Bad Radiator Cap?

[blkcivic93]

the other day i was driving to downtown to pay a bill with A/C blaring cuz it was hot as hell. when i reached my destination i noticed the temp gauge was close to H, i cut the car off immediately and checked under the hood. the radiator was steaming and i saw some antifreeze on the top of the fan. the reservoir was empty. i turned the ignition on without starting the engine, the fan was running and the temp dropped fairly quickly. i drove the car like a minute and the temp shot back up to H, so i pulled over, walked to the nearest gas station and got some 50/50 anitfreeze (no water needed). the radiator seemed empty when i took the cap off. drop the anitfreeze in, let the engine run, temp held fine so i drove away.

now, yesterday same conditions, hot day, A/C running, engine ran hot but the temp gauge flucuated from mid to high heat. managed to get it back to my apartment. popped the hood and radiator was steaming from the cap and some antifreeze was splilled on top of the fan again.

so my question is is the radiator cap bad, thermostat need changing or what? doesnt seem like a leak in the hoses. somebody please give me some suggestions or answers so my car can run smooth again

BTW, the car is a 93 honda civic lx