What's causing my car to overheat?

I have a 93 Honda Accord and earlier today when I was at the drive through my cars temperature gauge started raising slowly. I had already ordered and was stuck in there so I couldn't just pull over and pop the hood, so I turned it off for about 3 min with heater on and when I turned it back on the temperature was normal again. My question is if it's a fan problem or some sort of leak as when I was driving around town it seemed fine until I got to the drive through. And I checked the reservoir and its full, I had replaced the upper radiator hose 3 weeks ago and had no problems at all until today. Any help would be appreciated, thanks!

My first car was a 1993 Accord and it did that too, except on the highway. I turned off the A/C and cranked up the heat and it cooled off. The radiator can get plugged up so the coolant doesn't circulate. They either replaced my radiator or flushed out the buildup; I can't remember. That was years ago.

When it got hot in the drive thru, did you remember hearing the cooling fan come on? That pesky electric fan is usually the issue and caused by a bad relay or thermostat housing fan switch sensor.

It's a $20 dollar part - 1990-1994 Honda Accord Cooling Fan Switch - Beck Arnley 201-1514

Hi so lets start with the basics here a car coolant system is pressurised so water or coolant does not boil till it reaches 122 degrees C. As it is working above normal sea level conditions. So a leak in this system means it leaks away coolant. The man cause is usually the spring in the radiator cap becomes weak over time and needs to be replaced. Then we have the more serious issues of radiator leaking. And engine block due to blown head gaskets. So start at the cheap option a new radiator Cap.