Strange Electric Fan & Headlight Problem
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Junior Member
Joined: Dec 1999
Posts: 3
Likes: 0
From: Sanford, FL USA
Strange Electric Fan & Headlight Problem
I'm having a really strange problem here and was hoping that somebody on here could give me some suggestions...
I had been having what I thought was a classic thermostat related overheating problem. You know the deal.. runs warm in stop and go traffic, but cool as a cucumber on the highway. Had the thermostat replaced, and it seemed the problem had gone away. Drove it a bunch that day... no temperature problems.
However, that night it was running warm again. Eventually I thought to pop the hood and check to see if the electric cooling fan was coming on.. and low and behold it wasn't.
However, when I checked it out again in the morning, it WAS coming on... just when it was supposed to. Hmm... I began to wonder if maybe it had something to do with having the headlights on.
So I did a little test... drove the car around with headlights off, ran it hot enough to trigger the fan to come on. Parked the car, popped the hood, verified that the fan was spinning, then turned the headlights on.
The fan stopped spinning almost immediately.
What could be causing this? I'm really at a loss with this one...
HELP!
------------------
Ryan Loker
---------------------
1987 2.8L
Sport Coupe
I had been having what I thought was a classic thermostat related overheating problem. You know the deal.. runs warm in stop and go traffic, but cool as a cucumber on the highway. Had the thermostat replaced, and it seemed the problem had gone away. Drove it a bunch that day... no temperature problems.
However, that night it was running warm again. Eventually I thought to pop the hood and check to see if the electric cooling fan was coming on.. and low and behold it wasn't.
However, when I checked it out again in the morning, it WAS coming on... just when it was supposed to. Hmm... I began to wonder if maybe it had something to do with having the headlights on.
So I did a little test... drove the car around with headlights off, ran it hot enough to trigger the fan to come on. Parked the car, popped the hood, verified that the fan was spinning, then turned the headlights on.
The fan stopped spinning almost immediately.
What could be causing this? I'm really at a loss with this one...
HELP!
------------------
Ryan Loker
---------------------
1987 2.8L
Sport Coupe
Supreme Member
Joined: Jul 1999
Posts: 1,335
Likes: 2
From: Tucson, AZ, USA
Car: '92 Z28; Dk Teal; Her Pkg
Engine: 305
Transmission: Richmond 6 Spd
Axle/Gears: Moser 9", Detroit Locker, 3.70
The coolant fan is powered from a fusible link connected to the junction block near the battery. That power goes to the fan relay (drivers side fire wall) red wire. The blk/red wire goes to the fan motor. The tan/wht wire gets ign power from the 20 ampere FP fan fuse, and the green/wht wire is grounded by either the ECM or the coolant fan switch (above 243 F). If you ground the green/wht wire with the ign switch in the on position, the relay should click & the fan should come on. You may want to check the black wire from the fan motor - it goes to chassis ground. If it is grounded with a head light ground & the connection to the chassis is loose or coroded, the problem you describe would happen.
Tim
Tim
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