overheat mystery

[MSN]

I had a case recently where the bearings were fine, no seizing, all electricals fine, all relays fine, thermostat fine, water pump fine, thermoswitch brand new, etc. It turns out that the fan motor has a dead spot! The fan will work normally for a while, but eventually, it will stop in the dead spot and will not restart the next time it has power (and will never start again unless I give it a nudge past the dead zone). This makes for an interesting picture of me stopping by the side of the road, jumping out, opening the hood, looking at dead fan, giving it a nudge, quickly pulling my hand out of the way, slamming down the hood and jumping back in the car.
 
I installed a switch on the dashboard that supplies 12V to the coil of the 3rd stage relay (hurricane mode). So, if the fan is currently running, I can actuate the switch and make sure the fan continues to run until I get home. I'm waiting for a good price on a new fan motor ($285 seems a bit rich for my blood).
 
HTH,
Paul Meyers
88 Pearl 5KCSTQ
87 Pear 5KCSTQA



-----Original Message-----
From: Eric_R_Kissell at whirlpool.com
Sent: Thu, 30 Jun 2005 8:14:26 -400
To: c dyer; quattro at audifans.com
Subject: Re: overheat mystery


I would first verify the cooling fan is working.Does the fan blade turn freely by hand? Is there any looseness if you tryto move the blade tips in and out from the radiator? If so, the bearingsare shot and you need to replace the bearings. They are available fromabout any (industrial) bearing supply house, though I do not have the sizeat my fingertips right now.If the fan turns and the bearings do not allow the blade to wobble, startthe car and let it run at an idle until the fan cycles. Watch the tempgauge as you do this and stop things before the temperature gets tohead-warping level if the fan fails to cycle.Note, if the radiator fan has seized or does not turn freely you are atrisk of a wiring meltdown or even a fire unless you have added a fusiblelink to the fan circuit. If you have added previously a fusible link to thecircuit, see if it has blown and then figure out why.Also, the fan should always run when the air conditioning is running, i.e.when the climate control is set on Auto or Bi-Level. Is this working inyour car?HTH,Eric_______________________________________________quattro mailing listquattro at audifans.comhttp://www.audifans.com/mailman/listinfo/quattro