Our 2001 SSEi is overheating, "ac automatically shut off, etc.' warning

Radiator fans still run, little heat if any into pass compartment.

Would this indicate a thermostat replacement?

being that a new thermostat would run you on avg less than $10. If you havent replaced it in a while, I would start there.

Whats the fluid like in the radiator when its cool.... normal level or low. Could be low/out of coolant, or it could be the water pump is out and its just not moving the water thru the block. Either would be a good possibility.

If you could add your year of your car is and what the trim (SE, SSE/SLE, SSEi, etc) is to your Signature, it would be more help in the future. Go to "USER CP", then to edit signature on the left column. You can add more info if you want but its alot of help to know what year range and motor you have. Just something we ask of all new members.

PS: Welcome to the Forum

Thermostats usually fail in the open mode, which means water is circulating to the radiator all the time. They do on occasion fail in the closed mode. It is a relatively inexpensive and easy repair to change a thermostat, so it is usually a good first step to diagnosing the over heating issue.

Read this thread:

https://www.gmforum.com/t277853/

Look for any coolant leaks, particularly around the water pump area.

Start with this and let us know how you make out. If this doesn't fix the issue we can talk you through the next steps.

I am puzzled that the engine is overheating, but you get very little heat in the car. Usually when your engine overheats, if the heat is on high in the car you can roast chickens. What does your temperature gage read? If you open the hood, is the engine giving off more heat than normal? When it overheats, and you shut it off, do you hear a lot of ticking noises coming from the engine (as it cools down)?

Scientific Method!
Tapped on the Thermostat housing lightly, it must have been 'stuck'. Will change thermostat in the daylight tomorrow, I'd hate to have it overheat and freeze this winter. Thanks for your responses and instructions

You my have a air pocket at the thermostat, Other then a clogged cooling system or bad water pump, that'* about the only way to have a over heat.

A lack of water in the cooling system is typically the cause of these symptoms. Being that it'* overheating, it is pretty common for a cooling system to discharge a lot of the coolant when it overheats due to a stuck thermostat. Then when the stat is replaced the coolant is also topped off and that should fix things right up.

Replaced thermostat, old one not corroded, but replaced it anyway.
Did need coolant, topped it off, and now still overheating. No apparent leaks, drips.

Strange thing though, intermittent heat into pass compartment! Sometimes enough to 'roast chickens' and then suddenly no heat at all? Doesn't seem to be related to grade of road or speed (although of course engine temp decreases when drifting down hills.

2001 SSEi

The intermitt heat is normally air moving through the cooling system<cold air> then hot coolant going through <hot air> Prior to the thermostat r/r did you do any work to the cooling system? Did you burp the cooling system enough after replacing the thermostat?What kind of weather is this happening in?
Is there coolant in the oil < oil is milkshake color>or oil in the coolant < mud colored coolant>? Is there coolant in the trans fluid <pinkish trans fluid color>?
Like was said above might be a water pump or maybe a head gasket issue.

The prior work was not done by me, But would this happen suddenly? Northern VA, today high 50s f, no extremes.

I did not 'burp' the cooling system! will start there,

Oil and Trans fluid look normal as well. bbiab