Can someone tell me if this is the correct sensor/switch that should be installed in the passenger head? I'm asking because I cannot find a direct replacement that has the same terminal as the one that's in there now. I do not know if a previous owner bought the wrong sensor/switch and cut the plug off the harness and crimped a spade connector on.

All the sensors I see have the connector that looks almost like the knock sensor
1991 Z28'350 TPI

 

That looks more the like the sender for the temp gauge, which would/should be on the dr. head.You're correct about the (thermo switch) connector looking like the knock sensor.

 

In the stock configuration, the fan switch is in that location, and yes, it should have the mushroom style connector. The switch in the picture might function perfectly well, it's possible for a replacement switch to have that blade type terminal. When the engine temp exceeds 235* F, that blade should pass ground.

 

Agree w both the other guys: a stock fan switch would have a single pin Weatherpak connector. You're right, it's the exact same one as the knock sensor uses. Looks kind of like a "mushroom", but gotta be careful calling it that, because a stock temp gauge sending unit has an ENTIRELY DIFFERENT connector that's been called a "mushroom" since they started using it in the late 60s.

Whatever that is, it's NOT a stock fan switch. Might be an aftermarket one.

First thing I'd do is check and see if the fan works right. (comes on at the right temp, or possibly, some typical-ish aftermarket temp like 180° or something) Then if not, change it out, and put one in with the correct connector along with the appropriate pigtail.

 

im going to have to get with 1MeanZ, he tweaked the tune , and see what he recommends for a fan switch based off of what he changed in the tune for fan turn on temps. I am running a 170 degree thermostat. I have yet to see the drivers side fan turn on. It's only in the 50s here so the odds of the engine getting up to 220 degrees are tough. I've been letting it run for 15 minutes in the garage and the gauge is at the 12 o'clock position with the passenger fan running while I have the heat on. I know the factory gauges can be inaccurate too.

This is a sunny day April-October car which may see 1000 miles a year. I still need the heat to actually work which is why I didn't go with the 160 thermostat so I'll have to see what 1MeanZ says about his tune and go from there with a new switch. I just want reassurance knowing that I have the corrrect part in that location and not some random sensor/switch that the previous owner tossed in because he thought it would work correctly.

 

Main thing to look for would be, a [mr spock]"sen-sore"[/mr spock] will be a variable resistance with temp. Something on the order of, many 10s of k ohms at very cold (sub-freezing) temps, some hundreds of ohms like 500 - 2000 at room temp, some tens of ohms like 50 - 150 at "overheating" temps. Whereas, a fan switch will be OPEN below its set point, and SHORT above that. not linear, no "in between". It's a SWITCH as opposed to a [mr spock]"sen-sore"[/mr spock].

You can put it in the freezer, boiling salt water in a pressure cooker, etc. to test its properties. Or, just buy one like you want and be done with it.