cooling fan coming on high for no reason on 2011 cruze.

[Street Fighter]

I know this is not a chevy cruze sight. but I am in need of help.I have a 2011 chevy cruze that my daughter use to get back and to college. the car is not running hot but the fan comes on at any time it choses and it sometimes starts low and it soon goes to high and stopes the ac from working so it can put all the air to the radiator.I have changed all sensors that are related to the cooling system. I have changed the thermostat also.some times it comes on as soon as the car is started and sometimes it wait about three or four minutes. I have taken the car to the dealer and they don't seem to know no more than I do about this. do anyone out there have a cruze and have run into this problem?

[pajeff02]

Hmmmm. Did you swap out the fan relay? Hook up a scanner and see what the ECU thinks it is seeing as far as coolant temp?

[Street Fighter]

Hmmmm. Did you swap out the fan relay? Hook up a scanner and see what the ECU thinks it is seeing as far as coolant temp?

I took the car and had it put on a scanner and this is what it said. POOB7 engine coolant flow low/ performance.In other words the coolant flow was weak which I believed was causing the engine not to heat up fast enough causing the fans to come on.I removed the thermostat just to see if there would be water flowing faster though the engine.I do know that this can also cause the engins to over heat also because the water will sometimes move so fast it will not cool the coolant. after doing this the same fan issue happened again, there is no way to bleed the air out of the engine, I was told you have to work all of the hoses hoping you have all the air out of the system if not over heating might happen.I did that and started the car and the fan came on about 1minute after I started the engine.I shut the hood pissed off and went in the house got up the next day drove it and it did the same thing, after about 30minutes of driving the fan had gone to working like it should.I heard the water pump making a noise from time to time, but how did the air get into the system before I replaced the thermostat and do you feel that the air was my problem? The water pump was changed about two years ago but I started hearing the noise about two months ago.there is no leaking from the pump just a little noise sometime, I plan on running the car about a week on the highway and around town and see just what it does than I plan to change the pump and pray I can get all the air out of the system again. Thanks.

[pajeff02]

Air in the system is bad. To purge air, with the engine cold put the front end in the air on jackstands open the radiator cap and start squeezing hoses. This this will help any air pockets work their way to the radiator. Let the car set in this position for a bit and then repeat this process. If the coolant level in the radiator drops as air is worked out make sure to top it off (just leave enough room so you can still squeeze the hoses). Again, with the cap off, start the engine, turn the heater on to max, and let the engine warm up. Keep feeling the upper hose as it should start to warm up slowly and then get hot as the thermostat opens. Keep squeezing hoses and once you have a little temp in the engine you can blip the throttle as well. Unfortunately, the stock temp gauge is a POS at best so do not rely on it for an accurate reading (our car runs around 185 degrees... the gauge reads 205). A laser temp gun or scanner should be utilized to determine actual coolant temp. If the upper hose stays cold, you either have a stuck thermostat or an airlock.

If you suspect the water pump is bad, with the engine cold, loosen the belt tensioner and then spin the water pump pulley by hand. Also, try to rock the pulley back and forth. Any play means that the bearing is going out, as does a grinding noise or resistance to being spun by hand. Unfortunately, new parts do not always equate to good parts, so it is possible that the pump is an issue.