Heater stopped working :(

[TruEdrty]

Ive had it about a month its a 90 325I.

The heat worked fine and then it started to go in and out when it felt like it.
If i left it off it would work once the car warmed up now it doesn't work at all.

Help im freezing!

[TheB1G Lebowski]

Try thermostat first. Ive also read that the cooling fan sensor can be faulty and cause the fan to run all the time lowering the temp across the core of the radiator. Im in the same boat and i too need heat.

[FredK]

When you operate the car, does the temperature gauge go to nearly the middle? If so, it's probably not the engine thermostat.

There is probably an obstruction in a line feeding the heater core, the heater core electric valve is faulty (electrically, or obstructed somehow), or the heater core is plugged.

Feel the bottom hose of the heater core inlet/outlet pipes. These are stacked one on top of each other at the firewall, next to the fusebox. If it is hot, hot coolant is getting to the electric valve, and either the electric valve or core is faulty.

[wodcutr]

There is a small hose that connects to the upper and lower hoses of the heater core by means of a bypass valve. This valve is controlled by a thermostat and is prone to failure ie getting stuck open. When the valve is open the coolant going thru the heater core is reduced enough to not produce very much heat especially at idle. If your car is running at full temp and this hose is warm then the bypass valve is open and needs replacing. Otherwise the core could be clogged, or the electric valve is stuck closed and not allowing any coolant to go through the core.

If you turn your temp knob all the way to the left (cold) you should hear the valve actuate as this is the setting that sends 12v to the valve to close it. If no noise can be heard, then it is faulty and needs replacing. It is a distinct clicking noise. Good luck!

[TruEdrty]

Hot air is still coming through because when the car is warmed up and im driving hot air is blowing as long as i have the temp nob all the way up.


Thank you all for the help

[bimmer_E30]

My old E28 did that, and it was the Air Control valve or somthing like that.

[TruEdrty]

Ok so it just randomly started working again lol I think my car is bipolar

[bmw325csi]

sounds like the resister by the blower motor bud