HEATER FAN BLOWER MOTOR TANDEM RESISTOR

HEATER FAN BLOWER NOT WORKING

With Winter looming in the Northern Hemisphere and Summer looming in the Southern Hemisphere, our car air conditioners are going to be in big demand very soon. On a really hot day the temperature down here in the Cape can easily rise to 35 degrees celsius and the inside of any car would be roughly 3-4 degrees more. That's the kind of discomfort nobody has signed up for. The converse is just as true, I remember when I was in Germany a few years back, during November the temperature dropped right down to minus 24 degrees celsius and whilst in France it was around minus 4 degrees or less most mornings. Trying to brave such weather conditions without on-board creature comforts borders on insane. So while the temperatures hasn't peaked yet, there is still time to get your fan/blower fixed. 

Of late, somehow several VW, Audi, Seat and Skoda owners have been having issues with the fan/ac/blower not working or not working properly. On a previous blog I failed to add the fan/blower issue to the list of common problems, but believe me it is. Below are some questions asked by a few VW owners regarding their respective VW vechicle refering to the fan/AC/Blower motor.  Well the culprit is normally the Heater Fan Blower Motor Tandem Resistor with OE/OEM Number 6Q0959263A / 6Q0959263/6Q0 959 263 A, manufactured by Hans Pries. Alternatively the Hella brand replacement part with  part number 5HL 351 321-301 or 5HL351321-301. 

The speed of the 12V blower motor is controller via this series "blower resistor". It's a wire wound ceramic resistor and it does get quite hot on speeds position 1, 2 and 3. In the last position the resistor is bypassed. So if you blower isn't working on every speed it is most likely the resistor. However if you have an A/C with  a four speed switch and the blower doesn't work on any of its 4 positions, then its most likely the ground wire that's loose, burnt, poor contact, intermittent. Look behind the fan switch, there is a large 4 pin white molex connector and when its ground wire overheats, it looks discoloured, sort of lightly toasted and sometimes makes intermittent contact. On some models the motor is electrically isolated, so connect a jumper between the car body and motor earth, just to test. If the connector is faulty, the motor with spin. If it doesn't spin, check for 12V DC supply on the Red/White wire with a multimeter, if there is no supply voltage, check the fuse and the heater relay. 

BLOWER SWITHC CONECCTIONS

Red/Black - 12V supply to switch from fuse/relay box
Black/White - position 1
Yellow/Black - position 2
Yellow - position 3
Brown - from blower motor to ground/earth

Red/white - 12V supply 
Blue - position 1
Green - position 2
Black - position 3
Red - position 4 
Brown - from blower motor to ground/earth

Blower motor series resistor can be found in the glove compartment on some models

Question:

My heater fan doesn't seem to be working properly, I can feel a small amount of air blowing but I don't hear the blower motor. Please help me!

Answer: 

Read the blog!

Question:

Just bought an Audi A2 2005 and discovered defroster/heat/AC doesn't work. Is this major or should I cancel the sale? 

Answer: 

Read the blog! 

Question:

I have problem with my Jetta fan/blower that stops working, it just switched off after only owning car for two months.  No DTC codes!

Answer: 

Read the blog!

Question:

I recently noticed my interior heater/fan was becoming weak, and stops altogether at low speeds. Must I replace the motor.

Answer: 

Its very likely that the motor brushes has reached end of life. I think a new pair will give you blower a new lease on life. You didn't indicate what car you have, because yours  motor can possibly be of the  sealed type, meaning you would have to replace the motor if and only if you've exhausted the above.

Question:

My Golf's fan/blower works OK, but  after a while it makes a really loud noise like its struggling to keep turning and then it switches off. However when I hit a speed bump in the road it gives me a fright when it just turns back on. Can you help?

Answer: 

Read the blog!

Question:

Just bought a VW caddy and the fan/blower seems lazy and makes a noise that varies between loud and quite, previous owner says there is a leaf that fell down the ducting and lying on the fan. I'm not convinced because sometimes when I turn on the blower, it doesn't blow at all. Any suggestions?

