Heater blowing cold air

[michaelf]

Hi,

I have been reading up on this over the weekend and just ran tests on INPA. Basically, I have no hot air coming out of my vents, although the sensors seems to be working and the flaps do too.

I’m assuming that this leaves the heater valve and heater core as remaining issues? Is there a way to test the core before replacing it?

Thanks

[Bmwe5320023.0]

You can test the core by simply feeling the hoses that go to it under the hood, by the firewall, with your hands. Warm coolant should coming in, and warm coolant should come out. If the "out" hose is not warm, it means the core is blocked and coolant doesn't circulate.

[michaelf]

Thanks. I will run the car up to temp and check this shortly.

Should also have added that the issue wasn’t happening on the RHS vent originally (this was blowing out a little bit of warm air), just the LHS and rear was cold. It is now all cold.

[michaelf]

Just took it for a drive.

Looking from the front of the engine, there are the three pipes running through the firewall. Only the middle pipe is hot. The left and right ones are not hot to touch (warm - assuming from radiant engine heat).

Does this narrow it down to the core?

[michaelf]

Or could it still be the control valve? I’m not sure on the directions the valve is meant to be working

[X5chemist]

Sounds like the control valve. Can INPA cycle it on?

[Clavurion]

On the linked schematic line Nr.5 coming from engine to water valves. Nr.6+7 from water valves to both sides of heater core. Nr.8 common return line.

The water valves are open in rest state so unless they are jammed closed there should be constant warm flow to heater core (slightly colder return flow depending how much of the heat is tranferred to cabin air) if you for test purposes unplug the electrical connetor on water valves. Depending on IHKA temp setting and core temperature sensor reading the water valves are closed with PWM voltage (by IHKA).

https://www.realoem.com/bmw/enUS/sho...diagId=64_1116