Common Audi Issue: No Heat

Make: Audi | Model Example: 2016 A3 Quattro | Avg. Mileage: 118063 | Job Number: 407285

Repair Issue:

No Heat

Cause:

Plugged Coolant Passages – Defective Coolant Thermostat – Contaminated Engine Coolant – Plugged Heater Core – Defective Water Pump

Customer Concern:

The heater is performing poorly and the passenger compartment feels like there is no heat.

Test/Procedure:

1. Verify blend door operation.
2. With a factory compatible scan tool, enter Address Word 08-Air Conditioning. Select Function 04-Basic Settings. Enter Display Group 000 or 001. This is the air distribution flap motor basic setting. The values on the screen will count up then count down and show all “0’s” when completed. If there are no fault codes stored at that point, the blend door is operating correctly.
3. Without a factory compatible scan tool, a visual inspection is required to verify blend door operation.
4. For a heater core to operate correctly, the base cooling system must be in proper working order. Be sure to check the following and correct any concerns as needed:
5. The water pump must be intact (not broken or slipping on it’s splines) and be circulating the coolant through the system. On these VW/AUDI vehicles, the water pump is actually sucking the coolant through/from the heater core. It is not pushing the coolant through. Disconnecting the heater core hose and looking for flow is not a valid test.
6. The thermostat must be properly rated for the vehicle (most VW/AUDI thermostats start to open at approx. 86°C or 187°F). The thermostat must also not be stuck closed creating an overheat condition or stuck open creating an underheat condition.
7. The condition of the coolant is critical to proper cooling system operation. The factory coolant is G12 and is a non-phosphate/non-silicate based coolant. When factory coolant is intermixed with standard type ethylene/glycol based coolants, the chemical reaction starts to solidify and gel up in the cooling system creating restrictions and flow concerns.
8. Proper flow through the cooling system is critical. As a general rule of thumb, the upper coolant return hose to the coolant reservoir is the last hose supplied with coolant. Get the vehicle up to normal operating temperature. At idle, the upper return hose may spit and sputter and little flow will be seen. If the RPM is raised to 3000, there should be a noticeable increase in flow and amount of coolant flowing through that hose. If there is good flow, this is a good indication that the rest of the base (engine) cooling system is free of restrictions and flowing correctly.
9. The radiator must be free of restrictions and flowing freely. Use an infrared thermometer and check the upper and lower hoses for proper temperature difference.
10. The radiator fans must be able to turn on of their own accord. If the fans turn on by themselves, this is a good indication that the radiator is in proper working order.
11. Measure the two heater core hoses at normal operating temperature. With full heat commanded and blower motor on High, I would expect to see roughly a 20-30 degree difference between the hoses. An extremely large difference (60 degrees or so) would indicate a completely plugged heater core that is not allowing flow. A small difference (5 degrees or so) would indicate a partially restricted heater core that is only allowing coolant to flow through a small portion.
12. If the heater core appears to be the cause of concern, backflushing the heater core is an option to try before removing the dash and replacing the heater core. For best results, use a solid detergent that has low foaming and easy rinse characteristics. Dishwasher detergent seems to work the best. Let the heater core soak and use air and water to agitate the heater core when flushing.

Tech Tip

A common characteristic of a partially plugged heater core is varied heat output. If there is good heat while cruising down the road (higher RPM and more flow), but poor heat output at idle (lower RPM and less flow), this strongly indicates that the heater core is restricted and causing the concern.

Important Take-A-Way:

With 12 test procedures listed to help auto technicians, it’s import to know you will need a factory compatible scan tool to accurately diagnose the issue. This could save value time before you even start the process. Knowing you can backflush the existing hearter core instead of removing and replacing the heater core as a last could be a great way to save time and your customer unnecessary expense.

