Hi guys,

I'm new here and have posted a few questions already and have gotten really great help from the other forum members. Just wanted to say thanks before I forget.

On to yet another question. I've fixed the temp gauge now, and the needle seems to hover just a little under the 220 mark on the gauge while the car is idling hot. I cant take it out and drive it right now b/c its salty and snowy out, and I don't feel like spending hours cleaning it in the cold. I let it run for about 20-25 minutes in the driveway and that seems to be where the needle stays.

However, the fan never comes on. My car is an 85 LB9 with a single fan. The previous owner had the coolant temp switch replaced recently. I have put 12V directly to the fan and it runs. I also have 12V at the hot wire on the relay and my ground is good as well. It seems like no matter how hot it gets, I never get 12 volts at the relay coil to activate the fan. What gives? Does the fan just not usually come on in December in Chicago? How hot should the car run on the gauge and at what temperature is the factory fan supposed to come on?

Thanks,

 

my guess would be a fuse and/or the relay.

 

i had a similar problem, the power wire running to the fan was cut . the other thing is the fans usually didnt come on in my car till like 215- 225 i believe that the fan should come on stock at like 210.dont believe the stock guage cuz they suck my stock gauge was like 30 -35 degrees off and they are known for that on of the mechanics i know said so you really can only get a round about temp with the stock gauge. you might also have a bad fan switch or you can get a lower temp switch for the the fans to come on.

 

Thanks for the help guys. I just checked the 10A fan fuse--its good. If I'm interpreting the diagram properly, there should be 12V always at the brown wire to the relay coil, correct? When the CT sensor signals the ECM that the temp is 220, the ECM takes 12V away from the grn/wht wire on the relay coil and opens up a ground path, energizing the relay and turning on the fan. If this is the case, I never get 12V at either leg on the coil which would mean the fault is somewhere in the wiring...

Am I on the right path?

 

i'd say your on the right path if your fans arent coming on on my 87 there is a fuse in the line up by the switch near the radiator try lookin up there because i found out that that fuse runs alot of stuff

 

OK, I replaced the relay and the fan comes on in diagnostic mode no problem. Still will not come on with car running. Now since the roads are salty/nasty, I am not driving the car. I have been experimenting by letting it run long periods of time in the driveway to get to operating temp. Gauge needle gets to around 210 and then hovers, not getting any higher. Ambient temp is 30-32 degrees. The fan does not come on. Who can tell me the preset temp for the fan on an 85 LB9? Also, the fan will not run when the A/C is switched on. The A/C system is low on R12--the clutch will not engage. Is the fan supposed to still come on even if A/C system pressure is low?

Thanks,

 

its a pressure switch so technially no, if its not charged it wont make the fan come on most likely.

keep working with that diagram u seem to be slowing get to the problem. not sure on standard on temp for the fan but most likely around 220

 

did you ever change the fan switch, because i saw how yhou said the previous owner did but did you... he may have put the wrong on in the vehicleor lied to you.. another thing to do is read the haynes manual they are great for trouble shotting