Coolant sensor-what is it used for?

[dkw_dude]

Hi

Had a slightly disturbing moment yesterday, Was accelerating when I heard a "pop" sound, looked in the rear view mirror and saw a big cloud of smoke Was a few 100m from home so drove back slowly. No smoke anymore but high temp. Opened the bonnet/hood and coolant fluid was spilled in the firewall area. A closer look and I discovered the plastic thingy where the coolant sensor for the electronic climate control is installed was in 2 pieces.

The Q is: Coolant sensor for the ECC-what is it used for? I replaced the plastic thing with a SS pipe without the temperature sensor. Will the ECC demand a minimum temperature before the flap for the heating opens?

Will check if the plastic tube for installing temp sensor is still available tomorrow..

[Rusty]

Post up some pics please, as we didn't get climate in the UK.

[Sleeper_Avant]

it will be used along with external temp, internal temp, temp inside cooling ducts (multiple no doubt) and your broken coolant temp sensor

all used as an average to create that magical, desired number on the climate display inside the car

[BosnianS2]

You should check to make sure that you headgasket is not dead. Reason I am saying this is because i had a same experience with my RS2, while I was accelerating exactly same thing happened, this plastic peace broke and coolant went everywhere, just to find out that the reason was that i had bad headgasket and due to pressure caused by it in coolant system this peace blew apart (probably cause it was old and brittle and at this point weakes part in coolant system). Just my five cents

[johne]

The climate ECU uses that sensor to determine when the engine is warm so as you say it can open the heater flap and turn up the fan speed from slow. However, if that sensor is missing the climate ECU reverts to using a calculation of engine temperature based on engine off time before the last start.

I bought the sensor but never fitted it and my climate works fine so I'm sure yours will too without the sensor. The sensor was fitted to several different Audis in the '90's so there's more secondhand options but the plastic on those may well be just as brittle with age.

It certainly won't do any harm to live without it and just see if your climate performs as usual.

John

[dkw_dude]

Thanks guys! Didn't like the headgasket theory I replaced it with a straight piece of tube, runs with no smoke from the exhaust at idle now. Fingers crossed! Checked the local Audi dealer, plastic part is available and not expensive Must be used in other models also I think. Will get it tomorrow.

[macspring]

You should check to make sure that you headgasket is not dead. Reason I am saying this is because i had a same experience with my RS2, while I was accelerating exactly same thing happened, this plastic peace broke and coolant went everywhere, just to find out that the reason was that i had bad headgasket and due to pressure caused by it in coolant system this peace blew apart (probably cause it was old and brittle and at this point weakes part in coolant system). Just my five cents

dkw was your head gasket ok following the issue with the coolant ?

Just curious, found while surfing through old threads.

Thanks.

[UrS4boy]

Climate Control "T"

The PN for this is 4A0819497. It is used to hold a blue coolant temperature sensor that is used exclusively by the climate control computer. Not related to the G62 engine coolant temp sensor.

More info here: http://forums.quattroworld.com/s4s6/msgs/22679.phtml