I bled the system and had a ton of air which was expected because I had changed the thermostat, water pipe, and water pump. After the proper bleeding the fan running problem seems to have corrected itself. Today I cycled the ignition and the fan did not turn on like it did yesterday.

I got into the hidden menu by watching a poor video on YouTube, they didn’t do it live time and missed a couple of steps. Either way I made it to menu 7.

I monitored the temp temp on the drive to the inspection station yesterday and it appears good. It slowly worked its way up to 104C but never went above.

Today after letting it sit overnight it was reading spot on ambient (27C). I started it up and idled it up to 62C and shut it off and the fan didn’t run.

I have not looked at a schematic or read any system theory but I find it strange that it is so smart. I mean before I even started the car (just cycled ignition) the fan would run. The only two variables that changed were proper bleeding the coolant system and disengagement of the little tab for the tensioner on the water pump drive. I had the drive in the maintenance position because I was changing the water pump. I read that some of the tensioners have a sensor and turn on or off to in effect turn on or off the water pump while other cars just drive the water pump all of the time. I looked and did not notice a harness or plug on my car. I assume mine is a constantly driven pump system.

I never hooked up the scanner or swapped any of the original sensors back into the car. Additionally, after the bleed I had good warm temps on the proper radiator hoses and tested the heater and also had good heat in the car.

Hope this information help you...or the next guy.

 

Sounds like what my 15 Countrman is doing.
It's 2015 Countryman S, 54,000 miles, the cooling fan began running constantly. The engine can be dead cold over night, as soon as you start the engine the fan is on. As a matter of fact it will start just pushing the start button without actually starting the engine. Once the car is shutdown it will shutdown 6 minutes later. The only code it shows a PO128 code, low coolant temperature, low temperature is not supposed to start the fan, high is. It has no coolant leak, the system is full and I drove it 1000 miles at 70-75 MPH with the A/C on. It runs as normal. It's been in the shop for 3 days and they haven't called to tell me they found the problem. Searched the internet and could not find any mention of a similar problem.

 

Well - I lived with the fan running since the weather turned cold last fall. About 8 weeks ago I brought it in to a really good shop and they poked at it for a few days and finally decided to change the thermostat assembly (which had been replaced a few months before the problem started up again). In fact, they had to go through a couple replacements before they got one they liked. Problem solved.

I had changed the sensor a few times and it never helped. I also traced the sensor wires all the way back to the junction box. The thing that bothered me was that it only happened in cold weather. Car is just fine now.

Jim

 

Car has been in the shop a week trying to determine why the fan runs all the time.

 

bad thermostat or bad ecu

 

Problem was a failing battery causing voltage spikes. The battery was replaced and code cleared.

 

Chevycruizer, you might want to try and use the coolant temp sensor off your old thermostat housing. However, the more I think about it, the sensor in the housing is the one that causes the fan to come on. That's what was happening to me, when I changed my housing. None the less it's worth the swap. You should already have the sensor.