I measured the current between the input and the resistor and it was slightly above 1.5v.
Current is measured in Amps A. "1.5v" would be a voltage measurement.
I replaced the resistor for a 1k resistor and everything works well now. I thought that a higher resistor would limit the current much more than a lower resistor, but i probably didn't take into consideration the "direction" of the current. Thankfully it's been solved.
I hate to say it, but there is so much wrong with this statement that it would pretty much take a course in basic electronics to correct.
But, let me say this: The datasheet, for the SN74HC08N states a worst case current demand on any one if this IC's inputs, as 1µA. At that level of input current, the difference between 10k and 1k is miniscule. It should work just fine with a 10k pulldown resistor [you're sure it's an SN74HC08N, and not, perhaps an SN74H08N?]. Which brings me back to that 100Ω resistor in series with the LED on the output. If this truly is a SN74HC08N, then 100Ω really is too low. It should be more like 680Ω to 1k.
The fact that it's "working" is probably a fluke. In fact, come to think of it...if you are shorting across the resistor to achieve a "low" on an input of the SN74HC08N, then you are shorting out the Arduino supply, so, of course the LED goes out, thus mimicking an AND behavior. There are no sparks, or smoke, as one might expect from a short, because the Arduino's voltage regulator has output short-circuit protection.
The proper way to do it is to remove the wire, that is connected to +5V, when you want an input to be low. When the wire is connected, that is a high. When you remove the +5V wire, the resistor pulls the input low [thus the moniker "pulldown"] .
On further thought, because that 100Ω + LED, on the output exceeds the specified ABSOLUTE MAXIMUM current on an output, odd things may be happening -- like a greater current demand on the input, thus giving the impression that a 1k works better than a 10k.