Most Popular Fix:

Replaced/Cleaned/Repaired/Bled Heater Core – Cooling System Flushing Procedure

Other Common Car Problems:

View more common car problems from the most popular manufactures including Ford, Dodge, Chevrolet, Honda, Toyota, and more. Read more

Also applies to the following Makes and Models:

2015 A3 Quattro 2.0, 1998 A4 1.8, 1999 A4 1.8, 2000 A4 1.8, 2001 A4 1.8, 2002 A4 1.8, 2003 A4 1.8, 2004 A4 1.8, 2005 A4 1.8, 1998 A4 2.8, 1999 A4 2.8, 2000 A4 2.8, 1997 A4 Quattro 1.8, 1998 A4 Quattro 1.8, 1999 A4 Quattro 1.8, 2000 A4 Quattro 1.8, 2001 A4 Quattro 1.8, 2002 A4 Quattro 1.8, 2003 A4 Quattro 1.8, 2004 A4 Quattro 1.8, 2005 A4 Quattro 1.8, 2006 A4 Quattro 2.0, 2007 A4 Quattro 2.0, 2008 A4 Quattro 2.0, 1996 A4 Quattro 2.8, 1997 A4 Quattro 2.8, 1998 A4 Quattro 2.8, 1999 A4 Quattro 2.8, 2000 A4 Quattro 2.8, 2001 A4 Quattro 2.8, 2002 A4 Quattro 3.0, 2003 A4 Quattro 3.0, 2004 A4 Quattro 3.0, 2009 A4 Quattro 3.2, 2009 A5 Quattro 3.2, 2003 A6 3.0, 2015 A6 Quattro 2.0, 2000 A6 Quattro 2.7, 2001 A6 Quattro 2.7, 2002 A6 Quattro 2.7, 2003 A6 Quattro 2.7, 2004 A6 Quattro 2.7, 1997 A6 Quattro 2.8, 1998 A6 Quattro 2.8, 1999 A6 Quattro 2.8, 2000 A6 Quattro 2.8, 2001 A6 Quattro 2.8, 2002 A6 Quattro 3.0, 2003 A6 Quattro 3.0, 2004 A6 Quattro 3.0, 2005 A6 Quattro 3.0, 2006 A6 Quattro 3.0, 2007 A6 Quattro 3.0, 2008 A6 Quattro 3.0, 2009 A6 Quattro 3.0, 2010 A6 Quattro 3.0, 2011 A6 Quattro 3.0, 2012 A6 Quattro 3.0, 2008 A6 Quattro 3.2, 1997 A8 Quattro 4.2, 1998 A8 Quattro 4.2, 1999 A8 Quattro 4.2, 2000 A8 Quattro 4.2, 2001 A8 Quattro 4.2, 2002 A8 Quattro 4.2, 2003 A8 Quattro 4.2, 2004 A8 Quattro 4.2, 2005 A8 Quattro 4.2, 2006 A8 Quattro 4.2, 2007 A8 Quattro 4.2, 2008 A8 Quattro 4.2, 2009 A8 Quattro 4.2, 2010 A8 Quattro 4.2, 2011 A8 Quattro 4.2, 2012 A8 Quattro 4.2, 2006 A8 Quattro 6.0, 2002 Allroad Quattro 2.7, 2003 Allroad Quattro 2.7, 2004 Allroad Quattro 2.7, 1996 Cabriolet 2.8, 1997 Cabriolet 2.8, 2018 Q3 Quattro 2.0, 2012 Q5 2.0, 2013 Q5 2.0, 2014 Q5 2.0, 2015 Q5 2.0, 2016 Q5 2.0, 2017 Q5 2.0, 2018 Q5 2.0, 2001 S4 2.7, 2002 S4 2.7, 2002 TT 1.8, 2000 TT Quattro 1.8, 2001 TT Quattro 1.8, 2002 TT Quattro 1.8, 2018 Atlas 3.6, 2019 Atlas 3.6, 2000 Beetle 1.8, 2001 Beetle 1.8, 2002 Beetle 1.8, 2003 Beetle 1.8, 2004 Beetle 1.8, 2005 Beetle 1.8, 2006 Beetle 1.8, 2007 Beetle 1.8, 2008 Beetle 1.8, 2009 Beetle 1.8, 2010 Beetle 1.8, 2011 Beetle 1.8, 2012 Beetle 1.8, 2013 Beetle 1.8, 2014 Beetle 1.8, 2015 Beetle 1.8, 2016 Beetle 1.8, 2017 