[Magallon0820]

So here I am again lol. My 535xi, started doing this thing where when I turn heater on, the engine fan goes into like extremely high mode, soon as I turn heater off, it goes back to normal, again this is engine fan not the heater or ac blower, doesn't do it while ac is one only the heater. Please help its super annoying lol.

[ChiltiCoatl89]

There is an older Thread on this issue. When was the last time your WP and Thermostat had been changed? It can also be electrical, i am looking up more info.

[ChiltiCoatl89]

Coolant temp sensor, and coolant level are also things to keep in Mind.

[Surly73]

I would highly suspect the water pump as being on the way out. Read the threads, including mine, with odd fan behaviour. Turning on the heat altered the behaviour because the coolant pump is called for when the heat is required. Generally this behaviour goes away once the engine is fully warmed up because the coolant pump is needed all the time whether the heat is on or not.

Now, pet peeve coming through here, people are not nearly specific enough when they talk about the "heat". Turning on the "heater" also turns on the air conditioning depending on how things are set and coded. If your fan goes to max with the AIR CONDITIONING on, then you might have an overcharge situation or something going on with the AC loop.

So, heat and NO AC? The time it doesn't do it is when the internal HVAC is completely off (e.g. the panel is black - no lights)?

You can rule out coolant temp sensor and some other issues by using the cluster hidden menu to show temperatures all the time. If you start the car cold and it says the coolant is 300F, for instance, you've found your problem.

My water pump went out at 13 years of age around 120,000km with no codes. Until the ECU started shutting it off while I was driving because it thought it was blocked. I had erratic high fan behaviour, especially when the heater was on, and my coolant temp was jumping all over the place, generally too low, except for when it shut down the pump, then I got a stage 1 overheat. All fixed by pump and stat.

[ChiltiCoatl89]

Originally Posted by Surly73

I would highly suspect the water pump as being on the way out. Read the threads, including mine, with odd fan behaviour. Turning on the heat altered the behaviour because the coolant pump is called for when the heat is required. Generally this behaviour goes away once the engine is fully warmed up because the coolant pump is needed all the time whether the heat is on or not.

Now, pet peeve coming through here, people are not nearly specific enough when they talk about the "heat". Turning on the "heater" also turns on the air conditioning depending on how things are set and coded. If your fan goes to max with the AIR CONDITIONING on, then you might have an overcharge situation or something going on with the AC loop.

So, heat and NO AC? The time it doesn't do it is when the internal HVAC is completely off (e.g. the panel is black - no lights)?

You can rule out coolant temp sensor and some other issues by using the cluster hidden menu to show temperatures all the time. If you start the car cold and it says the coolant is 300F, for instance, you've found your problem.

My water pump went out at 13 years of age around 120,000km with no codes. Until the ECU started shutting it off while I was driving because it thought it was blocked. I had erratic high fan behaviour, especially when the heater was on, and my coolant temp was jumping all over the place, generally too low, except for when it shut down the pump, then I got a stage 1 overheat. All fixed by pump and stat.

Your experience with our Cars is awesome, I am taking notes and when I am not when i am on here? lol.