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2008 - MX-5 - HVAC

NO.6 AIR FROM VENTS NOT COLD ENOUGH



6

Air from vents not cold enough.

DESCRIPTION

  • Magnetic clutch operates but A/C system malfunctions.

POSSIBLE CAUSE

  • Drive belt malfunction

  • Malfunction in A/C unit or condenser

  • Malfunction in receiver/drier or expansion valve (valve closes too much)

  • Malfunction in refrigerant lines

  • A/C compressor system malfunction, insufficient compressor oil

  • Over filling of compressor oil, malfunction in expansion valve or A/C unit air intake link system


Diagnostic procedure

STEP

INSPECTION

ACTION

1

INSPECT DRIVE BELT

Yes

Go to the next step.

No

Adjust or replace drive belt, then go to Step 20.

2

INSPECT REFRIGERANT SYSTEM PERFORMANCE

Yes

Operation is normal. (Recheck malfunction symptoms.)

No

Go to the next step.

3

CHECK TO SEE WHETHER MALFUNCTION IS IN A/C UNIT INTAKE AND CONDENSER OR ELSEWHERE

  • Are refrigerant high-pressure and low-pressure values both high?

Yes

Go to the next step.

No

Go to Step 6.

4

INSPECT A/C UNIT INTAKE

  • Is A/C unit intake clogged?

Yes

Remove obstruction, then go to Step 20. (If air does not reach evaporator within A/C unit, heat exchange does not occur and refrigerant pressure becomes high.

Therefore, removal of obstruction is necessary.)

No

Go to the next step.

5

INSPECT CONDENSER

Yes

Adjust refrigerant to specified amount, then go to Step 20. (Excessive amount of refrigerant.)

No

Replace condenser, or repair and clean condenser fins, then go to Step 20. (See CONDENSER REMOVAL/INSTALLATION.)

6

CHECK TO SEE WHETHER MALFUNCTION IS IN EXPANSION VALVE, RECEIVER/DRIER AND REFRIGERANT LINES OR ELSEWHERE

  • Are refrigerant high-pressure and low-pressure values low?

Yes

Go to the next step.

No

Go to Step 14.

7

CHECK TO SEE WHETHER 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 the next step.

No

Go to Step 10.

8

CHECK TO SEE WHETHER MALFUNCTION IS IN EXPANSION VALVE OR RECEIVER/DRIER

  • Turn A/C switch off and let air conditioner stop for 10 min.

  • Start engine.

  • Turn both A/C switch and fan switch on.

  • Does malfunction occur after A/C compressor turns on?

Yes

Go to the next step.

No

Replace condenser and apply vacuum to refrigerant line for more than 30 min using vacuum pump, add refrigerant to specified level, then go to Step 20. (Since water has intermixed in receiver/drier and it is saturated, replacement is necessary.) (See CONDENSER REMOVAL/INSTALLATION.)

9

VERIFY THAT EXPANSION VALVE HEAT-SENSING TUBE WITHIN A/C UNIT IS POSITIONED SECURELY AND CORRECTLY

  • Is expansion valve heat-sensing tube within A/C unit securely installed in proper position?

Yes

Replace expansion valve, then go to Step 20. (Since valve closes too much, replacement is necessary.) (See A/C UNIT DISASSEMBLY/ASSEMBLY.)

No

Install heat-sensing tube securely in proper position, then go to Step 20.

10

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?

    • Are piping installation points on condenser free of gas leakage?

    • Are piping installation points on receiver/drier free of gas leakage?

    • Are piping installation points on A/C compressor free of gas leakage?

    • Are piping installation points on A/C unit free of gas leakage?

    • Perform gas leak inspection using gas leak tester.

  • Are above items okay?

Yes

Go to the next step.

No

If piping or A/C component(s) are damaged or cracked, replace them.

Then go to Step 20.

If there is no damage, go to Step 13.

11

INSPECT EVAPORATOR PIPING CONNECTIONS IN A/C UNIT FOR GAS LEAKAGE

  • Are piping connections for evaporator in A/C unit free of gas leakage?

Yes

If the vane makes a noise, add 10 ml {10 cc, 0.34 fl oz} of compressor oil to the A/C compressor. Verify that the noise is no longer heard.

