97 GC Fan Runs w/Engine Off , No Key in Ignition...

This is a new one for me...
My wife parked and turned off van after a 30 mile trip yesterday. I noticed a few minutes later the fan (psgr side) was running. Engine off, no key. Turned key to check gauges... temp OK, in middle. A "service engine" light on dash was on, but had been on a few days. Fan seemed to go faster, then slower, repeat. Finally, disconnected the + battery cable and it stopped. Reconnected it this AM, ran engine a little while, then turned it off. Has not reoccurred...

Sticker under hood says fan may come on at any time when ignition is ON... Never had it do this (to my knowledge) with it off though.

Any ideas what this is caused by? ('97 3.8 Gr Carvn ES)

THANKS!

Steve in VA

Radiator fan relay is going bad. Relay is attached to the frame under the air cleaner. Check the connector for heat damage when replacing. It is an electronic relay and it transfers heat to the frame; make sure that area is clean and the relay is tight.

Radiator fan relay is going bad. Relay is attached to the frame under the air cleaner. Check the connector for heat damage when replacing. It is an electronic relay and it transfers heat to the frame; make sure that area is clean and the relay is tight.

THANKS. I actually replaced that about 8 months ago w/ a part from NAPA -- only non-dealer place I could find it. Hmmm. At that time, fan stopped completely and car overheated.

After posting earlier, drove to Lowes and back. Didn't happen. You thinking I'm on borrowed time with relay?

Could be. Keep an eye on your temp gauge. Ck with NAPA to see what kind of warranty you have on the relay.

THANKS jpb53.

Problem solved. Replaced Fan Relay located under the air filter in engine compartment. Brought in the part (AR473SB) and receipt and NAPA replaced it for FREE b/c, as you said, it was still under warranty (bought bad one 9/08). Would not have guessed they'd do that w/ an electrical part! NAPA dude explanation -- got a 1 in a 1000 bad one. Suggested I could extend warranty if need be by NOT bringing in orig receipt if it happens again

Since I've done this twice now, FYI to all who may care, easier way is from the top. Take out entire air filter assbly -- pretty simple. Don't crack rubber vent tube as I did. Takes all of 10 minutes.

THANKS again! This forum and folks like jpd53 have saved me thousands of $$ over the years. Plus helped me teach my kids a little about car repair.

Steve in VA