The stock guage goes up gradually to about the 220 mark on the guage and then the fan comes on. The guage drops back to about the 160 mark ( I'm guessing the mark between 100 and 220 is 160) and then stays around there. Yesterday it went up all the way to high the end gradually then dropped back to about the 160 mark and then stayed there. Engine did not get that hot. It did this with the old thermostat and does the same with the new lifetime thermostat I put in. temperature hardly ever goes above the 160 mark with a/c on. Could this be a bad guage or sender or is something slse possibly going on?

 

Sounds like the fan is not coming on just right. The gauge going to 220 is normal, fan comes on at about that temp. Fan will run constant with AC on so the temp will stay on thermostat temp. The temp going way up over 220 is a problem though. The secondary fan (if you have two fans) should have come on at about 235 at least.

 

Help me to understand this, the fan should stay on when the A/C comes on? So, if the fan is not on while the A/C is on, then there's probably wrong with the fan or control of the fan?

 

Depends on the setup on this car. Some cars the fan will run full time with the AC on, some cars it will run only when the high side pressure gets to a certain point, fan will cycle off and on. If AC system pressure is low the fan may hardly run in this case. A check for primary fan circuit is to shunt the A and B (top right) terminals in the diagnostic connector under the dash by steering column, then turn on the ignition switch, this will set a relay test and the fan should come on.

 

That's a pretty good tip, I had no idea I could do something like that, unfortunately I'm at the point where I have the fan out and am attempting to check it.

Another member posted that you could remove the fan, suspend it so it turns freely, remove the (+)terminal from the batter and connect a wire from the battery to the fan, and then run a wire from the (-) terminal to the other side of the connector on the fan. This should make the fan run if the motor is good. Correct?

If this is true for a 90 Rs Conv, then my motor is bad. One side note, when I was removing the fan, the motor of the fan became trapped by the tensioner pulley, while trying to get it loose, a wire connected to a relay looking part mounted just behind the headlights between the battery and the radiator (which had a straight connection from the batter then has about two other termials that are connected to wires that collect into one of those corregated wire containers and goes somewhere (it may be the + feed for the fan) because when contact was made between the motor fan and the tensioner pulley, the wire just fried and went poof. haha It was kinda mesmerizing, I just stared at it for a few seconds before I realized what was happening then I removed the fan quickly and it stopped, but not before it totally fried that wire.

Now I have to replace that wire. It connects to that terminal looking thing I mentioned, but inline is a small cylindrical piece of black plastic that surrounds the wire. What is that? can I just splice and replace the part of the wire that fried.

Thanks for yer input. 'preciate it.

 

Sounds like you fried a fusible link, designed to burn out instead of burning the car up. Not sure if you can replace this section or not? Might call a couple parts stores and get info. Probably need some kind of big fuse or something in there at least.

 

I had enough wire left pre-cylinder looking thing to reattach some extra wire. i tried to match the guage, and it seems to be working fine. I still have no idea what that part is, it connects about 4-5 different wires onto one screw in the middle of this relay looking thing that simply divides the wires. Anyway, I replaced the fan motor and the fan works fine. Overheating problem fixed, and the A/C now seems to cool as it should.