Poor Heating

[RackedE30]

I’m at a dead end on my 325ix. I have been trying to make the heat work better all winter and I’m out of ideas. It blows room temp air at anything below 3k rpm. If I’m on the highway (above 3k) it blows warm air but not necessarily hot air.

So far these are the things I’ve checked and tried. New radiator, new thermostat, new water pump, all new coolant hoses, new heater core valve, and new heater core. I have bled the system numerous different times. I don’t know what else there is to replace. I assumed it wasn’t an electrical issue because it will blow warm air at higher rpm. Any help would be great, I have also noticed the top hose on the drivers side of the engine bay going to the heater core does not seem to get very hot like the bottom hose does.


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[roguetoaster]

Maybe the blend door is screwed up and setting it to max hot does not close off the appropriate side.

If possible I'd also check the heater core temperature and compare it to the radiator/hose to the heater core temperature. If you have some sort of issue along the route you'd know where it is, and if all the temps remain consistent you know you have an issue with the HVAC box.

[cscracker]

Make sure the heater core hoses aren't reversed. If they're backwards, you'll have very little heat and a hot engine. First hand experience on this. The long one with the T going to the reservoir and front of the engine goes on top, short one to the back of the block goes on the bottom.

https://www.r3vlimited.com/board/showthread.php?t=203038

[Das Delfin]

the heater control valve is electronic and can seize shut. Take a look under the dash on the drivers side of the hvac unit and try to find the heater control valve and see if it's leaking or anything

https://www.r3vlimited.com/board/showthread.php?t=98782