Overheating

[ahamay]

hello members

getting stuck into fan related problem.

car: porsche carrera 2 my 2000

problems: the heating circuit reaches 225 degrees, the 2nd fan stage its starting and cooled down to 194 degrees.

I connected the durametric and try to activate fan stage 1 and fan stage 2 and the first one doesnt work despite it states that activation command its sent

from the beggining what are the potential issues

thanks

[Loren]

Both fans or just one?

Try swapping relays to verify the problem.

[ahamay]

both fan s are working but just at 2nd fan stage.

where are the relay's location Loren?

[Loren]

Above the fuses.

[ahamay]

Loren,they are 8 .could you please advice wich one is?

[Loren]

19 RADIATOR FAN 1 STAGE1 141. 951.253.B

20 RADIATOR FAN 1 STAGE 2 141.951.253.B

21 RADIATOR FAN 2 STAGE1 141.951.253.B

22 RADIATOR FAN 2 STAGE 2 141.951.253.B

[ahamay]

here is the panel . porsche my 2000

http://img541.imageshack.us/img541/4121/image014pk.jpg

Edited June 19, 2010 by ahamay

[ahamay]

Loren

the relays panel look kind of different that the schematic you give.maybe because it is an german model.

i have checked all the relays,they work fine.could you please advice where are the water temperature sensors wich send water temperature and activate the fan's.both of them the one for stage 1 and the other for stage 2.thank's

Edited June 19, 2010 by ahamay

[Loren]

Is the problem on one side or both?

If it is one side then you likely have a bad ballast resistor.

[ahamay]

on both no stage 1 either can not activate stage1 with durametric.

[Loren]

If you have the Durametric software and 1 set of fans does not run then there should be fault codes.

[ahamay]

no fault code

via drive links activation i can activate the stage 2 no problem,it state that the drive link is running and they start..when i activate the stage 1 the software states that drive link is running but the fan s not starting.i was assuming that is a relay issue but is not i switched the relays and veryfy them all.

[Loren]

The only difference between low speed and high speed is that there is a ballast resistor in the circuit for low speed.

Still it would seem odd that both would fail at the same time.

[ahamay]

The only difference between low speed and high speed is that there is a ballast resistor in the circuit for low speed.

Still it would seem odd that both would fail at the same time.

yes it is strange that both are not working on low speed.but assuming that resistors are both broken(very few chances both radiators are bought new,with new fan s new housing and new resistors)why they still work on stage 2.those resistors are in charge sending the water temperature to dme?

it could be a dme software error?

[Loren]

I seriously doubt a DME error unless someone has re-programmed the DME.

Is there any sign that someone re-wired the fans. Some people have 'hacked' the fans with a bypass so they always run fast (I personally do not think this a good idea).

[ahamay]

i have not seen any strange wires accros.but if they were re wired as you suggest,it supose that the fan's start at approx 190.

they start at 225.

i don't know exactly how the Porsche system work but i assume that the stage 1 has to start at approx 190 and stage 2 at approx 225.

Loren where is the sensor that send this command,because i don't think that the ballast resistors do that i guess that this sensor it has to be actually in the water to report the accurate temperature.this faulty sensor is the only think i have in mind considering the test's we've done but this is also bizare considering we have no related fault codes.very anoyng

ANY INPUT IS APPRECIATED

thank's for your support

Edited June 20, 2010 by ahamay

[Loren]

"The engine temperature sensor is a double NTC, i.e. there are two resistors in the sensor housing. The plug contact is new.

One temperature resistor (resistance can be measured between contact 2 and 3 in the plug housing) supplies the signal used to display the coolant temperature on the instrument cluster. The other temperature resistor (can be measured' between contact 1 and 4 in the plug housing) informs the DME control unit of the coolant temperature.

The signal from the temperature sensor is used by the control unit

• to calculate the injection signal during the warm-up phase

• to enrich the mixture when the engine is started

• to determine the ignition angle in the warm-up phase

• to control the electric fans.

The engine temperature sensor is located in the coolant duct housing." Item 2 in the diagram below.

[ahamay]

i will check it in the next hours,what i should measure?the resistance?wich is the corect value? do you think it can be his fault?there are no fault codes after all..

let's see it other way..if the DME actually send the command to start the first stage what eles it can be(except the relays)

very strange behaviour

Edited June 20, 2010 by ahamay

[Loren]

This is where a PST2 or PIWIS tester is very handy. With one of those testers you can test each circuit individually to narrow the problem down. You can also view the temperature the sensor is seeing. So rather than trial and error you reduce the number possibilities and narrow the problem down.

If you swapped relays and problem stayed where it was then the relays are fine and the problem is in the other part(s) of the circuit.

[ahamay]

Loren

PST and not to mention PIWIS are the tools but not as much affordable as the durametric.

however,checked the temp sensor is OK

removed the bumper and plastic housings of the wheels,diconected the fan coupling and measure it.

when i send the comand via durametric for stage 1 it measure 12,65v on 1 circuit ,when i send the comand for 2nd stage display 12,65 for the other circuit.there are 3 wires out there per fan.1 brown ground,and 2 yellow each for a fan stage.so there is bassically a fan problem.

what do you advice?

[Loren]

Electric fan, speed 1 (low speed)

Coolant temperature higher than 96.75° C or air conditioning switched on.

Electric fan, speed 2 (high speed)

Coolant temperature > 102° C or air-conditioning fluid pressure switch closed (coolant pressure > 16 bar).

I would try one new ballast resister and see if that fan works.

There is a DIY here

[ahamay]

thank you loren

i will wire them as a bypass for the ballast and see if the stage 1 can be activated

keep up the good work

[ahamay]

also Loren wich setpoints are corrects?

[Loren]

Mine came from the Porsche 996 Carrera Service Manual.

[ahamay]

mine too(my99-01)any ideea where to get the 02-05 manual?