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

Head Gasket Do’s and Don’ts

DO: Clean the holes. To ensure accurate torque values and to avoid cracking the cylinder block, clean any dust, dirt, oil and fluid from the cylinder block head bolt holes before installing the new head gasket and head bolts. Never lubricate the...

Read more...

Harmonic Dampeners: Why They Fail, What to Look For

Every time a cylinder fires, the crankshaft speeds up a very small amount for a short period of time. It is then slowed down as the next cylinder in the firing order compresses air and fuel for the next combustion event. The speeding up and slowing...

Read more...

Be Careful When Replacing That Diesel Air Filter

Modern passenger and light-duty diesels with ECMs have mass airflow sensors and precisely control fuel ­delivery. Key to the efficiency and lifespan of the diesel engine is the diesel air filter. A restricted air filter will not affect fuel economy but...

Read more...

Strange Requests At The Service Counter

Sometimes, I have to wonder if certain ­customers’ brains are firing on all cylinders. But as an automotive service professional, I have to maintain a certain level of self-control while answering their questions, even though what they’re...

Read more...

Are All Cars ‘Supercars’ Now?

I attended an open house at Smokey’s Dyno in Akron, Ohio, last month. The shop was filled with Lamborghinis, Jaguars and other high-end cars. It was a great chance to look under the hoods of some supercars. The shop even had a rare McLaren P1 sitting...

Read more...

Documenting Inspections: Are You Leaving Maintenance Dollars on the Table?

How do you translate scribbles on a ­repair order into sales? There is no magic trick involved — the key is to document the vehicle ­inspection process. The more you know about your customers’ vehicles, and the more you are able to document...

Read more...

TPMS Service Tip: Ask the Right Questions

If there is one piece of major advice for any tire tech facing a TPMS issue, it would be this: Test before you touch, and document the answers you get. Understanding the potential TPMS land mines can save time and money and eliminate frustrations. Get...

Read more...

False ABS Activation After Wheel Bearing Hub Replacement

Vehicles: All ABS-equipped vehicles Condition: Vehicle had wheel bearing hub replaced on one side. Repair Procedure: If you diagnose a bad hub bearing on one side of a vehicle and the ABS wheel speed sensor or tone ring is integral to the bearing,...

Read more...

Are you afraid of selling alignments?

I am starting to notice a trend when it comes to alignments. It’s not the vehicles that are changing, but rather the attitudes toward alignment services — and it happens at independent repair shops, franchise shops and even dealers. The alignment...

Read more...

iATN Exceeds 2 Million Forum Messages

The number of messages in the professional automotive discussion forums of the International Automotive Technicians Network (iATN) exceeded 2 million in early December 2014, with the Shop Management and Technical Discussion forums being the most popular...

Read more...

Diagnosing Starter Misses

Contributing writer Gary Goms was called to a friend’s shop to help with a no-cranking condition on a 2006 Chevy Tahoe. After diagnosing a faulty PCM ground, locating the missing ground proved to be problematic. Find out how Gary solves The Case...

Read more...

Snap-on Adds Diagnostic Calculator To Website

Snap-on announces a new diagnostic calculator feature has been added to its website at http://diagnostics.snapon.com to help automotive repair technicians and shop owners determine how much profit they could be making by using a Snap-on diagnostic platform,...

Read more...

Home European Audi/ Volkswagen Tech Tip: Jetta’s A/C is Not Working; No Power to the A/C...

Print Print Email Email

From the Identifix Direct-Hit Hotline Archives

Customer Concern: The A/C is not working. No power to the A/C clutch. The A/C compressor clutch does not engage. Manual climate control.

Vehicle Applications: 2000 Volkswagen Beetle 2.0L, GAS, Eng Des AEG; 2000 Volkswagen Jetta GL 2.0L; and 2003 Volkswagen Jetta GLS 2.0L, Eng Cfg L4, Eng Des AVH

Tests/Procedures:
Test Fan Control (FC) module inputs as follows:
1. All tests are performed with the ignition key and A/C switched on and the connecters connected to the fan module. The fan control module is located under the radiator and has two connectors: a 14-pin and a 4-pin.

2. Verify approximately 35% duty cycle from the A/C pressure sensor at pin T14/2 (white) with the ignition on but the compressor not running (duty cycle will increase as the high-side pressure increases). A duty cycle above 90 or below 20 will command the compressor off and would indicate a faulty pressure sensor if the compressor is not running and the refrigerant levels are normal. This is a ground-side duty cycle. If the meter is hooked to ground, expect to see 70%.

3. Verify the presence of an 11-volt reference voltage at pin T14/3 (green). The powertrain control module (PCM) 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.

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), when the ignition is in the on position.

8. Verify the presence of an 11-volt reference 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 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. 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.

12. If all tests pass, the fan control module is faulty and must be replaced.

Potential Causes: Malfunctioning A/C switch, air conditioner high pressure sensor, defective fan
control module, ground, power and/or throttle basic settings.

Note: Pin T14/3 will be grounded by the PCM if the throttle basic settings are lost. 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, Inc.

The following two tabs change content below.
ImportCar Staff Writers

ImportCar Staff Writers

Latest articles from our other sites:

Head Gasket Do’s and Don’ts

DO: Clean the holes. To ensure accurate torque values and to avoid cracking the cylinder block, clean any dust, dirt, oil and fluid from the cylinder block head bolt holes before installing the...More

Harmonic Dampeners: Why They Fail, What to Look For

Every time a cylinder fires, the crankshaft speeds up a very small amount for a short period of time. It is then slowed down as the next cylinder in the firing order compresses air and fuel for the next...More

Head Gasket Do’s and Don’ts

DO: Clean the holes. To ensure accurate torque values and to avoid cracking the cylinder block, clean any dust, dirt, oil and fluid from the cylinder block head bolt holes before installing the...More

CARDONE Innovation Team Announces New Products

CARDONE Industries has introduced several new products to its portfolio of automotive replacement parts. Electronic braking units have been added to the company’s remanufactured brakes offering. According...More

TPMS Service Tip: Ask the Right Questions

If there is one piece of major advice for any tire tech facing a TPMS issue, it would be this: Test before you touch, and document the answers you get. Understanding the potential TPMS land mines can...More

False ABS Activation After Wheel Bearing Hub Replacement

Vehicles: All ABS-equipped vehicles Condition: Vehicle had wheel bearing hub replaced on one side. Repair Procedure: If you diagnose a bad hub bearing on one side of a vehicle and the ABS wheel speed...More

iATN Exceeds 2 Million Forum Messages

The number of messages in the professional automotive discussion forums of the International Automotive Technicians Network (iATN) exceeded 2 million in early December 2014, with the Shop Management and...More

Loosen Seized Fasteners with Lisle’s Small Fastener Remover

Use Lisle’s Small Fastener Remover (60530) with a pneumatic impact tool to loosen rusted or seized fasteners. A 3/4" open end wrench can be used to turn the socket while impacting the fastener. A...More