I just got my AC working again (with new compressor, dryer, expansion valve, AC thermostat). After returning from the shop, I notice that the cooling fan is always running, even at start up early in the morning. I also notice that the temp gage rise steadily after 20 minutes of normal freeway driving (no up hills). It heats up an extra 30% from average. As soon as AC is turned off, I can see that the temp gauge drops down to where it's suppose to be. Are these two problems related or what can I check to diagnosis the issue?
It sounds like they are related. Check the wiring from the sending unit to the relay and then the cooling fans. It sounds like there could be an electrical issue there that is showing a false reading to the gauge and keeping the fan on. NOTE: You may want to have the coolant temp checked to make sure how hot it is getting. They make a tool that can check it without opening the radiator. Remember, never open the radiator when the engine is hot.