When one of my two fans (not sure which one) comes on the voltage drops well below 13, almost to the first white mark on the factory gauge. Could it be a bad fan motor or is it a short somewhere? I tried replacing the relay with a good one that i had laying around but it didn't change anything. If it's a short where is a good place to look (around the relays?). Thanks in advance.

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1989 Iroc-Z TPI 350 auto 4-spd Removed MAF screens K & N filters, stock other than that.

 

Check to make sure the fans are both working. If one is moving only slightly then that is a bad fan (duh). Turn on your a/c to check if they're both working at the same rpm. If you had a short a fuse would blow no doubt so I don't think the motor stopped. I know when I had my fan motor go it didn't blow any fuses so I'm not sure really about the voltage drop. If you're at idle and it's dropping below 12 volts then there might be a problem. If both fans are running, try putting the engine at 2400rpm and see if the voltage stays low. If so then you have something wrong.

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, Jon (91 RS too many mods to list), getting new engine in summer

 

Does it drop down and then come back up, or does it stay down below the 13 volts? A momentary drop is normal but it should come back up.

 

It drops to the first white mark on the factory gauge and doesn't come up unless I rev the motor up a little, then when the fan goes back off it comes back up. I disconnected the fans one at a time to see if it was just one of them and found that the passenger side fan was causing it. I'm thinking that I nead a new fan motor. Would a bad fan motor cause the voltage to drop so much? I also think my alternator may be to small.

 

Yes, a bad fan motor can cause this. Is the wiring harness long enough so that you can plug the connector from the suspected bad motor into the known good motor? If so you can rule out whether it is the motor or the wiring.........but I do suspect a bad motor. You also might want to try swapping the two motors if you don't want to invest in a new one without knowing for sure. How many amps is your alternator? Does your car have all the power accessories?

[This message has been edited by TunedPort350 (edited January 15, 2001).]

 

The alternator has 100a on it so i'm guessing it's a 100 amp. I've had it tested for what that's worth, and they say it's good. My car has power everything. I'll try swapping the motors and will probably buy a new one in a couple days just to see if that fixes the prob. Thanks for the help.

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1989 Iroc-Z TPI 350 auto 4-spd Removed MAF screens K & N filters, stock other than that.