Aux Heater Temp Sensor

[Ogben Schmutzel]

Hi All,

 

Before I go shorting out the wrong thing has anyone got a piccy of the Aux heater temp sensor they could post please.

 

Or a link to one. Had a look here and can't find one.

 

Cheers.

 

Oggy.

[Jeff115]

No piccy Oggy, but you cannot miss the ambient temp sensor on the wiper arm linkage in the engine compartment and behind the battery.

 

From memory it was made of a copper alloy metal with a blue connector and two cables running to it.

 

You can also test it by spraying it with burn spray i.e. chlling agent to allow current to pass through it.

 

I have not come across anyone that's found it to be faulty?

 

J.

[marinabrid]

i got a oban send me your email and i post it you, i also got new for sale at a fiver

[Ogben Schmutzel]

Martin,

 

Scuse my ignorance, what's an oban?

 

Cheers.

Oggy.

[marinabrid]

sorry o g b e n got it right this time, obans in wales int it ? or is it iceland ?

anyway i got pic if you want or go to ebay in ford car parts i put it on there for sale :)

[seatkid]

The switch (N289) is located near the horns behind/next to the offside foglamp.

[Ogben Schmutzel]

SeatKid,

 

Thanks but that is not the one I meant. I meant the one that is on the wiper linakge.

 

Cheers.

Oggy.

[seatkid]

From what I can work out, the thing near the pollen filter is the Climate control external temperature sensor.

 

As far as I can work out, the booster heater is not linked to the cc unit at all, it is independantly controlled by thermoswitch N289 and its own internal coolant temperature sensor.

 

I may be wrong though.

[GSMGuy]

SK, the one on the wiper linkage is definately for the booster, the one near the foglight is the "other" external temp sensor..

 

Mike

[Masked Marauder]

Circled in the picture. It simply unclips from the arm.

 

Also in the picture to the right is the connector that is plugged into the back of it with a 10A mini-fuse in it!

 

http://www.bigtrucker.co.uk/images/heaterswitch.jpg

[Jeff115]

The ambient temperature switch (F38) located on the wiper linkage and behind the battery:

1. switches on booster heater to heat coolant at temperature less than 10 degrees plus

2. switches off a/c magnetic coupling (clutch) at low ambient temperatures

 

I previosly thought that the temp. sensor at the fog lamp controlled the a/c but there you go,

Regards,

J.

[seatkid]

I bow to your collective opinions but may I humbly point out.....

 

On all the TIS wiring diagrams I have checked, there is no "F38" switch, all switches have the designation Nxxx. F38 would be a fuse, and there is no F38 in models 1998 through 2003. Prior to 1998, F38 was the fuse for the Seat control units (seat heaters)

 

Its quite clear on the TIS circuit diagrams that N289, near the fog lamp, controls the booster heater in all variants/ configurations.

 

Never known TIS wiring info to be incorrect....(my TIS only covers upto 2003)

 

I can hear it now.....there goes SK again......rant, rant, rant.... :P

[dave_m]

I too have checked TIS wiring and it definately shows N289 being connected to the Booster Heater Control. (N289 is the one near the foglamp)

 

However, this does not affect the booster heater but the one on the wiper linkage which i cannot seem to find on the TIS wiring diagrams definately does.

 

I have confirmed this using Vag Com measuring blocks, whilst shorting out the two sensors.

 

Therefore I can only assume that the wiring diagram on my version of TIS must be incorrect or refer to a different model. :P

[seatkid]

OK I accept that... :P

[dave_m]

it would be nice to get hold of a "correct" wiring diagram as if this is bit is wrong what else may be??

[Jeff115]

Apologies for misleading you seatkid, 'F38' is a VW/SEAT naming convention for the ambient temperature switch taken from both Additional Heater and Heating and A/C Workshop manuals. TIS obviously has a different naming

 

However Additional Heater manual says and depicts that this switch controls auxiliary / booster heater operation wrt ambient temp and Heating and A/C manual says that it switches off the a/c clutch at temp < 1degrees.

