/C compressor, then go to Step 20.(Cause is defective A/C compressor.)
16	CHECK TO SEE IF MALFUNCTION IS IN EXPANSION VALVE OR ELSEWHERE Is only refrigerant low-pressure value high?	Yes	Go to Step 19.
16		No	Go to next step.
17	VERIFY THAT AIR MIX ACTUATOR IS INSTALLED SECURELY AND PROPERLY Are heater unit air mix links, air mix cranks and air mix rods securely and properly installed?	Yes	Go to next step.
17		No	Repair or install links, cranks and rods securely in proper position, then go to Step 20.
18	ADJUST COMPRESSOR OIL Set the fan switch to the 4th position. Turn the A/C switch on. Set to FRESH mode. Set the temperature control to MAX COLD. Set to VENT mode. Run engine at a constant 1,500 RPM for 10 minutes. Run engine at idle speed for 1 minute. 1 engine speed cycle is defined as going from idle speed to 4,000 RPM and back to idle speed over a period of 12 seconds. Perform 5 cycles. Run engine at idle speed for 30 seconds. Remove all compressor oil from A/C compressor and verify that it is 90 ml {90 cc, 3.0 fl oz}. If it is more than 90 ml {90 cc, 3.0 fl oz}, put only 90 ml {90 cc, 3.0 fl oz} back into A/C compressor. Carry out above steps 1 to 10 again and verify that compressor oil is 90 ml {90 cc, 3.0 fl oz}. Is there 90 ml {90 cc, 3.0 fl oz} of compressor oil in A/C compressor?	Yes	Go to Step 20.
18		No	Readjust until compressor oil is 90 ml {100 cc, 3.0 fl oz}.
19	VERIFY THAT EXPANSION VALVE HEAT-SENSING TUBE WITHIN COOLING UNIT IS POSITIONED SECURELY AND CORRECTLY Is expansion valve heat-sensing tube within cooling unit securely installed in proper position?	Yes	Replace expansion valve, then go to next step. (Since valve opens too much, replacement is necessary.)
19		No	Install heat-sensing tube securely in proper position, then go to next step.
20	VERIFY THAT MALFUNCTION SYMPTOM DOES NOT OCCUR AFTER REPAIR Is cool air discharged? (Are results of refrigerant system performance test okay?)	Yes	Troubleshooting completed. Explain repairs to customer.
20		No	Recheck malfunction symptoms, then repeat from Step 1 if malfunction recurs.