Diagnose radiator fan (Page 1/1)
John W. Tilford JUN 23, 05:00 PM
Overheating in slow traffic, cools on road. Sure enough, got home and let idle with the front "hood" up. Fan was not moving and did not kick in as the gauge went up to the same reading as the warning light came on earlier. Barely touched fan and it started right off.

Disconnect and reconnect all electrical connectors I can find? If not fixed, how to check out thermostat switch? If OK, recommend good replacement fan?

1988 GT, but with 1995 3.4 and 4T60. Radiator replaced about six years ago. Don't know what coolant degree thermostat is installed.
David Riedle JUN 23, 05:07 PM
Sounds like a defective temperature switch to me.

Does the car have air conditioning? If so, there is an easy way to test the fan...turn the air conditioning on. This should immediately start the fan. If it des not, the fan may be bad.
theogre JUN 23, 05:55 PM
If AC or jump motor fan switch wire to ground doesn't run the Rad Fad...
motor, fan relay or wires to them can be bad.

And/Or

Fan Ground is 1 wire screwed to metal under left HL assem. Is the bigger wire there. (Small wire is HL etc. ground and tied to right HL area.)

Spin HL motor up to get access to the screw.
Clean to bright metal and coat w/ brake or silicon grease.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

[This message has been edited by theogre (edited 06-23-2020).]

olejoedad JUN 24, 09:36 AM
John, your car has a 195° thermostat in it, unless it has been changed since I did your swap.

Turning the A/C control ON should kick on the fan. If it doesn't, and the fan will run when you give it a nudge, your problem could be corroded relay internal contacts, dirty ground, or the fan motor itself.

If it is the fan, this would be a good time to upgrade the fan to a more modern design.

Give me a call if you need anything.
donuteater306 JUN 29, 11:53 AM
Wait, you said that you "touched" the fan and it started working? I would guess it's a bad connection at the harness for the fan motor, or the fan motor itself is bad.
John W. Tilford JUL 05, 05:58 PM
Fan was bad. $40 from NAPA. Fixed.

All much easier to diagnose and replace after a Forum member told me the radiator shroud (to which the motor mounts) is only held in place by the two, easy to get to, hex head screws at the top. Removed screws, pulled up shroud, could easily access two conductor connector. Fan was "open" (infinite resistance on ohm meter). 12 volts available across input connector when A/C selected. NAPA replacement was exact and easy after I remembered the center hex head nut for the fan is counter-threaded = clockwise to remove. Installed new, replaced shroud. Did have to go under and guide the bottom edge of shroud into two steel spring clips. Again, easy.

[This message has been edited by John W. Tilford (edited 07-05-2020).]