O.K I changed out the fan switch and still no fan unless I turn on the AC. I installed a new relay and the fan started running constantly. I am at a loss. My mechanic thinks the connector for the relay has a short, but i am not sure. Anyone have any ideas? Also does anyone know where I can get the relay connector, or a totally new wiring harness?

 

try and see if the old relay does the same thing and makes the fan run all the time..

it seems like the relay is being grounded and causing the fan to run when the car is on...

 

First what and who's relay did you use? Do this, key on engine off plug the relay in and out from the connector while holding if firmly in you hand. You should feel and hear a click. If it clicks it is being energized. If it does not click it is probably the wrong pinout relay. If it does not click to test remove the heater blower relay mounted near the blower box and substitute it for the fan relay. They are the same. If the relay does click then it is being told to turn on by either the fan sw or the ECM depending on the year and engine. It's not terribly complicated and should not require anything as drastic as what you say to fix it. The connector cannot cause what you describe unless someone rewired the connector incorrectly or on purpose. Keep me posted, we'll solve it. Are you waiting till the engine comes to the fan sw temp? In a single fan application it may be as high as 238 deg. Did the old relay kick on with the AC? If it did the relay is OK and so is the wiring. You did not by chance confuse the guage sender or coolant temp sensor with the fan sw? Give me year, engine and single or dual fan setup and any mods that were done.

 

It's an 89 305. I have replaced both the coolant temp sensor and the gauge sender before. The mechanic is the one who diagnosed the relay. I will be getting the car back tomorrow I think I know more about this cooling fan than he does. Yes the fan did come on when with the AC with the old relay. The mechanic did install another connector for the fan switch because the old one was weathered and it fell apart when removed. Is there any way he could have wired that connector backwards? I will post more info tomorrow after I get the car back.

 

I see what he meant... The plastic inside the connector was melted. I will be going to a junk yard to loof for a new connector tomorrow. The guy said he had a lot of thirdgens, but the none of the wiring harnesses were complete. If I'm lucky I will find one.

 

Are you still referring to the fan relay connector? If so you can buy replacements with pigtails from Pep's, or any auto parts outlet.

 

I replaced the relay connector today and put on a new relay. The fan still only runs with the AC on. I am at a loss. What besides the fan switch could be the problem? The mechanic put on the new fan switch, but I still haven't had time to check it though.

 

I ended uo just grounding the wire for the fan wsitch so the fan will run whenb the ignition is on. I thought the new fan switch was the problem, but I think it's the computer. I will leave it for now. Does anyone know if there are any negative aspects to the fan constantly running? Except, of course the fan motor might go out sooner.