Gregory Bender

Heater/coolant circulation pump

DIY and how-to articles on repairing the Saab 9-5 SE.


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Out of the blue my radiator cooling fans would continue to run on low speed for long periods (hours) after the car was shut off. I knew something was amiss because this wasn't happening a few days prior and the ambient temperatures remained fairly constant.

Pressing Auto + Off on the control panel inside the car generated two fault codes: 18 and 19. Code 18 is for the bypass valve solenoid while code 19 is for the heater/coolant circulation pump. I had recently verified the operation of the bypass valve solenoid and I couldn't see how this could cause my radiator fans to continue running. Nonetheless, I decided to remove the circulation pump and have a look.

I found the circulation pump to be non-functional and slowly leaking coolant into the pump and onto the ground (another small annoyance that has been bugging me for a long time now). Also, when I tested the pump operation, I found a direct short at the terminal connections on the pump. That is, the connections on the pump body were essentially joined to one another by corrosion. Good grief, that can't be good.

A new pump is ~$200 from eEuroparts. But, I didn't think I really needed one. We live in a warm climate with only occasional trips to cold country. Plus, it is my understanding that the circulation pump only operates when the ignition is turned off. Apparently, it circulates warm coolant through the heater core so that the cabin gets warmer more quickly. Certainly a feature I could live without.

So, I left the pump out of the car and joined the two radiator hoses with the 34 inch hose connector I picked up from my local auto parts store.

With the car back together I had no more leaks, no more ACC fault codes, and - best of all - no more radiator fans running on low for hours on end.