Answer: 

Read the blog!

The heater fan blower motor resistor is one of those items that works on a great many VW, Audi, Skoda and SEAT cars. The list below gives you some idea  how common the problem really is. When you suspect that your heater fan thermal resistor has gone faulty make certain the part number is the same as the one you replacing it with because there is a fair amount of variation  even though there is a degree of compatibility.

Audi, SEAT, compatibility list

SEAT and Skoda compatibility list

SEAT, Skoda and VW compatibility list.


AUDI A2 (8Z0) 1.2 TDI, AUDI A2 (8Z0) 1.4, AUDI A2 (8Z0) 1.4 TDI,  
AUDI A2 (8Z0) 1.4 TDI,  AUDI A2 (8Z0) 1.6 FSI,  


SEAT CORDOBA (6L2) 1.2,  SEAT CORDOBA (6L2) 1.2 12V,  
SKODA FABIA (6Y2) 1.0,  SKODA FABIA (6Y2) 1.2,  SKODA FABIA (6Y2) 1.2,  
VW FOX (5Z1) 1.2,  VW FOX (5Z1) 1.4,  VW FOX (5Z1) 1.4 TDI,  VW POLO (9N ) 1.2,  

SEAT CORDOBA (6L2) 1.4 16V,  SEAT CORDOBA (6L2) 1.4 16V,  
SEAT CORDOBA (6L2) 1.4 16V,  SEAT CORDOBA (6L2) 1.4 TDI,  
SEAT CORDOBA (6L2) 1.4 TDI, SEAT CORDOBA (6L2) 1.4 TDI,  
SEAT CORDOBA (6L2) 1.6, SEAT CORDOBA (6L2) 1.6 16V,  
SEAT CORDOBA (6L2) 1.9 SDI,  SEAT CORDOBA (6L2) 1.9 TDI,  
SEAT CORDOBA (6L2) 1.9 TDI,  SEAT CORDOBA (6L2) 2.0,  
SEAT IBIZA IV (6L1) 1.2 12V,  SEAT IBIZA IV (6L1) 1.4 16V,  
SEAT IBIZA IV (6L1) 1.4 TDI,  SEAT IBIZA IV (6L1) 1.4 TDI, 
SEAT IBIZA IV (6L1) 1.6 16V,  SEAT IBIZA IV (6L1) 1.8 T Cupra R,  
SEAT IBIZA IV (6L1) 1.9 TDI Cupra R,  SEAT IBIZA IV (6L1) 1.9 TDI Cupra R,  
SEAT IBIZA V (6J5) 1.2,  SEAT IBIZA V (6J5) 1.4,  
SEAT IBIZA V (6J5) 1.4 TDI,  SEAT IBIZA V (6J5) 1.9 TDI,  
SEAT IBIZA V (6J5) 1.9 TDI,  SEAT IBIZA V SPORTCOUPE (6J1) 1.2,  
SEAT IBIZA V SPORTCOUPE (6J1) 1.4,  SEAT IBIZA V SPORTCOUPE (6J1) 1.4 TDI,  
SEAT IBIZA V SPORTCOUPE (6J1) 1.9 TDI,  SEAT IBIZA V SPORTCOUPE (6J1) 1.9 TDI,  

