[1993NewYorker]

1993 New Yorker Fith Ave w/3.8. Cooling fans don't shut down even after turning car off. They just constantly run. Had to unplug them.

Car had worked fine, then I wanted to check tranny for specs to see what it was doing. I plugged my snap on MT 2500 into it. I had forgot to change the setting and it was for my 1990 Imperial w/3.3. I started the car up and went down the road to check my specs. When I turned the car off both the cooling fans kept running. I thought that was odd. I then checked my snap on MT 2500 and realized I had the wrong setting. So I corrected that. But he fans will not turn off even when the car is shut down and not running. So in order to keep from running down my battery I unplug both fans.

Today I checked the fan relay and it was fine. (I pulled it to keep the fans from continuously running)

Did I fry part of my computer where the cooling fans are controlled?
Or is something else going on? anyone know what else to check? I just find it odd that fans run even with car shut down?

Anyone else here use a MT 2500 scanner with transmission moldule? Any comments or help will be appreciated

 

[Bob Lincoln]

Relay is sticking. It's a common problem. Swap it out with another one underhood of the same PN. I did that and never had the problem again.

 

[1993NewYorker]

Thanks Bob, I'll have to give that a try. I pulled the realay and checked it with an ohm meter. Said it wasn't closed, but haven't put it back in to see if they would still run. Wife took the car to work and should be home soon. So I'll give another relay a try and see what happens.

Thanks for the quick response.

 

[Bob Lincoln]

What happens is that the inductive load of the wiring harness plus the fan windings causes energy to be stored that is released as the contacts open, and it arcs across the contacts, welding them so that the relay stays closed, despite its coil no longer being energized. Sometimes vibration will release them, sometimes the armature springs. Sometimes they stick shut.

A relay such as the A/C relay in a cool climate that hasn't been exercised as much, can often work fine when swapped in.

 

[valiant67]

The relay is the only failure point that will provide power to the fan with the key off.

 

[1993NewYorker]

That's what it was. Just taking it out of it's holder had jarred it enough to free it up. I put it back in and no fans came on, but just to be on the safe side I swapped it out. Wish all my Chrysler problems were that simple. I was afraid I might had messed something up when I had my MT2500 brick plugged in to check tranny specs.

Thanks again Bob and Valiant67