So, My 2002 Cavalier Z-24 has an overheating issue. I know the cooling fan is dead, but as long as the car is moving it keeps itself cool, only causing issues if I sit and Idle for long periods of time. I have the replacement fan, and will be changing that out real soon. My problem is that the car temp gauge has been in the red a lot lately. I put coolant in and normally this fixes the issue for a month or so, but recently it has only fixed the issue for a day or so max. I don't want to keep adding fluid for fear of over pressuring the system, I have a new thermostat but it is a royal PITA to change with my limited access to the right place to do the work. Is there anything else anyone could think of to fix this issue other then changing the thermostat and the cooling fan. I have a slightly above average amount of knowledge on repairing the car, but other then those issues I can not think of what could be wrong. I recently thought about the water pump, but I had one go out on an '82 s-15 and the Cavalier is not acting at all like the water pump is bad. The heat works above average, so I know the thermostat closes, I am wondering if it is staying closed and this is causing the overheating issue. Any advice would be super helpful

I recently went thru a lot of issues with overheating and mine boiled down to the t-stat. I had replaced it with an aftermarket one and it kept giving me issues. I finally up an oem one(acdelco) in it and that fixed my issue.