SKODA FABIA (6Y2) 1.4,  SKODA FABIA (6Y2) 1.4 16V,  SKODA FABIA (6Y2) 1.4 16V,  
SKODA FABIA (6Y2) 1.4 TDI,  SKODA FABIA (6Y2) 1.4 TDI,  
SKODA FABIA (6Y2) 1.4 TDI,  SKODA FABIA (6Y2) 1.9 SDI,  
SKODA FABIA (6Y2) 1.9 TDI,  SKODA FABIA (6Y2) 1.9 TDI RS,  
SKODA FABIA (6Y2) 2.0,  SKODA FABIA 1.2,  SKODA FABIA 1.2,  
SKODA FABIA 1.4,  SKODA FABIA 1.4 TDI,  SKODA FABIA 1.4 TDI,  
SKODA FABIA 1.6,  SKODA FABIA 1.9 TDI,  SKODA FABIA Estate (6Y5) 1.2,  
SKODA FABIA Estate (6Y5) 1.2,  SKODA FABIA Estate (6Y5) 1.4,  
SKODA FABIA Estate (6Y5) 1.4, SKODA FABIA Estate (6Y5) 1.4 16V,  
SKODA FABIA Estate (6Y5) 1.4 16V,  SKODA FABIA Estate (6Y5) 1.4 16V,  
SKODA FABIA Estate (6Y5) 1.4 TDI,  SKODA FABIA Estate (6Y5) 1.4 TDI,  
SKODA FABIA Estate (6Y5) 1.4 TDI,  SKODA FABIA Estate (6Y5) 1.9 SDI,  
SKODA FABIA Estate (6Y5) 1.9 TDI,  SKODA FABIA Estate (6Y5) 2.0,  
SKODA FABIA Estate 1.2,  SKODA FABIA Estate 1.2,  
SKODA FABIA Estate 1.4,  SKODA FABIA Estate 1.4 TDI,  
SKODA FABIA Estate 1.4 TDI,  SKODA FABIA Estate 1.6,  
SKODA FABIA Estate 1.9 TDI,  SKODA FABIA Praktik 1.2,  
SKODA FABIA Praktik 1.2,  SKODA FABIA Praktik 1.4,  
SKODA FABIA Praktik 1.4 TDI,  SKODA FABIA Praktik 1.9 SDI,  
SKODA FABIA Saloon / Sedan (6Y3) 1.2,  SKODA FABIA Saloon / Sedan (6Y3) 1.2,  
SKODA FABIA Saloon / Sedan (6Y3) 1.4,  SKODA FABIA Saloon / Sedan (6Y3) 1.4,  
SKODA FABIA Saloon / Sedan (6Y3) 1.4 16V,  SKODA FABIA Saloon / Sedan (6Y3) 1.4 16V,  
SKODA FABIA Saloon / Sedan (6Y3) 1.4 16V,  SKODA FABIA Saloon / Sedan (6Y3) 1.4 TDI,  
SKODA FABIA Saloon / Sedan (6Y3) 1.4 TDI,  SKODA FABIA Saloon / Sedan (6Y3) 1.4 TDI,  
SKODA FABIA Saloon / Sedan (6Y3) 1.9 SDI,  SKODA FABIA Saloon / Sedan (6Y3) 1.9 TDI,  
SKODA FABIA Saloon / Sedan (6Y3) 2.0,  SKODA ROOMSTER (5J) 1.2,  
SKODA ROOMSTER (5J) 1.2,  SKODA ROOMSTER (5J) 1.4,  
SKODA ROOMSTER (5J) 1.4 TDI,  SKODA ROOMSTER (5J) 1.4 TDI,  
SKODA ROOMSTER (5J) 1.6,  SKODA ROOMSTER (5J) 1.9 TDI,  

VW POLO (9N ) 1.2,  VW POLO (9N ) 1.2 12V,  VW POLO (9N ) 1.2 12V,  
VW POLO (9N ) 1.4 16V,  VW POLO (9N ) 1.4 16V,  VW POLO (9N ) 1.4 16V,  
VW POLO (9N ) 1.4 FSI,  VW POLO (9N ) 1.4 TDI,  VW POLO (9N ) 1.4 TDI,  
VW POLO (9N ) 1.4 TDI,  VW POLO (9N ) 1.6 16V,  VW POLO (9N ) 1.8 GTI,  
VW POLO (9N ) 1.8 GTi Cup Edition,  VW POLO (9N ) 1.9 SDI,  VW POLO (9N ) 1.9 TDI,  
VW POLO (9N ) 1.9 TDI,  VW POLO Saloon / Sedan 1.4,  VW POLO Saloon / Sedan 1.4,  
VW POLO Saloon / Sedan 1.4 TDI,  VW POLO Saloon / Sedan 1.9 SDI,


