95 neon overheating

I have a 95 Dodge Neon. It has had a problem wanting to overheat on hot days (90 degrees ambient and higher) when the A/C is running. Recently on a day it was moderately hot (90), I noticed it wasn't just when the A/C runs, but if the fan is just on you can see the temperature visibly increasing. I thought before that the a/c compressor load was causing it, but just having the fan running will cause the increase in temp. I replaced the radiator cap, it was old and probably needed it. How on earth can the fan cause the engine temp to rise like that? I don't think the slight load on the electrical can do it because the temp doesn't increase any with the headlights on. I'm going to replace the thermostat today but any suggestions will be appreciated.

 

i have a few ideas but i am not saying them with seeing the schematics, if the thermostat doesn't help, a fan switch could be a possibility, also check for leaves and stuff blocking the radiator, i am assuming the cooling fans are working, if enough air isn't getting pass the condensor to the radiator when the a/c is on then the condensor will act like a heater to the radiator, if air flow is restricted