When the car is at idle the temp gauge goes higher and higher when i drive the temp gauge goes back down there is coolant but i have noticed the a/c does not work as well nor the heater in winter 95 z28

If your coolant overflow is bubbling then regardless of what your gauge says you are having overheating issues. If your coolant is missing with no aparent leaks then you need to check your oil for a milky consistency and apearance which would most likely point to a blown head gasket. This would also explain overheating. Hope this helps

Have you checked the coolant level after you did some driving. Often you will get an air lock in the system which will eventually work its way out after you drive a little. As the sender for the temperature gauge is at the top of the engine, it is possible that it is not fully immersed in coolant and hence is giving bad readings. Topping up the coolant will fix that. Some vehicles can be very hard to purge of air and some even have air bleed points located on the top of the engine as it is the only way to get all the air out.

Any chance of a head gasket leak? Is the coolant level still full? These were known for head gasket issues. Coolant is a closed system and level will not drop unless there is a leak. Make sure there is no air in the system. Replace the radiator cap to make sure that it is operating properly.

Have you checked the temp sensor ? It could be faulty or there could be a wiring problem back to the gauge. Low coolant can cause an air pocket inside the system too.

100 degrees is the normal operating temperature for the motor. If it goes higher than that, the thermostate needs to be replaced. The temperature will be higher on the highway because the engine is producing more heat energy due to the higher load on the motor. Diesels idle cooler and the engine will cool down at idle or lower speeds. That is why it is best not to idle your car for long periods of time because this will cause deposits in the engine and glaze the cylinders. The engine is working normal from what you described and there is no reason to worry. I hope this helped.

Coolant sensor may be the problem. It is located near the thermostat housing. It may be sticking between modes & not operating properly.Also make sure coolant is circulating in system.

That vehicle has two coolant temp sensors on it, both are on the passengers side of the end of the head, where the thermostat housing is. One has a two wire plug, this one tells your fans to come on the other is one single pin, this one is for your temp gauge. This sensor works off resistance, the higher the resistance the higher the gauge in the car goes. This sensor has probably grounded out and pegged your gauge in the car. Replace that sensor and you should be good to good, not too expensive either. Good luck.

Try to bleed the system. Also keep an eye on the coolant level. If it drops and you see no leaks the you could have a blown head gasket. Also replace the thermostat and hoses.

check coolant level ,must be low ,chck for coolant loss

you either have a intake leak or head gasket. get a pressure test and then youll find the leak......like i did. $800 later. and start looking for another car......