If it is not overheating then the temp gage or the sending unit are bad.
Idle the engine, remove the temp sensor wire on the engine and ground it. If the gauge does not move one can assume it has failed.
Your 1994 Honda Civic will overheat when the thermostat is malfunctioning. The overheated engine can experience the idle to surge. The engine should be turned off immediately.
Low Coolant or faulty gauge
Normal engine operating temperature is 190-215 degrees F.
My Altima had that problem and it was the water pump going out. It started with temperature gauge was moving, but then it started leaking and finally the heater stopped being warm at idle.
No............... Just let the engine get to its operating temperature and service it out at an idle only......
In cold weather, you'll notice that the engine temperature gauge registers only slightly or not at all, particularly if you're driving at highway speeds. You'll also notice that the temperature of your passenger compartment heater isn't nearly as warm as usual. Your car will show a temperature if you allow it to idle for several minutes. The heat flowing into the passenger compartment will be warm as usual. If your thermostat is open, the engine will rarely warm to a level you're used to seeing on the temperature gauge.
The idle control valve works by regulating the idle speed of the engine. The idle speed of the engine is usually controlled by the engine of the computer.
because the air conditioner puts a load on the engine... check your cooling fan relays.. the fan should run with the air on at idle
Engine oil pressure will vary depending on if the vehicle is in an idle state or not. However, on average, it should be around 40, which is typically half of the gauge.
Car engine temp's increase at idle primarily because there is little or no air flowing through the radiator coils to cool the engine coolant. This is partly because the car is not moving, and partly because the cooling fan usually will not activate until a certain temperature is reached.
The engine idle may be set to low to compensate for the AC compressor starting up. Rev the engine a few times to see if it stops. If it doesn't, there may be a problem with the AC temperature signal or motor mount.