Not reading temp after new rad/fan wiring question

[Ryan Fudge Rush]

So my rad split at the top a few weeks ago in the seam between the plastic and metal which created a VERY bad leak causing it to spit coolant all over my engine bay, anyways, ive since gotten a new (used) radiator out of an '86 manual swapped sedan at my local pick-a-part. Luckily the radiator was still the auto rad and the old owner only capped off the nozzles for the A/T fluid so ive been running it with no issues other than the temperature gauge not working This is my second rad swap as ive also done it in an auto 89 EX (US LX) which had the same symptoms until i messed with one thing or another and got it to work, only issue is im not sure what i did before on the '89 to get it working.

All three cars mentioned (local donor '86 LX, My '88 LX, And buddies old '89 EX) were carbed and auto, aside from the swapped 86.
Also i want to add that sadly the 89 was sold last month so i cant go look at what i did there, and that my temp gauge in the '88 did work with the bad rad (which is still around) before and after it blew.

Any ideas ? I also don't have a rad fan hooked up right now as it had a broken blade and used to be wired straight to the ignition without the original harness, though i have two spare fans (which im assuming is needed as i still have a/c) with plugs, i still dont have the harness. Would it hurt if i skipped the plugs/harness and wired it directly to the ignition or elsewhere ? I know its ghetto but hell, i don't even have a key to lock the door ! so it doesn't have to be clean, just has to work as it should.

So any ideas with either ? This car only gets turned over for a few minutes every few days (to test as i replaced the starter recently and still had issues with the positive and negative wires from the batt) so im to not stress it too much but it does worry me not having a proper cooling system, while not knowing how well its working either.

[conozo]

If you have FI the temperature guage sending unit is plugged in right next to the thermostat pointing toward the rear of the car.
If you have carb its under the intake manifold pointing toward the rear. Make sure the wire isnt loose. Neither of these parts are near your radiator work. The only other reason it would not read is if you have not bleed the air out of the system correctly.

[POS carb]

If you have FI the temperature guage sending unit is plugged in right next to the thermostat pointing toward the rear of the car.
If you have carb its under the intake manifold pointing toward the rear. Make sure the wire isnt loose. Neither of these parts are near your radiator work. The only other reason it would not read is if you have not bleed the air out of the system correctly.

Agreed. To check the gauge short the signal to ground and turn the key on. If it shoots up to the H then your gauges and wiring are good.