Pontiac Repair: 94 pontiac grand prix 3.1, reek havoc, 2 cooling fans

Question
approx 1 month ago, the battery died in the car, but the instrument panel and door locks went wacky before all electrics died.  Hubby replaced the battery all was well but the low coolant light kept flashing, coolant levels fine. To be safe, hubby replaced the thermostat, water pump, serp belt, all levels fine.  The car's temp gauge always showed the car just under 210, but after hubby replaced everything, it was over 210, and if having to idle at any loc for extended period of time, it would go to the next mark btwn 210 and 260, but the fans would kick in and it would eventually cool.  After the low coolant light kept coming on after a week and hubby saying not to worry about, i'd had enough and took her to the mechanic who discovered the 2 cooling fans werent working properly, they unplugged the sensor and both fans kicked on, so they determined sensor needed to be replaced.  It's since been replaced but now a ck engine light has come on, and I'm waiting for the call back from the mechanic, any ideas as to what could be going on?

Answer
Hi shiela:

the electrical issues you had a month ago are more then lilley not related to the issue you have now. Those 3.1 engines were noted for head gasket issue and intake manifold gaskets leaking. the low coolant light comming on even know the system was full was due to the low coolant probe/module in the radiator going bad. I think when the thermostat was replaced there was an air pocket induced into the cooling system. there is a proceedure needed to purge the air out of the system any air in the cooling system is not a good thing it will reek havoc on the cooling system. the new thermostat wil not work right if there is an air pocket in the ssystem. If you continue to drive it with air in the ststeh mand it continues to over heat your going to have head gasket fialure or worse. unplugging the coolant sensor makes the engine computer think there is a fault in the system and it will turn the cooling fan on as a fail safe to a potential overheat. if the sensor was replaced with a faulty one or a cheap aftremarket one that can cause the fans to not work and then inturn cause an over heat. with out seeing it I can't tell you for sure what the issue is but I think that this issue was induced when the thermostat was replaced and the system not bled properly. Just guessing I can't tell you for sure what the chain of events here were but from what you told me I think that is what happened.... good luck :)