Adjust refrigerant to specified amount, then go to Step 20.

No

If piping is damaged or cracked, replace it.

Then go to Step 20.

If there is no damage, go to the next step.

12

INSPECT EVAPORATOR PIPING CONNECTIONS IN A/C UNIT FOR LOOSE

  • Are piping connections for evaporator in A/C unit loose?

Yes

Tighten connections with specified torque, adjust both compressor oil and refrigerant to specified amount, then go to Step 20.

No

If the vane makes a noise, add 10 ml {10 cc, 0.34 fl oz} of compressor oil to the A/C compressor. Verify that the noise is no longer heard.

Replace O-ring on piping, adjust refrigerant to specified amount, then go to Step 20.

13

INSPECT PIPING CONNECTIONS FOR LOOSE

  • Are piping connections loose?

Yes

Tighten connections with specified torque, adjust both compressor oil and refrigerant to specified amount, then go to Step 20.

No

If the vane makes a noise, add 10 ml {10 cc, 0.34 fl oz} of compressor oil to the A/C compressor. Verify that the noise is no longer heard.

Replace O-ring on piping, adjust refrigerant to specified amount, then go to Step 20.

14

CHECK TO SEE WHETHER MALFUNCTION IS IN EXPANSION VALVE, AIR MIX ACTUATOR AND COMPRESSOR OIL OR ELSEWHERE

  • Does refrigerant high-pressure value hardly increase?

Yes

Go to the next step. (Pressure hardly increases.)

No

Go to Step 17.

15

CHECK TO SEE WHETHER 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 3.

No

Go to the next step.

16

CHECK TO SEE WHETHER MALFUNCTION IS IN COMPRESSOR OIL AMOUNT OR A/C COMPRESSOR

  • After compressor oil is replenished each 10 ml {10 cc, 0.34 fl oz}, does high-pressure value increase?

Yes

Troubleshooting completed. (Explain to customer that cause was insufficient compressor oil.)

No

Replace A/C compressor, then go to Step 20. (Cause is defective A/C compressor.) (See A/C COMPRESSOR REMOVAL/INSTALLATION.)

17

CHECK TO SEE WHETHER MALFUNCTION IS IN EXPANSION VALVE OR ELSEWHERE

  • Is only refrigerant low-pressure value high?

Yes

Go to Step 19.

No

Go to the next step.

18

VERIFY THAT AIR MIX IS INSTALLED SECURELY AND PROPERLY

  • Are A/C unit air mix links, air mix cranks, and air mix rods securely and properly installed?

Yes

Set fan switch to 4th position.

Turn A/C switch on.

Set FRESH mode.

Set temperature control to MAX COLD.

Set VENT mode.

  • (1)Start and run the engine at 1,500 rpm for 10 min.

  • (2)Run the engine at idle for 1 min.

  • (3)Within 12 s, idle → 4,000 rpm → idle. Perform cycle 5 times.

  • (4) Run the engine at idle for 30 s.

  • (5)Drain the compressor oil completely from the A/C compressor and verify the amount.

    • If there is approx. 90 ml {90 cc, 3.0 fl oz} of compressor oil, go to Step 20.

    • If there is more than 90 ml {90 cc, 3.0 fl oz} of compressor oil, remove surplus oil and fill A/C compressor with 90 ml {90 cc, 3.0 fl oz} of compressor oil. Repeat Steps (1) to (5).

(Cause is excessive amount of compressor oil.)

No

Repair or install links, cranks and rods securely in proper position, then go to Step 20.

19

VERIFY THAT EXPANSION VALVE HEAT-SENSING TUBE WITHIN A/C UNIT IS POSITIONED SECURELY AND CORRECTLY

  • Is expansion valve heat-sensing tube within A/C unit securely installed in proper position?

Yes

Replace expansion valve, then go to the next step. (Since valve opens too much, replacement is necessary.)

No

Install heat-sensing tube securely in proper position, then go to the next step.

20

VERIFY THAT MALFUNCTION SYMPTOM OCCURS AFTER REPAIR

  • Does cool air blow out? (Are results of refrigerant system performance test okay?)

Yes

Troubleshooting completed.

Explain repairs to customer.

No

Recheck malfunction symptoms, then repeat from Step 1 if malfunction recurs.




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