Tuesday, September 23, 2008

Honda Civic a/c will not work

Honda Civic a/c will not work

VEHICLE: 2002 Honda Civic LX 1.7L, L4, MFI, SOHC, VIN -, Eng Desg D17A1, Eng Version N/R, 1700 CC


MILEAGE: 113000

Customer Concern: The A/C compressor will not operate. Also, the scan tool does not indicate that there is any A/C request.

Tests:



1. Locate the A/C pressure switch on the high side A/C line by the alternator. The wire colors are Red (RED) and Blue (BLU). With the pressure switch unplugged, the RED wire should have 10 to 12 volts reference voltage on a voltmeter. When the reference voltage is grounded, the Multiplex Control Unit (MCU) will see an A/C request and send that request to the Engine Control Module (ECM).


2. If there is no voltage to the A/C pressure switch, unplug the A/C Compressor 3-terminal connector, check the Blue/White (BLU/WHT) wire on the harness side of the connector, and look for voltage. If there is voltage, then backprobe the BLU/WHT wire, plug in the connector and start the vehicle. Then ground the BLU/WHT wire and verify that the A/C compressor and condenser fan operate.


3. Test the A/C Thermal Protector. The voltage on the BLU/WHT wire should go through the A/C Thermal Protector and then to the A/C Pressure switch RED wire. Check to see if the A/C Thermal Protector is open or if there is a wire harness problem between the A/C Thermal Protector and the pressure switch.


4. Always verify that there are no codes in the climate control system. If there is a problem, the climate control may not ground the A/C request circuit.


Potential Causes:

Harness

Heater Ventilation Air Conditioner (HVAC) Thermal Protector

Confirmed Fix:

Replaced Auxiliary Heater Ventilation Air Conditioner (HVAC) Control Module

Replaced Heater Ventilation Air Conditioner (HVAC) Thermal Protector

Tech Tips: The heater control panel was not grounding the Blue wire.

Never jump voltage to the A/C request circuit when testing out the A/C system.


Spark plug wires
Exhaust and convertors
K&n oil and air filters
Oxygen or o2 sensor
Brakes
Step by step instructions on how to change your own spark plugs and wires
Keep your engine properly tuned

4 comments:

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  2. Your articles have really been helpful in troubleshooting and locating some parts that I can't find directly in my car. Your approach is direct and really straight to what I am looking for.

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  4. Im glad I can be of help. If you have any questions please feel free to post them. Ill do my best to help you out. Consider me your online helper. And it is always cheaper to do some simple routine maintenance yourself. Changing your oil, replacing brake pads, things of that nature can save you hundreds of dollars in the long run. Good techs/mechanics are expensive. And they should be. An ASE certified tech spends alot of time in the classroom learning the new applications on each and every new vehicle on the market today. People complain that mechanics are a rip off and way too expensive. But if those same people only realized how much class time and dedication it takes to become a quality tech, they would understand a little more.

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