Fabia 1 heater stuck on hot

[sparky2]

:'( Hi all, I still have a problem with the heater on my wifes Fabia (2002) TDi, if it turns up from anything above cold it gives out full heat , I have done some searches on the forums and I have reset the flaps to basic settings and also scanned for any faults, also cleaned the fan motor but this only controls the direction of the air in the cabin with the flaps, what controls the heat side of things ? cheers - Stuart.

[rodit]

:'( Hi all, I still have a problem with the heater on my wifes Fabia (2002) TDi, if it turns up from anything above cold it gives out full heat , I have done some searches on the forums and I have reset the flaps to basic settings and also scanned for any faults, also cleaned the fan motor but this only controls the direction of the air in the cabin with the flaps, what controls the heat side of things ? cheers - Stuart.

Have the same problem on my partners fabia as well as having fitted a new egr valve and reseting base settings only for light to be back on after 20 mile's.

Will be interested to see any answers on your as our's is a 51 plate.

[sparky2]

Sounds like yours is a differant fault as mine has no warning lights coming up, the EGR valve is for the engine, what light is coming on ?

[rodit]

Sounds like yours is a differant fault as mine has no warning lights coming up, the EGR valve is for the engine, what light is coming on ?

I think it will be the same thing.

The light has been an ongoing issue previously to this, it's insuficient flow to egr valve which has been changed but but my searching for that on the forum is not helping.

Hope the heater isue get's answered.

[sparky2]

Hi welcome to the forums (just noticed 1st post), I presume your Rod ? where abouts are you in the country ? you could do with a VCDS scan on the car to see if the ECU has logged any faults,have you tried cleaning the pipes that go to the EGR valve ? Your best bet is to put as much info on the car as possable in the post so that others can diagnose the fault. cheers - Stuart

[rodit]

Hi welcome to the forums (just noticed 1st post), I presume your Rod ? where abouts are you in the country ? you could do with a VCDS scan on the car to see if the ECU has logged any faults,have you tried cleaning the pipes that go to the EGR valve ? Your best bet is to put as much info on the car as possable in the post so that others can diagnose the fault. cheers - Stuart

Cheers Stuart.

I am TIM, Rodit comes from messing around with hot rod's too much.

I best start a new thread for the egr thing as not wanting to clog up someone else's request which also relates to another fault the car has.

Thanks for the welcome.

[Kablam]

At the base of the control unit (where the twisty nobs are for speed, temp etc) there is a small grill type thingamy. Anyway behind that there's the temp sensitive resistor, this can get clogged with dust, the result of which is that you will get no gradating scale of temperature, but either cold (on the coldest temp) or hot (everything else).

This information I think is accurate, but was written after a number of beers

[sparky2]

Thats OK, i am having a beer myself so I take it this temp sensor (thermistor) is a common fault ? is it easy to get too ? cheers - Stuart

[grr666]

I always thought it was a very basic climate control system.

So it blows warm until the cars interior is up to set temperature then reduces in

temperature to maintain the setting...

If the car is only used for very short journeys this may be why it always seems

to blow hot. On a longer run it usually stabilises and reduces the warmth of the blown air.

But if the internal sensor is clogged/blocked with fluff or whatever as Kablam suggests

that may possibly be your issue.

To gain access to said sensor.

Using something like a thin butter knife carefully pry the plastic fascia panel off of the

heater control unit inside the cabin and give it a good old suck out with the hoover.

Snap cover back on and see if it's any better.

Edited 27 September, 2010 by grr666

[kite232]

Have the same problem on my partners fabia as well as having fitted a new egr valve and reseting base settings only for light to be back on after 20 mile's.

Will be interested to see any answers on your as our's is a 51 plate.

Hi I have the same prob with my 52 plate 1.9tdi estate. I am going to have to sort out. The problem is almost certainly either the thermister or the flap control motor or both. If the thermister clean the only certain way to eliminate it is to change it, the flap control motor is a common fault and a bit difficult to get at and fiddly to engage gears in the correct position. The EGR valve has no connection with the heater system.

[Clunkclick]

My Fabia saloon has the same problem.

Temperature flap motor sticks or occasionally overrides the dashboard temperature setting, typically outputing hot when you want cold.

I understand that replacing the motor and resetting all the components in the correct position is fiddly (I posted an Elsa Win diagram a little time ago - can't find it now !)