VW Golf 3 blower resistor
VW Amrok blower resistor
VW Sharan blower resistor
VW Touareg blower resistor
VW Touareg blower resistor
VW Polo blower resistor
VW Audi blower resistor
VW Fabia blower resistor
VW Ibiza blower resistor
VW Passat blower resistor
VW Skoda blower resistor
VW Seat blower resistor
VW Transporter blower resistor
VW Transporter blower resistor

6Q0959263A / 2D0959263 / 1K0959263A / 701959263B / 701959263D / 7L0907521B / 7L0907521 / 7L0907521A / 7L0907521B / 701959263A / 3C0907521E / 3C0907521F 1K2820015F / 6Q2907521B / 8D1820021 / 1J0819022 / 8K0820521B / 1J0819022A
74024583 / 8D0959263 / 1JO907521 / 1J0819022A 7E0959263C / 6Q0959263A / 

1J0819022A / 

HOW TO FIX AN EPC PROBLEM - CONTINUED

HOW TO FIX AN EPC PROBLEM, - CONTINUED

The final note on the preceding blog installment ended on 'scan for Diagnostic Trouble  Codes with a scan tool'. However before we start scanning it is important to note, that Vehicles from year 2000 are fitted with an EPC (Electronic Power Control) system, hence this exposée only applies to cars fitted with a obdii 16 pin female connector, identifiable by its  normally purple core, roughly the same purple of the 6-pin mini-DIN connector  of a personal computer keyboard.  This EPC system / Drive-by-Wire circuit (implying no throttle cable) is also known as the torque circuit. The EPC system controls the EPC light  which turns on if and when there is the slightest malfunction  in the Drive-by-Wire circuit. Any such fault will more than likely generate a DTC (fault code) in the ECM, which is stored in its non-volatile memory, meaning even if the battery is disconnected afterwards the DTC (fault codes) will persist. However, also note that when the battery is disconnected all driver learnt values particular to your driving style, will be erased. Disconnecting the battery may require resetting the convenience electronics, such as alarm, interior lights and the radio. So, most importantly if you don't have the radio code, practice caution because the radio will permanently lock-up hence it's a good idea to use a jumper battery or perhaps even a battery charger to maintain battery power whilst replacing a battery. Or get the code from your service center.

Whilst any problem in the torque circuit is  normally responsible for turning on the EPC light,  the EPC light may also turn on for some other non-emission related engine faults.  When a combination of emission-related and EPC-related fault is encountered, both the MIL and EPC lights may turn on. This alone give one a good idea of whether or not the engine problem is purely torque related or part of an emission-relate issue.

Most pure torque circuit EPC faults are accompanied by Limp-Home Mode which revolve around the basic settings for the Electronic Throttle Control Valve Adjuster, Idling Control, EPC Adaptation and the  Accelerator Pedal Position Senders. Their values are stored in the ECU normally from group 60 - group 62 of the Bosch ME 7 and newer ECUs, however the actual group may vary subject to make, model and engine capacity of the vehicle. For example. Jetta, Polo, Audi TT, etc, EPC adaptation exists at group 060 - group 062, whereas these values may be stored in group 098 for some VW Passat and Audi A4, S4, B5.

