AfterMarketNews Auto Care Pro AutoProJobs Auto-Video.com Brake&Frontend BodyShopBusiness Counterman EngineBuilder Fleet Equipment ImportCar Motorcycle & Powersports News Servicio Automotriz Shop Owner Tire Review Tech Shop Tomorrow's Tech Underhood Service

No More Free Tire ­Rotations!

Tire rotation is a cornerstone of vehicle preventive maintenance and tire longevity. It is a well-proven fact that tire tread life can be greatly enhanced by regular and timely tire rotation. During rotation, each tire and wheel is ­removed from...

Read more...

ASE G1: How To Measure Cold Cranking Amps, Reserve Capacity

The ASE G1 test contains 55 scored, job-related questions, 15% of which will concern electrical maintenance and repairs. From the ASE G1 study guide, you will need to know how to: • Perform battery tests (load and capacitance); ­determine needed...

Read more...

ASE A5: Brake Fluid And Bleeding Sequence

The ASE A5 Test includes a portion on brake fluid, bleeding, flushing and leak testing. You must know how to: • Diagnose poor stopping, pulling, dragging, or incorrect pedal travel caused by problems in the brake fluid; determine needed repairs. •...

Read more...

When Timing Is Everything: A Look At The 2.5L, 2.0L Powerplants

Last month, we looked at the timing chain setup on the Audi 3.2L engine and saw how a lack of oil changes can adversely affect the tensioners and cause engine failure. We’ve also seen similar issues with the timing chain setups on the 2.5L 5-cylinder...

Read more...

Modern Charging Systems: Cover All The Bases During the Diagnostic Process

To quote a familiar situation: “My customer’s car is now on its third alternator in six months and my jobber store refuses to ­warranty a fourth.” In other words, the parts supplier believes that an underlying problem is causing these alternators...

Read more...

Audi Fuel System: MIL On/Multiple Low Fuel Pressure DTCs

Due to fuel intrusion into the low-pressure ­system fuel pressure sensor (G410), a false signal may be sent to the controller, resulting in a reading that is out of tolerance. Model: 2007 Audi A4 Sedan V6-3.2L Scenario: The MIL is on and one or...

Read more...

Your Guide to the Kia Brake Job

Kias will provide little challenge for any tech currently handling basic brake work. All it takes is paying attention to details and good work habits to make it profitable. An occasional long pedal could be a master cylinder bleeding down, which...

Read more...

Toyota Avalon Alignment Spec: 2005-‘11

The Toyota Avalon is sometimes called the “Japanese Buick” due to its size and plush ride. However, the Avalon’s overall suspension design does not vary that much from Toyota’s smaller vehicle platforms. The Avalon comes in four trims:...

Read more...

BYOBP Brake Jobs: This Has To Stop

Recently, I was sent a link to a TV commercial on YouTube for a mobile brake business. I will post the link on BrakeandFrontEnd.com. The commercial featured a puppet claiming that the business could save a driver $500 on brakes because shops mark up brake...

Read more...

Redline Detection Seeks Nominations for 2nd Annual Redline Rock Star Performance Award

Redline Detection is encouraging anyone who works with, or knows, a talented technician to nominate him or her for the second annual Redline Rock Star Performance Award. The award recognizes a technician for their commitment to family, community and...

Read more...

Automotive Lift Institute (ALI) Elects 2015 Board

Jerome Lentz of Challenger Lifts (Louisville, Ky.) has been elected chairman of the Automotive Lift Institute (ALI) Board of Directors for 2015. Voting took place at ALI’s annual membership meeting Nov. 3 in Las Vegas. Lentz’s 2015 term will be...

Read more...

Top 5 Tools: John Forro, AST, Automotive Service Technology in Hinckley, OH

John Forro AST, Automotive Service Technology Hinckley, OH ALLDATA Information System: I use this system daily for researching labor pricing, wiring schematics, circuit descriptions, torque specs, etc. One doesn’t need to memorize all the information...

Read more...

Home Climate Control Tech Tip: Volkswagen Has No Power to the A/C Compressor Clutch

Print Print Email Email

Vehicle Application: 2000 Beetle 2.0, 2002 Beetle 1.9, 2002 Golf 1.8, 1999-2003 Golf 2.0, 2000-’05 Jetta 1.8, 1.0, 1999-2005 Jetta 2.0 and 2000-’02 Jetta 2.8

Customer Concern: The A/C is not working. There is no power to the A/C compressor clutch and it does not engage. (Manual climate control.)

Potential Causes: A/C Compressor, A/C Pressure Sensor F129, A/C Switch, Ambient Temperature Switch F38, Battery Auxiliary Fuse Box, Fan Control Module J293 (and Wiring), Fuse or Lost Throttle Basic Settings

Tests/Procedures:

Test the Fan Control (FCM) module inputs as follows:

1. All tests are performed with the ignition key and A/C switched on and the connectors connected to the fan module. The fan control module is located under the radiator and has two connectors: a 14-pin (T14) and a 4-pin (T4).

