HVAC Question/Problem

[Staszek]

Not sure what this could be. So I dont really drive this car at all in the winter. It was 30 degrees today and I drove it around 30 miles round trip to finally get an estimate on my full repaint and my Mtech II kit installed. It was the first time I really used the heat. When I have the heat on my feet I get heat, when I have it on my feet and on my face (middle vents) I get heat on the floor but cold air comes out of the vents even when the car is fully warm.

What could cause that? The heater core is brand new. I would think maybe its something to do with my swap, but if that was wrong would the heat even work on the floor.

[Tzantushka]

Is the temp knob turned to the max temp (i.e. fully on red)?

IIRC when it's half way or partially in the blue and red the HVAC blends the incoming air

[Staszek]

Is the temp knob turned to the max temp (i.e. fully on red)?

IIRC when it's half way or partially in the blue and red the HVAC blends the incoming air

It was turned all the way, but maybe its not set right, I did have the dash out before when I replaced it.

[mjweimer]

It's been a while since I've dug into the HVAC controls so hopefully I am remembering this correctly.....


You likely need to check that the bowden cable attached to the rotary heater knob assembly is still fully attached at each end...one end below the knob and the other at the air distribution box.

This cable runs behind the center panel (below the sliders - towards the passenger side) and ties into the air distribution box with a small tab/clip - Cable #1 in the pic below with the clip #5 and spring #8 at the air dist. box connection.




If the flap does not fully close you will never get heat out of the center vents.



MJ

[Staszek]

It's been a while since I've dug into the HVAC controls so hopefully I am remembering this correctly.....


You likely need to check that the bowden cable attached to the rotary heater knob assembly is still fully attached at each end...one end below the knob and the other at the air distribution box.

This cable runs behind the center panel (below the sliders - towards the passenger side) and ties into the air distribution box with a small tab/clip - Cable #1 in the pic below with the clip #5 and spring #8 at the air dist. box connection.




If the flap does not fully close you will never get heat out of the center vents.



MJ

Good call, I may have not had it connected correctly when I put the dash back in.

[mjweimer]

Definitely. Lots going on with a dash install so easily overlooked...hope it's an easy fix.

[KIRIEIW]

Had a similar issue on my 325iS the other day. Previous owner bypassed the heater core so I replaced it and.. the air coming out the vents still wasn't very hot. After some investigating the issue was the last person who took apart the HVAC panel broke clip #5 in the diagram above (or rather left it out). Without that clip, you'll turn the HVAC knob to adjust the temp but it pulls the entire cable. The cable should not move, it needs to stay in place only pulling the "cable strand" inside the cable for lack of a better word.

I'd say check the cables, make sure they stay stationary and go from there.

[twright]

I have a European E30 without air. No warm air will come out of the center vents. Warm air only comes out the defrost or floor vents.