So I've been having some weird issues with the automatic HVAC system in my 05 cooper S. The AC works great and the heater used to work great until a couple weeks ago. I ran diagnostics and found no codes. After the heater stopped working, I notice when I slam on the brakes hard, the air coming out of the vents switches to hot air, regardless of whether the temperature was set to a colder or hotter temperature.

This makes me suspect it's the blend door actuator because of how it switches to heat when I hit the brakes hard. Maybe it's loose somehow and can't stay in the heat position? Also, very occasionally, I'll turn the heater on and it works for two seconds, but then goes back to cold air. Am I right in suspecting its the blend door actuator?

 

bump

 

Having a similar issue. What did you use to check for codes?

 

I’ll dig up the code I have it somewhere.

My 2006 r53 has no heat. I think it’s the actuator to the blend door / flap. Says it has a short to ground iirc.

 

Really? It gave you a code? I just used the diagnostics system built into the automatic AC system.

 

Here is my thread

https://www.northamericanmotoring.co...t-working.html

inpa gives a code and calls it the “engine temperature mixing flap” I think.

on the ac control unit I have “FF” “01”. Forgetting what that is now. Need to look it up again.

as far as I can tell the actuator is under the dash on the right side. Might be able to access by removing the glove box, might have to take out the dash, I don’t know yet. Really hope it’s the first

 

I will update when I get more. Please do the same

 

Yup, will do, probably going to call a shop today because it's freezing down here and hopefully have them diagnose the issue.

 

Here's an update: found the issue. The blend door was infact the problem, and it had popped off its hinges because it snagged on a wire for my dashcam, so it wasn't turning like it was supposed to.

 

Found this video while researching a similar problem.

I’m starting to think about making a Sticky thread that people can quickly find useful videos like this to troubleshoot their own A/C problems.

 

I am having the same issue. Have the glove box out. Where is the blend door actuator? I see where the hot-cold dial/switch cable moves the arm in the passenger side footwell..

 

Did you bother taking any PICTURES??

 

Your observation about the air switching to hot when you brake hard is intriguing. It could indeed point to a faulty blend door actuator. Those little parts can cause big headaches! As for the intermittent heating, it's another classic symptom. If you're up for it, tackling the repair yourself could be rewarding. But if you prefer expert hands, consider reaching out to Repair Near Me. They fixed up my AC last summer, and I was back to cool breezes in no time. Best of luck getting to the bottom of the issue!