I have an 87 tin top I just purchased. First Sami. The temp gauge does not work. While tracing down the problem, I took the wire off tAngry he temp. sensor and grounded it. The gauge worked. When it got about half way up on the scale, an electric motor running sound starts up around radiator area. I could not see anything turning or running, but it kind of felt like air was moving. This was done with the engine not running. As far as I know, all is stock under the hood, except a weber carb, and a lot of smog stuff removed. The fan freewheels when engine is off. Can someone explain to me what the motor running sound is? Possibly electric clutch to engage fan? Thanks

Does the vehicle have a/c?  It's not unusual for a/c equipped vehicles to be fitted with a condenser fan - look in front of the radiator.

On a stock Samurai, the fan will be either "fixed" (no fan clutch) or viscous coupled (both types were used, depending on which market the vehicle was built for - as far as I know, there were no electric clutch fans, and even if it was an electric clutch, with the engine off, the fan would not turn.

That would be it. In front of the radiator there is the condenser fan. Is it normal for this to come on as the temp. gauge rises. I am assuming it would, but would like an opinion from someone who knows. Thanks in advance.

I cannot be 100% certain, but I don't think it is normal - they are not usually linked to the gauge.

On most a/c equipped vehicles I've worked on, the a/c controller will sense an overheat condition and disable the a/c compressor, if the a/c is on, leaving the condenser fan running, or if the a/c is off, it will turn the fan on.  On vehicles of your Samurai's vintage, the a/c controller would normally it's own temperature sensor, and would not be linked to the dashboard gauge.

A couple of examples - an 89 Sidekick, if equipped with a/c would have had THREE temperature sensors, one for the gauge, a second for the ECU, and a third for the a/c controller - on a 98 Grand Vitara, two sensors are used, one for the gauge, and the second one is for the ECU - the ECU then controls the a/c compressor & condenser fan.

Go to Ack's FAQ (www.acksfaq.com) and search for a/c, you should find a link to the A/C installation guide for a 92 Samurai (the a/c systems were dealer installed), in that manual you will see that system has it's own water temperature switch, and please note it is a switch - so on/off only, not capable of driving a gauge.

By the way, there's a lot of other good stuff for new Samurai owners at Ack's FAQ - like factory service manuals.

I used the AC wiring to run the AC booster fan in my 93 Tracker for cooling (after V6 motor swap).  My fan would work when motor got above temp, if the AC switch was in ON, and the fan was also ON (at least low).  So if your fan is sometimes coming on when motor is at higher temps, it may be that both AC and Fan are selected ON.
Also the AC booster fan is only sized to provide additional cooling to AC coils.  While it can function as main cooling fan, when even stock motors are under load without much speed or hot days, it may not provide enough cooling for the motor.