For what its worth, I 've found that a temporary fix can be obtained by GENTLY rotating the dashboard temperature control back and forth between the minimum and maximum temp settings. Sometimes this frees up the motor and it starts working again properly again. Also, leaving the temperature control at the mid-way setting before switching off the air-con/fan tends to lead to the thing working correctly on next use.

http://briskoda.net/forums/topic/162811-aircon-not-what-it-used-to-be/page__p__2004359__fromsearch__1entry2004359

http://briskoda.net/forums/topic/171996-fabia-heat-output/page__p__2085260__fromsearch__1entry2085260

Nick

Nick

[DRJ]

I always thought it was a very basic climate control system.

So it blows warm until the cars interior is up to set temperature then reduces in

temperature to maintain the setting...

If the car is only used for very short journeys this may be why it always seems

to blow hot. On a longer run it usually stabilises and reduces the warmth of the blown air.

Precisely! My 2004vRS was like that since new - and my 2007vRS is exactly the same.

That's how it's SUPPOSED to operate...

[sparky2]

Sorry lads but this sticks on full blast and won't switch down, the only way sometimes is to stop and turn the engine off for a couple of minutes. It looks as though the V68 Flap Motor is faulty/stuck which is behind the lower dash panels.I am just looking for a way of getting to it. cheers - Stuart

[Clunkclick]

Precisely! My 2004vRS was like that since new - and my 2007vRS is exactly the same.

That's how it's SUPPOSED to operate...

Nein, Nein, Nein, Nein.

There's climate control on the elegance models and VRS and simple air conditioning on the rest. I thought the climate control had a digital control on it.

Neverthe less, there is a wide spread and well known fault with the temperature flap sticking. My simple air conditioning system will also, unprompted, suddenly blow hot air when the dashboard selector is on cold and then ,equally quickly, revert to the correct temperature. This is an electrical/motor fault and shows up as such on the VAG COM diagnostic report, I think its V154 - temperature control flap - followed by the error code. Simple air con systems are not supposed to do that. They are supposed to consistently deliver the dialled-up temp irrespective of the cabin temperature. Climate control systems are diffrent.

Nick.

[DRJ]

Nein, Nein, Nein, Nein.

There's climate control on the elegance models and VRS and simple air conditioning on the rest. I thought the climate control had a digital control on it.

Neverthe less, there is a wide spread and well known fault with the temperature flap sticking. My simple air conditioning system will also, unprompted, suddenly blow hot air when the dashboard selector is on cold and then ,equally quickly, revert to the correct temperature. This is an electrical/motor fault and shows up as such on the VAG COM diagnostic report, I think its V154 - temperature control flap - followed by the error code. Simple air con systems are not supposed to do that. They are supposed to consistently deliver the dialled-up temp irrespective of the cabin temperature. Climate control systems are diffrent.

Nick.

No, no, no, no

"There's climate control on the elegance models and VRS and simple air conditioning on the rest. I thought the climate control had a digital control on it."

No - the vRS has the "simple" system - it has an AC button and a temperature calibrated dial for cabin temperature (not air supply temperature) set by a single temperature sensor rather than the multiple sensors in a proper "climate" system. I@m not sure whether this sensor is next to the AC/Recirc. switches or in the overhead light assembly.

"My simple air conditioning system will also, unprompted, suddenly blow hot air when the dashboard selector is on cold and then ,equally quickly, revert to the correct temperature. "

No - the temperature control on the dash isn't a simple hot or cold setting - it's a thermostat showing temperature figures.

My car will blow hot air even when the control is set right down at 18 degC until the cabin is warmed up, when it lessens. This is how a thermostat operates. My car was scanned last week (for other reasons) and no fault codes came up - I wouldn't expect them since the car's operating as the manufacturer designed it to.

I acknowledge that SOME cars might have a connected problem but it doesn't apply to all cars as some people try to suggest...

[sparky2]

:S Well I did a scan last night on the car and it showed 3 faults with the motor flap so I will try and strip it down this weekend, I have had a look around other forums and its a well known motor fault, if I manage to do it I will take a few photos. cheers - Stuart (yr2002 Elegance)

[Clunkclick]

My car will blow hot air even when the control is set right down at 18 degC until the cabin is warmed up, when it lessens. This is how a thermostat operates. My car was scanned last week (for other reasons) and no fault codes came up - I wouldn't expect them since the car's operating as the manufacturer designed it to.

