dfinnegan

My car is running hot in traffic. It got all the way to the 10 o'clock mark heading into NYC last week.

I've read several threads and the p-car DIY Page and have discovered:

1. Jumping relay pins 30 to 87c starts the fan at low speed - indicates ballast resistor is good
2. Jumping relay pins 30 to 87 starts the fan at high speed - indicates ballast resistor is good
3. Removing and testing Temp Sender has results shown below - seems okay (not great)
4. Disconnecting temp sender electrical lead while car is running starts the fan at high speed - indicates the CCU is okay (I think)

Temp Sender resistences:

1. At 60c (140F): 4.0-4.1 K ohm - should be 3.6 - 4.0
2. At 85c (185F): ~1.75 K ohm - should be 1.4 - 1.6
3. At 100c (212F): ~0.97 K ohm - should be 0.9 - 1.0

These resistences seem okay, but a bit off at the low range. The low speed fan should come on at 100c (212F) and the temp sender seems to be within range at this temp.

However, I get no fan even when the temp goes above the low start temp on the gauge. Note that I have not retested after reassembly. Sometimes just pulling things a part and putting them back together helps.

Because the fan comes on when I pull the temp sender connection while the car is running I'm thinking that the CCU is fine.

Is that a fair assumption?

I think I'm going to go ahead and order a new temp sender (~$35), but wanted to run it past you all to see if I am thinking clearly.

Thanks for any and all input.

Cheers,
Dave

H964

leave the car runing until the temp is at 10 . if the fan doesnt kick in, replace the relay with the ac one and see if the fan turns on. if it doesnt, your sensor is bad.
i just replaced mine few weeks back, took me 10min. piece of cake.
good luck

dfinnegan

Mike,

Thanks. I failed to mention that I did swap the relays. That was first.

I'm back from a test drive and found that the fan went on at the low speed temp!

I've ordered a new temp sensor and will replace it when it arrives just as a precautionary measure.

Cheers,
Dave

Dick964

Hello Finnegan (Dave),

Will you keep us posted after you replaced the sensor?
I have the same thing on my 964 C2 Tiptronic.

Car is running great, powerfull and no further problems.
On the highway the temp is good, driving in the city or rural roads the temp climbs higher and higher untill slow speed fan starts...

I'm curious if a new sensor will start the slow speed fan earlier...

thanks,

dick964

dfinnegan

Will do. Note that the link in my first post to the p-car DIY shows the temp settings where things are supposed to open and come on. I had been up to the 10 o'clock mark w/o the fan last week and yesterday the low speed fan kicked in right at 100c (212F) where it is supposed to after I pulled everything apart, tested the thermistor, and put it all back to gether again. I suspect the electrical connection to the temp sensor (thermistor) was less than perfect, but I wasn't completely happy with the test results so I've ordered a new one any way. By the way, it is a really simple diy.

I'll let you know how it all works out after I change the part and drive a bit. Though, it is getting a bit difficult to get up to temperature here in NY as the cooler temps roll in.

Cheers,
Dave

Dick964

OK Dave,

Great !
I'm very curious about the new temp sensor.

dick964

Fred's 964

dfinnegan,
Did you do a diagnostic to see if you had any trouble codes?

dfinnegan

You know, I didn't!

I use my Hammer much more than I ever thought I would and I just didn't think to use it in this instance. I was pretty sure the problem was up front with the blower system and I went straight to the Shop Manuals and began diagnosing.

I'll go put the Hammer on now and see if there are any fault codes.

I'll let you know what I find.

Cheers,
Dave

jimq

Fred bring yours backover to the house this weekend if you want to run the codes again and see if any came back on after the reset we did.

dfinnegan

The Hammer showed three errors in the ECU:

1. Internal Sensor Motor
2. Oil Cooler Blower Temp
3. AC Motor

1. I always get the Internal Sensor Motor error. I'm not sure if this is a false reading, or not.

2. I did run a test with the oil cooler temp sensor disconnected, so this is likely the error beging reported.

3. My A/C is down due to lack of refrigerant and I've tried to run it. The compressor doesn't engage due to low pressure.

This is not to say I didn't mask the "real" errors while diagnosing, but these error codes do make sense in light of what I've done. I'll test again after replacing the Temp Sensor.

Cheers,
Dave

mikecarr

Just picked up this thread!
Are you sure this is not the old failed thermostat problem? Fan sender will not operate because oil remains cool in oil cooler due to lack of circulation. Have you tried checking the lines to the oil cooler - both should be hot when oil temp starts rising!
Mike.

dfinnegan

The fender gets hot, though, I have not put my hands on the lines themselves.

Dick964

Hi Dave,

Did you change your oil temp sensor yet ?

If yes, I'm very curious about the results...


Dick964

dfinnegan

I've received the part, but have not yet installed it. I was to have worked on the Porsche over the weekend, but other things preempted.

At this point I'm afraid the testing will be inconclusive as I have not seen the temp go above the 8 o'clock position for more than a week. It's Fall in NY and the air temperatures are just too low to get the engine up to the fan switch levels.

I continue to notice that the thermostat is opening as evidenced by the drop in gauged temperature readings from the dash. I can see the temperature rise to just a shy below the 8 o'clock position and then dip well down when the thermostat opens and the cold oil from the forward lines mixes in.

I suppose I could let the car idle for a while and see if that will drive it up to the first fan-on temperature level. The last time I tried this the fan came on with the old temerature switch still in place.

I'll keep you posted as best I can.

Cheers,
Dave

Dick964

OK, thanks Dave.

Yep, the daily temperature at this site of the ocean is lower and so is the oil temperature.
Well, we 'll waite...

Greetings,

dick964