Beetle 1.8, 2000 Beetle 1.9, 2001 Beetle 1.9, 2002 Beetle 1.9, 2003 Beetle 1.9, 2004 Beetle 1.9, 2005 Beetle 1.9, 2006 Beetle 1.9, 1999 Beetle 2.0, 2008 Beetle 2.5, 2010 CC 2.0, 2011 CC 2.0, 2012 CC 2.0, 2007 Eos 2.0, 2002 EuroVan 2.8, 2015 Golf 1.8, 2016 Golf 1.8, 2003 Golf 1.9, 2017 Golf Alltrack 1.8, 2017 Golf SportWagen 1.8, 2015 GTI 2.0, 2014 Jetta 1.4, 2014 Jetta 1.8, 2000 Jetta 1.9, 2001 Jetta 1.9, 2002 Jetta 1.9, 2003 Jetta 1.9, 2004 Jetta 1.9, 2005 Jetta 1.9, 1999 Jetta 2.0, 2000 Jetta 2.0, 2001 Jetta 2.0, 2002 Jetta 2.0, 2003 Jetta 2.0, 2004 Jetta 2.0, 2005 Jetta 2.0, 2006 Jetta 2.0, 2007 Jetta 2.0, 2008 Jetta 2.0, 2009 Jetta 2.0, 2010 Jetta 2.0, 2011 Jetta 2.0, 2012 Jetta 2.0, 2013 Jetta 2.0, 2014 Jetta 2.0, 2015 Jetta 2.0, 2005 Jetta 2.5, 2006 Jetta 2.5, 2007 Jetta 2.5, 2008 Jetta 2.5, 2009 Jetta 2.5, 2010 Jetta 2.5, 2011 Jetta 2.5, 2012 Jetta 2.5, 2013 Jetta 2.5, 2001 Jetta 2.8, 2000 Passat 1.8, 2001 Passat 1.8, 2002 Passat 1.8, 2003 Passat 1.8, 2004 Passat 1.8, 2005 Passat 1.8, 2006 Passat 1.8, 2007 Passat 1.8, 2008 Passat 1.8, 2009 Passat 1.8, 2010 Passat 1.8, 2011 Passat 1.8, 2012 Passat 1.8, 2013 Passat 1.8, 2014 Passat 1.8, 2015 Passat 1.8, 2016 Passat 1.8, 2017 Passat 1.8, 2004 Passat 2.0, 2005 Passat 2.0, 2006 Passat 2.0, 2007 Passat 2.0, 2008 Passat 2.0, 2009 Passat 2.0, 2010 Passat 2.0, 2011 Passat 2.0, 2012 Passat 2.0, 2013 Passat 2.0, 2014 Passat 2.0, 2015 Passat 2.0, 2013 Passat 2.5, 1998 Passat 2.8, 1999 Passat 2.8, 2000 Passat 2.8, 2001 Passat 2.8, 2002 Passat 2.8, 2003 Passat 2.8, 2004 Passat 2.8, 2005 Passat 2.8, 2009 Tiguan 2.0, 2010 Tiguan 2.0

Author: William Krug

Bill started his automotive career at an early age. He attended the small engine class and also spent 2 years in the high school automotive shop learning the basics of automotive repair. He also worked for an independent Goodyear dealer during this time. After graduation, Bill spent 2 years in Chicago completing the Automotive and Ford Fact programs with Universal Technical Institute. After graduation, he then went on to the Audi Academy where he received factory specific training. Bill spent 4 years in North Carolina working as a technician at an Audi dealership;. It was here that he achieved Expert status as a Audi technician while facing the many challenges of automotive diagnosis that today’s cars provide. Bill is currently an Audi/VW specialist with the European Carline.

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