Ok, I just bought my 2008 a few days ago. Seller advertised the AC as working perfectly, and it was, for about 5 minutes during the test drive around the block. On the way home I noticed the AC stopped blowing cold after I came to a stop. Got on the interstate and it started working again about 30 minutes later.

Figured it just needed to be recharged but that ended up not being the issue. The problem has persisted for a few days (I travel for work) and I finally decided to pop the hood and do some troubleshooting. This is when I became worried.

I had just finished driving an hour with no AC yet again, the car was definitely warmed up. Let it idle for about 10 minutes while I watched the fans but the radiator fan (driver side) NEVER turned on. If I turn on the AC both the radiator fan and condenser fan will kick on, but otherwise nothing! Should I try replacing the lower temp sensor or should I be looking for a fuse/relay problem? Any help is appreciated as I love the car but I'm about to sell it if I can't figure out this issue.

Tldr- AC stops working and never works again until car is completely cold, radiator fan wont turn on unless AC is on. Not getting a temp warning on the cluster either.

 

Unless someone messed up (modified the) wiring, both fans should turn on simultaneously (they are wired in parallel).
Make sure bot fans have good grounds! if so unplug the suspected fan and connect directly to 9 volt power (9 volt battery or a battery for 9 volt cordless tool) source. If it does not work replace the fan.

 

They both turn on but only if I turn on the AC. Otherwise, I don't see either move after getting the car to temp and letting it idle with AC off. It was 93 degrees outside today when I tested. Drove the car for an hour, put it in neutral in my driveway and watched for 10 minutes. Never had either kick on.

 

So let's clarify:
You are concerned that fans are not turning on when the engine temperature is getting elevated (possible overheating)
On my car the fans are turned on after driving 200 feet at 10 mph (first gear) in the parking lot while getting to my carport.
The fans are turning on when ECT reads 98 degrees C (used to be 96) You need to borrow scanner with life data to read this temperature. If fans are still off at 100 degrees C I suggest taking out the thermostat and check. Idling without load is not producing lot of heat; the car either needs to go uphill or revved up in park/neutral at 3000 rpm. Poor circulation (stuck thermostat) will cause return radiator hose to be significantly colder than upper one.