VW 9N HVAC

VW 9N HVAC PROBLEMS

There are hundreds if not thousands of VW owners who have had HVAC (Heating, Ventilation and Air Conditioner) problems, some are still having HVAC problems on a daily basis and those who haven't had HVAC trouble as yet, is sure to encounter them rather sooner than later.  These three functions are often combined into a single system in most modern vehicles and VW Polo 9N owners seemed to be  more affected by a failing HVAC system  than other VW owners in general.   If you've noticed your Polo 9N's temperature gauge misbehaving — randomly going up and down — but not reaching the required  90 deg, then you can expect your aircon/heater to go faulty. The problem with the HVAC is the poor quality of the two flat motors that control the flaps. Since the 9N Polo 2002-2009 are now ageing, thus out of warranty, we can expect more HVAC problems. Though in my opinion 9N HVAC problems should still be repaired under warranty, considering a car fan / air conditioner is only used for short burst at a time, a few times per day for roughly three month a year, so its collective millage is a far cry from the ceiling mounted fan at home that in some cases last a lifetime. Those fan motors just go on forever. But these motors don't spin constantly they only do while they open or closing a flap. Something like a throttle control flap motor.

Be that as it may, the need for a working climatic control system is upon us. For those in Europe or living above the tropic of cancer, it is almost imperative that your HVAC works because Winters can get quite cold up there. However, what's worse than getting cold? You guessed it, it's getting hot! In the Southern Hemisphere during mid summer, the inside of a car can reach or even exceed 50 degrees Celcius. That's the kind of heat very few people can handle without a HVAC. 

VW Polo 9N Air Heater Vent Flap Positioning Motor Square plug /
oval plug 6Q0 907 511 and oval plug 6Q0 907 511-A

HVAC problem are not limited to the temperature 'Flap motor (P/N 6Q0 907 511) and 'Recirculation Motor (P/N 6Q0 907 511C). There is also a fairly troublesome sensor (G65) attached to the  high pressure air hose, on the right side of the engine. The  Klimaanlage X0830 /X0840 / X0850 / Control Module 6Q0 820 045 is also notorious for giving up the ghost. When the Control Module goes faulty or goes offline, a VCDS scan often present an 'Internal Control Module Memory Error'. But before replacing the Control Module, check the wiring to and from the Control Module including the Voltage Supply and make certain there is a solid ground connection. The reason for the 'Internal Control Module Memory Error' is because the Gateway control module stored a checksum for all the on-board modules and when a module goes offline, the parity bit will be different from the stored one and presents itself as  'Internal Control Module Memory Error'. 

Air flow flap positioning motor V71

The problem with this, is that vehicle owners are temped to change the coding of one or more of their control modules just to see what happens. Very importantly, before we continue, I need to stress if you have an urge to do so, make certain that you have a full printout of all the coding values of all the control modules before changing anything. Failure to do so could render your VW Polo unusable because there is no guide or manual that specifically tells you which bit in the coding  does what. Trial and error can brick your car permanently. So take care!

The average HVAC fault can range from a 1 line fault to as many lines in the list below. Normally you would encounter 2 faults, 3 faults  or 4 faults, 5 or 6 faults, 7 or 8 faults at a time, all related to the same system.  When the HVAC goes faulty, it is common to have hot air blowing that cannot be turned down even though the temp control is set to cold (blue). It is just as common to get no warm air at all, even on maximum hot (red). The cause of the problem is the two motorized flaps in the heater system because both motors (V68) and (V154) are somewhat unreliable and tend to jam intermittently. The one motorized flap controls the heat and the other controls the amount fresh air entering the vents. The only way to fix this problem, is to replace both motors but doing so is a huge job because getting to the heater mechanism requires you to remove the dashboard, steering wheel, the airbags and of course the battery before commencing. It is better left for the VW agent but let me remind you that this repair doesn't come cheap.

Address 08: Auto HVAC        Labels: 6Q0-820-045.lbl
   Part No: 6Q0 820 045
   Component: Klimaanlage        X0830 / X0840  / X0850

00705 - Relay for Coolant Fan; Stage 1 (J279)
            31-00 - Open or Short to Ground
00819 - High Pressure Sensor (G65)
            07-00 - Signal too Low
00819 - High Pressure Sensor (G65)
            31-10 - Open or Short to Ground - Intermittent
01271 - Positioning Motor for Temperature Flap (V68)
            41-10 - Blocked or No Voltage - Intermittent
01271 - Positioning Motor for Temperature Flap (V68)
            30-10 - Open or Short to B+ - Intermittent
01271 - Positioning Motor for Temperature Flap (V68)
            29-10 - Short to Ground - Intermittent
01271 - Positioning Motor for Temperature Flap (V68)
            28-10 - Short to Plus - Intermittent
01299 - Diagnostic Interface for Data Bus (J533)
            79-00 - Please Check Fault Codes
01317 - Control unit in dash-J285
            79-00 - read data from memory
01596 - Motor for Outside/Recirculated Air Flap (V154)
            41-10 - Blocked or No Voltage - Intermittent
01596 - Motor for Outside/Recirculated Air Flap (V154)
            41-00 - Blocked or No Voltage
01596 - Motor for Outside/Recirculated Air Flap (V154)
            30-10 - Open or Short to Plus - Intermittent
01596 - Motor for Outside/Recirculated Air Flap (V154)
            30-00 - Open or Short to Plus
01596 - Motor for Outside/Recirculated Air Flap (V154)
            29-10 - Short to Ground - Intermittent
01596 - Motor for Outside/Recirculated Air Flap (V154)
            28-10 - Short to Plus - Intermittent
65535 - Internal Control Module Memory Error
            00-00 - -

There are also a few other motors that may go faulty amongst them are V70  (Central flap control motor) ,V71 ( Fresh/recirculating air flap motor) , V107 (Defroster flap control motor) and lastly V2 the fresh air blower motor.