That's the sort of reply Skoda Customer Services would say to muddy the waters. Like all the other niggling problems, one way of avoiding liability is to deny the problems exist. "The king is always fully clothed".

I didn't purchase VAG Com until my vehicle was 2.5 years old from new. And the first time I plugged it in the system showed the temperature flap as a fault code. At the time the air conditioning was operating correctly. Its only started seriously malfunctioning in the last 18 months, so only then did I understand the significance of the fault code. 7 years down the track, obviously, too late now to do anything about it under warranty but it must have shown up on each of the annual services for the last 7 years and dealer took no action.

I thought the simple air conditioners were input temperature based i.e if you selected 18C on the dash board that would be the temperature of the air supplied by the Air/Con system. NOT the cabin temperature.

Climate control systems are output based i.e. you set the desired cabin temperature on the digital selctor and the system operates in a pre-programmed way until it reaches that temperature.

I thought all the more expensive Skoda marques were fitted with climate control systems.

Nick

Edited 2 October, 2010 by Clunkclick

[DRJ]

That's the sort of reply Skoda Customer Services would say to muddy the waters. Like all the other niggling problems, one way of avoiding liability is to deny the problems exist. "The king is always fully clothed".

They did give me the printout...

[DRJ]

I thought the simple air conditioners were input temperature based i.e if you selected 18C on the dash board that would be the temperature of the air supplied by the Air/Con system. NOT the cabin temperature.

Climate control systems are output based i.e. you set the desired cabin temperature on the digital selctor and the system operates in a pre-programmed way until it reaches that temperature.

I thought all the more expensive Skoda marques were fitted with climate control systems.

My understanding of the system - based on information gleaned from this site - is that the "simple" AC system with a temperature graduated dial changes the temperature of the output air to suit the requirement inside the car, but bases this temperature on the output of only one temperature sensor in the cabin, whereas more sophisticated "climate" systems have multiple sensors to create a more accurate/balanced output.

[Clunkclick]

My understanding of the system - based on information gleaned from this site - is that the "simple" AC system with a temperature graduated dial changes the temperature of the output air to suit the requirement inside the car, but bases this temperature on the output of only one temperature sensor in the cabin, whereas more sophisticated "climate" systems have multiple sensors to create a more accurate/balanced output.

Theoretically, an input only aircon system would have an air temperature sensor in the cabin - the occupant. But thinking about it, your right. Whilst there is no energy use penalty in the current VW aircon systems from not having a cabin temperature sensor ('Cause the compressor is always engaged i.e. clutchless) there's got to be some system based cabin temperature regulation, otherwise temperatures would become unbearable for the occupant very quickly and you'd be for ever altering the dashboard setting. to get an acceptable temperature. Reading more more of the VW literature it looks like they only install semi-automatic aircon and full climatronic systems which both have some sort of output temperature regulation relating to the cabin, only difference is that the climatronic system has mutliple temperature senosrs in the cabin so that it can implementa zonal temperature control.

I got a suspicion that the semi automatic systems rely on a deduced/inferential cabin temperature arrangement in order to regulate the cabin temperature. I say this because the only temperature sensor in the cabin I know about is the evapouration temperature sensor behind the dashboard. This was the senos that my dealer replaced when the aircon first started to go wrong. i believe in the Fab model I have there is only one other and that's the outside air temperature sensor that supplies the reading in the instrument binnacle. If temperature sensors in the model I have are limited to these two, then maybe cabin temperature is determined on the following inferential basis i.e sense the outside temperature, sense evapourator temperature, read dash board temperature knob position, and adjust the proportion of outside air admitted to the system to air passing over the air conditioner according to a predetermined formula - if that's not the case that will give the value engineers food for thought.

To be sure, i'm not really certain. I'll check the current flow diagrams on my copy of ELsawin (There's nothing in the Haynes manual).

Postscript.

How wrong I was.

