Kappi2907

I understand and noticed that some 964's activate the air duct blower after engine shutdown.
I my case after shutdown the blower never activates, during a spirited drive I can hear the blower (in both speeds), so everything with engine on is ok.

Any suggestions on why my blower is not activated after shutdown?

fasterlaster

I only had it happen for me when the engine was very hot on a long road trip.

Kappi2907

What's very hot?

Position of the needle on your oil temp gauge e.g. 10:00?

Thanks

justin-in-athens

I have noticed that my mint C4 kicks the blower on after shutdown when the temp is just slightly over the 9 o'clock position. ( reg running temp, just over the second bar)

However my driver C2 never seems to operate after shutdown. I am considering that it could be a faulty temp sensor on the heater duct in the engine compartment. There is also a resistor on that duct, but I am unsure of its function exactly.

Kappi2907

Both sensor and resistor in my air duct ate nee.

justin-in-athens

The next thing to look at would be the CCU and the blower motor control unit located in the frunk mounted directly behind the gas tank.

If your CCU is not original to the car, (there were several p/n's produced that look identical) that could be an issue.
I don't don't know how to "test" either component unfortunately.

Kappi2907

Ccu is original. Hammer is reporting no errors. On the ccu connector I can measure the heat sensor signal. The unit in the trunk is unknown to me will check this tomorrow. Thanks for tips!

HalV

With a scantool you can test cycle the fan in low and high speed. I would assume you could do that with a Hammer.

Kappi2907

Yep, both speeds working.

Didn't know scantool has this function.

Where can I find the test function in the Scantool?

HalV

In the ScanTool Window, Select Climate Control and then Click the "Test Output" button. It will iterate through all the tests for the CCU. You'll want to use the "T-OBD User guide.pdf" located in the Tore's Installation zip file to guide you through the tests.

Kappi2907

Thanks.

Do you have the partnr of the blower control unit?

Can't find it in the PET list.

Thanks

HalV

You may want to verify that your rear blower temp sensor is working properly.

Kappi2907

Temp sensor is new and working ok.
Measured the resistance.

Kappi2907

Scantool is not cycling through the climate control tests.

I have '89 C4 964. I suspect the original CCU is not supporting the tests.

All the motronic tests are working correctly.

I'm now suspecting the after market alarm has something to do with the blower not working after shutdown.

Still I didn't figure out the blower control unit in the frunk, I cannot find it....never heard of it. Anyone?

HalV

I've never heard of the Blower Control unit either. I thought the CCU did all the control work so also be interested in learning more. Are you sure you're getting your car up to a temp that the blower will cycle on? Mine rarely comes on.