Sounds like the thermostat is sluggish to react to temperature changes
The temperature gauge on a car fluctuates because the car's thermostat is opening and closing. The gauge goes up when the thermostat closes and the gauge goes down when the thermostat opens.
Thermostat probably needs to be replaced.
1990 Chevrolet Lumina temperature sender is located on the back side of the thermostat housing. The sender has a wire that goes to the temperature gauge.
Your car is starting to overheat or your thermostat is going out. Get it checked.
Check/replace the thermostat.
A malfunctioning thermostat can cause your temperature gauge to go up and then allow the gauge to go all the way down. When the thermostat is stuck closed, your engine will overheat and water will not get to your heater core. When the thermostat opens the engine cools down and water flows to the heater core.
if the temperature goes up on ur gauge but it is not overheating means ur thermostat is no good
Could be low on coolant (leak somewhere) or the thermostat is faulty.
It is normal for a temperature gauge to go up a little bit until the thermostat opens up and the cooling fan comes on. As long as it is not going out of the normal temperature range it is fine.
The thermostat is probably set for 190 degrees and that is the point it opens at.
Either your coolant level is low, or you need a new thermostat because it is stickig, intermittently
Sounds like it could be a bad thermostat - not closing to allow engine to heat to normal operating temperature