Ac panel

[Adorian]

Hello,

Whats the difference between the climate panel which has the max button and the one which has the rest button ?

Please need help i need to change mine.


Thanks

[tmv]

Old and new.
With the "Rest" button, you can warm yourself in the winter /cold day with the engine off using the heat from the engine, while in the car waiting.
There might be other differences too, but this is what I remember for now.

[spadge]

The MAX button has the same functionality of the REST button if the car is turned off.

[Qsilver7]

BMW models that have the IHKA w/MAX button:

...this feature operates at ambient temps between 41°F-up...and if the ambient temp is above 61°F...the fresh air flaps close and the fan speed goes to the maximum velocity. As others mentioned...it also still has the original REST (residual heat feature) that can be initiated when ambient temps are BELOW 59° F.

BMW models that have the IHKA w/REST button:

...this feature allows you to use the accumulated heat on cool/cold days to keep the interior cabin warm while running errands or if stopped at a railway crossing (you can turn the engine off).

REST-residual heat feature explained

[Adorian]

Thanks for this information, but i have one more question if i have thr panel with max can i install the panel with rest just plug and play or i need to code ?

[Qsilver7]

Since the IHKA w/MAX button has a higher level software...I'm not sure if there will be an issue or not if you install an IHKA w/REST button. For certain, your HVAC system will not have the MAX programming. It also probably came from an e39 if it has the REST button since the MAX feature appeared mid production on the e38 & e39 (like around 2000/2001).

As far as the other programs...more than likely there will be some retro-software functions...at least 80%-90% if not 100%.

The e38's, e39's, & e46's HVAC system also received a solar sensor upgrade around the same time that the MAX button appeared...I'm not sure how the e53 was designed...I can't recall seeing the solar sensor in any documentation for the e53's HVAC system.

{e39 IHKA's solar sensor}




{how the solar sensor functions}

[80stech]

My "rest" button works as a "max A/C" as well, maybe it had updated firmware in the past though. Yes, I was just complaining to someone that the E-53 didn't have a sun sensor, sure could use one. The whole IHKA works really well except for not having the sun sensor to compensate.

[Tomdownunder]

When changing the climate control panel it is best to match with a panel with the same buttons. Also the software versions vary. I recently changed mine with one from an E39. Both had max buttons but the replacement one had a completely different part number and the buttons initially didn't work correctly. I uploaded the software from the original unit and then copied it to the replacement unit with PAsoft and the replacement panel works perfectly now.