Group=060, Adaptation Epc-system
Group=061, Epc-system (1)
Group=062, Epc-system (2)

Emergency Running or Limp-Home Mode

Both Bosch Motronic and Siemens Simos ECU have two emergency running modes to compensate for accelerator pedal sender failure. The first mode triggers when the primary sender G79 (Sender -1) accelerator pedal sender fails, and the second mode triggers when both G79 and G185 (Sender -2- redundant sender) accelerator pedal senders fail. In the first case with one accelerator pedal sender failing, the accelerator position is limited to a predefined value (limp mode) idling speed while some comfort functions will be disabled,  the Air Conditioner for example. By which time EPC light would have already illuminated. However, when the second emergency mode triggers the engine runs only at idle speed. It would be exactly like disconnecting / removing the accelerator pedal completely. On the occasion that I replaced my accelerator pedal, I started the engine and to my surprise it started perfectly normal and idled at a normal rev. So the conclusion is when both accelerator pedal senders / potentiometer fail, it gives you the same, exact, identical symptoms of a physical steel accelerator cable that snapped. Considering a throttle cable is the single most important part of the throttle system in a car engine. So when it breaks the car will idle, but will not rev. The EPC system mimics the pysical cable exactly or as near as dammit.

Siemens Simos ECU J361 with pin connections

Looking at the diagram for accelerator pedal senders G79 and G185, pins 50 and 19 are inputs from their respective highside driver 5V supplies with pins 18 and 45 of the ECU microprocessor are their independent internal earth connections. The two variable voltages at pins 51 and 64 are the inverse of on another. Essentially G185 (secondary) is working as a backup to G79 (primary). Inputs at pins 51 and 64 are constantly monitored by the ECU microprocessor could range from sporadic to too high or too low, to intermittent to absolutely not there. The  ECU microprocessor with its built-in Watchdog Supervision Safety Logic monitoring performing plausability checks for voltage regulation, Over/Under voltage levels, intermittent voltage levels. If for any reason that the calculations based on its internal algorithms do not correspond to its internally stored and expected values either the watchdog processor or the  Main Processing Element enable   a secondary shutdown path to all equipment under its control. In a nutshell, limp mode.

Constant movement of the gold plated contacts on the potentiometer slider eventually wears through and becomes intermittent especially if the vehicle has attained a high millage, considering  how may times the accelerator pedal has been stepped-on and released. It can be roughly compared to a volume control that's gone scratchy from constant use, when it finally worked through its carbon track and makes intermittent contact.  I've known physical  steel throttle cable to last a lot longer than its electronic counter part but they do have a tendency to fray and get stuck inside its sleeve especially when going at high speed, which is kinda dangerous -even life threatening.  With the EPC system this will not happen, rather if the "electronic steel threads fray" the microprocessor shuts the system down by switching over to its stored alternative values.

Looking at the diagram for G188 and G187 it can clearly be seen that they share a common 5v supply (pin 91) and a common earth (pin97) with the outputs from pins 90 and 92 acting as inputs to the ECU microprocessor that control for the throttle valve actuator motor. These inputs are also constantly monitored by the ECU main Processor and its companion watchdog processor. Noting once again that G188 and G187 act as angle sensors much like that of the accelerator position senders. The concept and principal is exactly the same as that for the accelerator potentiometers. When any discrepancy is detected, a shutdown path is enabled which presents itself to the motorist as a car that won't rev. Then there is G61, the knock sensor. Any  knock higher or vibration outside of that expected by the ECU on pin 102 will also enable a shutdown path and sequence limp mode. 

Accelerator 6 pin plug and harness for VW, Golf, Skoda, Fabia, Audi etc.

Accelerator Pedal 6 Pin Plug Connector Wiring Harness for VW, Amarok, Beetle, Eos,
Lupo, Polo,Touareg, Sharan, Transporter, Electronic  - 3B0 972 706

Based on this, the inputs and outputs from these three components are vital to the correct functioning of any Drive-by-Wire vehicle. So when a fault occurs and guided by error codes, it is important to ensure that there is wired continuity between these components and the ECU connector. Wiring harnesses are subjected to a fair amount of shaking and can break inside of the PVC sleeving. Especially sensitive is the 6 pin Electronic Accelerator Pedal Plug Connector Wiring Harness for VW Polo, Golf, Audi, Skoda, Fabia. VW part number - 3B0 972 706. This replacement part needs to be soldered onto the  wiring harness after cutting off the original plug.