Extracts from Elsawin for my fabia saloon

http://www.flickr.com/photos/54474784@N05/5046473405/

Air conditioning system control unit, fresh air blower, fresh air and recirculated air flap control motor, fuse holder

E9 - Fresh air blower switch

E159 - Fresh air/air recirculating flap switch

G56 - Dash panel temperature sensor

G143 - Fresh air and air recirculation flap control motor potentiometer

J301 - Air conditioning system control unit

K114 - Fresh air/air recirculation warning lamp

L16 - Air conditioning system control illumination

N24 - Fresh air blower series resistor with overheating fuse

T2u - 2-pin connector, at fresh air blower

T4e - 4-pin connector, at fresh air blower series resistor

T5h - 5-pin connector, at fresh air blower switch

T6s - 6-pin connector, on fresh air and air recirculation flap control motor

T10c - 10-pin connector, behind dash panel, right

T18c - 18-pin connector, at air conditioning system control unit

V2 - Fresh air blower

V42 - Temperature sensor blower - dash panel

V154 - Fresh air and recirculated air flap control motor

606 - Earth point, under the centre console, near gear stick

A34 - Positive connection (75x), in wiring harness behind dash panel

L4 - Connection (75al), in air conditioning system wiring harness

L5 - Connection (sender earth), in air conditioning system wiring harness

L31 - Connection (5V), in air conditioning system wiring harness

Looks like there are at least two temperature cabin temperature sensors G56 and V42 , both in the dash panel.

And there's also the other temperature sensors behind the dash, G191, G192 and G263:-

http://www.flickr.com/photos/54474784@N05/5047112708/

Air conditioning system control unit, temperature flap control motor, temperature sender

E35 - Air conditioner switch

G92 - Temperature flap control motor potentiometer

G191 - Vent temperature sender, centre

G192 - Vent temperature sender, footwell

G263 - Evaporator out-flow temperature sender

G267 - Temperature selection rotary knob, potentiometer

J301 - Air conditioning system control unit

K84 - Air conditioning system warning lamp

SB3 - Fuse, in fuse holder

T2h - 2-pin connector, at vent temperature sender, footwell

T2i - 2-pin connector, at evaporator out-flow temperature sender

T2j - 2-pin connector, at vent temperature sender, centre

T6u - 6-pin connector, at temperature flap control motor

T16b - 16-pin connector, in glove compartment on the driver's side (diagnostic connection)

T16e - 16-pin connector, at air conditioning system control unit

T18c - 18-pin connector, at air conditioning system control unit

V68 - Temperature flap control motor

A68 - Positive connection (30a, air conditioning system), in wiring harness behind dash panel

L5 - Connection (sender earth), in air conditioning system wiring harness

L6 - Connection (sender earth), in air conditioning system wiring harness

L31 - Connection (5V), in air conditioning system wiring harness

Nick.

Edited 3 October, 2010 by Clunkclick

[DRJ]

Here's the evidence for the temperature sensor being in the car:

I've had the trim off on the controls.. there's what looks like a temp sensor behind the right hand tiny grille.. mounted on a little circuit board. However, my grille, and all around the sensor was caked in dust and actually, since blowing it all out/away the systems been much more reliable. I tend to have mine all on the screen or screen and feet set at 18'c.. over the last two weeks the temp out side has been up & down... not had to move the temp dial much at all.. maybe one click at most in either direction. ...

[sparky2]

:S Well I stripped down the dash underneath both sides and the motor/actuators are both in the passengers footwell, the one on the left underneath is V154 air control flap and the one on the right hidden behind the cabin filter is V68 temp control flap, I have had both off and had a look at the motors which are supposed to have brushes that wear out, well mine had 3 little fingers that made contact with the commutator and were OK , I did squirt some switch cleaner into the potentiometers as they jumped slightly, I have just put it all back together to see how it behaves. cheers - Stuart

ps - there is a little fan behind the control knobs which draws cabin air past the air temp sensor making it react quicker.

Edited 3 October, 2010 by sparky2

[sparky2]

Update - it looks as though its working at the moment, so fingers crossed xx

[rodit]

Update - it looks as though its working at the moment, so fingers crossed xx

Been doing a bit more hunting on our's.

Seems heaters are blowing cold when set at cold but as soon as adjusted slightly on temp they blow at full hot, even set at 18.

It's a basic set up 1.4 16v comfort, tried cleaning dust from around the thermistor thing by the dials.

Any help really appreciated.

[DRJ]

Seems heaters are blowing cold when set at cold but as soon as adjusted slightly on temp they blow at full hot, even set at 18.

It's a basic set up 1.4 16v comfort, tried cleaning dust from around the thermistor thing by the dials.

Mine does that - but as the cabin heats up the temperature goes down - but it'll take several miles...