2. Check for 12 volts to pin T4a/1 (red/black) and T4a/3 (red) via fuses S164 and S180 respectively, in the fuse box on top of the battery, at all times. (Note: It’s critical to check these power sources in a loaded condition as damage to the battery auxiliary fuse box can cause a loss of voltage under load. Visually inspect the condition of the three push-in type fuses for corrosion and burn marks.)

3. Verify an approximate 70% duty cycle from the A/C pressure sensor at pin T14/2 (white) with the ignition on and the compressor not running (duty cycle will decrease as the high-side pressure increases). A duty cycle above 80 or below 10 will command the compressor off and would indicate a faulty pressure sensor, if the compressor is not running and the refrigerant levels are normal.

4. Verify 12 volts to pin T14/4 (red/gray) via fuse 16, at all times.

5. Verify good ground to pin T14/6 (brown/black).

6. When the A/C is switched on and the blower motor is running at any speed, verify that 12 volts from the A/C switch in the instrument panel is available to pin T14/8 (blue/red). Note: The cooling fans should run at low speed whenever the A/C is switched on.

7. Verify 12 volts to pin T14/9 (black/blue) from fuse #5, when the ignition is in the “on” position.

8. Verify the presence of an 11-volt reference (actual voltage reading will oscillate between 7, 9 and 11 volts) at pin T14/13 (purple/yellow). The instrument cluster will ground this reference to request a compressor shutdown for an overheat condition. The cooling fans will also be running on high speed.

9. Disconnect the 14-pin connector. Using a fused 12-volt jumper, apply power to pin T14/10 (green/black). The compressor clutch should engage. If the compressor does not engage, check for a wiring harness open circuit or loss of ground at the compressor. Reconnect the 14-pin connector.

10. Disconnect the 14-pin connector and verify continuity between pin T14/14 (green/blue) and T14/5 (blue/red). This checks the Ambient Temperature Switch (ATS) (normal open circuit below 32° F, continuity above 32° F).

11. Verify the presence of an 11-volt reference voltage at pin T14/3 (green). The engine control module (ECM) will ground this reference to request a compressor shutdown for a wide open throttle (WOT) condition or lack of throttle basic setting. Eleven volts is the normal expected reading at this pin.

12. If all tests pass, the FCM is faulty and must be replaced.

Tech Tips:

Note: Pin T14/3 will be grounded by the ECM if the throttle basic settings are lost. Raising the engine rpm over 2,500 will cause the ECM to allow A/C operation if this is the case. If a ground condition exists on pin 3, perform a throttle basic setting procedure and recheck for correct voltage.

If needed, a repair kit is available from Volkswagen to replace the 14-pin fan control module connector, P/N 6X09737717 KIT.

Courtesy of Identifix.

The following two tabs change content below.
Underhood Service Staff Writers

Underhood Service Staff Writers

Underhood Service Staff Writers

Latest posts by Underhood Service Staff Writers (see all)

Latest articles from our other sites:

Redline Detection Seeks Nominations for 2nd Annual Redline Rock Star Performance Award

Redline Detection is encouraging anyone who works with, or knows, a talented technician to nominate him or her for the second annual Redline Rock Star Performance Award. The award recognizes a technician...More

Hunter’s Quick Tread Produces Fast, Accurate Tread Depth Readings

Hunter Engineering Company announces its new Quick Tread drive-over tread depth system, which uses point cloud technology to automatically measure the tread depth of each tire without a time loss....More

When Timing Is Everything: A Look At The 2.5L, 2.0L Powerplants

Last month, we looked at the timing chain setup on the Audi 3.2L engine and saw how a lack of oil changes can adversely affect the tensioners and cause engine failure. We’ve also seen similar issues...More

Modern Charging Systems: Cover All The Bases During the Diagnostic Process

To quote a familiar situation: “My customer’s car is now on its third alternator in six months and my jobber store refuses to ­warranty a fourth.” In other words, the parts supplier believes...More

Your Guide to the Kia Brake Job

Kias will provide little challenge for any tech currently handling basic brake work. All it takes is paying attention to details and good work habits to make it profitable. An occasional long pedal...More

Toyota Avalon Alignment Spec: 2005-‘11

The Toyota Avalon is sometimes called the “Japanese Buick” due to its size and plush ride. However, the Avalon’s overall suspension design does not vary that much from Toyota’s smaller vehicle...More

Redline Detection Seeks Nominations for 2nd Annual Redline Rock Star Performance Award

Redline Detection is encouraging anyone who works with, or knows, a talented technician to nominate him or her for the second annual Redline Rock Star Performance Award. The award recognizes a technician...More

Hunter’s Quick Tread Produces Fast, Accurate Tread Depth Readings

Hunter Engineering Company announces its new Quick Tread drive-over tread depth system, which uses point cloud technology to automatically measure the tread depth of each tire without a time loss....More