would this be a thermostat?

No heat could be a number of things. I would check the cheaper things to fix first. As already stated, check your coolant level in your resevour bottle to make sure it has enough, but if adding, don't overfill it, it gets hot and needs room to expand. Make sure it's a 50/50% mix, don't just add water because too much percentage of water can freeze and that could lead to a cracked engine block. If you determine you do need to add coolant, check your hoses for leaks, as this could be the cause, and if your coolant system is leaking it's cheaper to replace a hose than the radiator. You didn't mention if you had noticed green fluid on the ground. I think your year of vehicle takes the green colored fluid not the red but you might want to ask about that before adding fluid, if you cannot see any of the fluid in your system. Another cheap fix would be to check your fuses to make sure one hasn't blown, disabling something. Just pull one at a time and check to see if the wire is solid or broken, replace with correct amp if needed, do not use larger amp fuse because it could allow too much current to a device and cause it to burn out. You can usually find the fuse box under the steering wheel dash, but in some vehicles they are located under the hood. The next fix I would attempt would be to change the thermostat and gasket. It's usually less than a $10 dollar part. If you cannot do this yourself or have a friend or relative to do this you will be charged labor at a garage. It is usually cheaper to go to a local garage than to your cars dealer, and this type of repair is fairly straight forward that any mechanic can do. If your heater core has gone bad you will get no heat also. If it's leaking you might notice "smoke/mist" coming from the inside vents and you might smell the sweet odor of the antifreeze, and also possibly thick smoke from your tailpipe, but you did not mention this symptom. This mist is NOT good to breath, so roll down your windows to let in fresh air. Good luck in your repairs, and I'm curious as to what the fix will turn out to be, let us know okay?

~Hank H.

First of all, is the temperature on the temp gauge reading normal? If so, then it's not the thermostat. To find out if the thermostat is working, run the Lumina for about 10 mins. Feel the upper radiator hose to see if it is getting warm/hot. If so, then I would rule out thermostat. With it running, and heater on hot, feel the heater hoses...in a safe area.. Both should be hot or at least very warm, indicating that coolant is circulating...ruling out plugged heater core. Another thing to check...is the heater control valve working? This controls the amount of coolant to pass through to regulate temperature.This is either vacuum operated or cable. Perhaps its not opening up to allow coolant to pass through.

After reading everybody above, each one has a part of the solution. And everyone is right.

1st fill the radiator with water and pressure test the system for leaks. You can do this by running it but a gage would be better.

Check the radiator cap. These can cause the pressure to drop.

After running it full of water, if you get heat, you know your were low in fluid.

If this test worked, add a can of flush to it and drive for a few miles.

If it is the original thermostat and cap, replace it after a good flushing.

Fill with the correct antifreeze and you are done.

Look for a Haynes or similar type manual for you car. It spells out these simple operations in detail

First of all, your location doesn't matter...your car's engine has to run at around 200 deg. whether you live in Alaska or Florida. The thermostat controls minimum engine temperature so if the temp gauge in your car is not coming up to the normal level within 5 minutes of running, then the 'stat needs to be replaced. If it is at the right temperature than things to check are coolant level, fan operation, heater core flow and blend door operation. Remember, heater cores can be clogged internally and not have an external leak. This can cause no heat.

With a 1998 auto, the thermostat has seen better days. That would be the 1st item to change. Your mechanic will want to do a cooling system power flush to remove the crud inside the system...It maybe a good idea.

Before you take it to the mechanic check your antifreeze/coolant level. Heaters don't work good when antifreeze level is too low. Might rule that out first before paying someone. Oh BE SURE TO USE CORRECT TYPE ANTIFREEZE.

try the thermostat first because that is the cheapest and it is the most likely problem then try your heater core

if the temp gauge is reading the right temp it is not the thermostat

if it was the thermostat, your cars engine would run really cold because it would be stuck open. i doubt its your thermostat. take it to a mechanic, its probobly your heater core.

boy - o boy stormy this is definitely a guy thing and by all of the above answers your getting lots of real good ideas and solutions, good luck.. i know i can't stand it when my car acts up.

its not the heater core unless its leaking make sure there enougt warter in the car thats the comom problem