 

Regards,

J.

[Jeff115]

Sorry to quote my own post but a thought just occurred :P

The ambient temperature switch (F38) located on the wiper linkage and behind the battery:

1. switches on booster heater to heat coolant at temperature less than 10 degrees plus

2. switches off a/c magnetic coupling (clutch) at low ambient temperatures

 

I previously thought that the temp. sensor at the fog lamp controlled the a/c but there you go,

Regards,

J.

- if one bypasses the ambient temperature sensor using a resistor as suggested on another post, then what effect will this have on your a/c i.e. will this stop your a/c working?

 

Regards,

J.

[Guest adekeys]

Circled in the picture. It simply unclips from the arm.

 

Also in the picture to the right is the connector that is plugged into the back of it with a 10A mini-fuse in it!

 

http://www.bigtrucker.co.uk/images/heaterswitch.jpg

What does the 10A fuse do?

[marinabrid]

any thing will do to cross the pins, i used a bit of wire last yeaer but then i thought if out went wrong the mini fuse will blow and no further damage to wiring.

i on 2nd year now with terminals bridged.

a/c works fine everything ok when water hot enough booster heater turns off on its own

[Masked Marauder]

Circled in the picture. It simply unclips from the arm.

 

Also in the picture to the right is the connector that is plugged into the back of it with a 10A mini-fuse in it!

 

http://www.bigtrucker.co.uk/images/heaterswitch.jpg

What does the 10A fuse do?

The fuse means the booster heater will always work regardless of the outside temperature. It then cuts out once the coolant is warmed up.

 

I put it there as I found that during the winter if there was any prolonged idling with he heating on full then the engine could not sustain the heating, but as the sensor is in the engine compartment with the hot engine the booster did not work!

[Guest adekeys]

Just got in from a quick mod, thanks guys as within 5 mins it was all toasty :o :o

[Jeff115]

The fuse means the booster heater will always work regardless of the outside temperature. It then cuts out once the coolant is warmed up.

 

I put it there as I found that during the winter if there was any prolonged idling with he heating on full then the engine could not sustain the heating, but as the sensor is in the engine compartment with the hot engine the booster did not work!

Beg to repeat...

 

If, as the SEAT workshop manuals suggest, that the ambient temperature sensor which is clipped to the wiper arm in the plenum chamber both controls operation of the booster heater AND protects the a/c by stopping the operation/engagement of the a/c clutch at temperatures < 1 degree,

 

then if you bypass the ambient temperature sensor by using a resistor or a mini-fuse

 

will your a/c attempt to work at low temperatures thus potentially damaging it?

 

MM and adekeys - does your a/c still work at < 1 degree ambient temp?

 

Hope not,

regards,

J.

[Guest adekeys]

got a split in one of the a/c hoses but cant get to it without a car lift. I guess if you dissable the a/c in cold weather with a fuse removal then add the fuse to the plug to keep you warm. you wont use both at the same time then

[Masked Marauder]

I don't understand what you are on about Jeff?

 

If the switch does as you say and stops the air-con working if the switch is closed (below 4 or 10 degrees) then having the fuse in the connector would disable the air-con.

 

So why was my air-con working all through the summer? The fuse was in then too.

 

In any case my wiring diagram shows that the switch is only connected on the air-con on the V6 petrol engine. All other references to the switch are either for the booster or independent heating (a more advanced version of the booster heater) on diesels.

 

On the V6 it is part number 1H0 959 625 and it is between the thermal switch on the engine and compressor electro-magnetic clutch. The switch type is normally closed and allows power to flow through it unless the temperature is below 4 degrees when it opens and breaks the circuit.

 

On diesel engined models with the additional heater the switch (part number 701 959 625) is between either the clock or the alternator and the heater, and is open preventing current flowing through it unless the temperature is below 10 degrees, when it closes and completes the circuit to the booster heater telling it to start.

 

So to surmise, 2 different engines, two different switches, two different functions.

[Guest adekeys]

Is this a mod on the newer models?