Jeez that HVAC system is fun isn't it? Any help gratefully received...

I have pulled the heater box, pulled out all flaps and sanded down/ greased shafts except the distribution flap, replaced the box and a RH blend motor (which had stripped a couple gears, first tried replacing those gears with a new spare blend motor I had, but it still wouldn't move the flap - even though it worked last year on a 9v motor and works when removed from the box but plugged into the HVAC. I think the pot has had it).

Testing the blend doors etc has been weird. To test I connected the instrument cluster and HVAC control unit, then the battery, but not the solar sensor or cabin temp sensor.

Firstly on start up the book symbol was gone; on a later start it came back. My Nanocom claimed it could not communicate with the HVAC ECU when checking inputs or clearing codes. However, sometimes it would work (despite saying each time it would not) and sometimes it just showed blank spaces for values or didn't show or clear codes. This might be because the immobiliser is deactivated in the BeCM. I found a Blackbox Solutions page on the HVAC, it said to disconnect the front white connector at the under seat fuse box if the Nanocam has no comms with HVAC and immobiliser deactivated in the BeCM. I'm not game to try that as I can't see that anyone else has tried that on the net...I don't want to stuff up the BeCM.

First up values for LH and RH blend motors were going in opposite directions -- well, the brand new Valeo RH motor I spliced in (yes double-checked wiring) was going the wrong way, it seems. Values going down when more heat requested, instead of up with more heat, down with cold requested. After the engine had warmed up, it seemed to be blowing hot air except out of the large LH side duct from the box even when temp was set to 'LO'.

Then I left it for a while, went back, plugged in the Nanocom and went to clear codes (as the book symbol had come up). Nanocom variously showed current faults, a RH pot fault, a cabin sensor fault (it wasn't plugged in) and a solar sensor fault (also not plugged in). The RH blend door was slightly sticking when I checked its operation when I swapped the motors. Even though it worked perfectly smoothly just before I put the box back in the car...

Yet the RH motor values seemed to right themselves, going up for heat, down for cold. The temps out of the box corresponded correctly.

So now I don't know what to do. Only think I can think of is connect the solar sensor and cabin temp sensor and test again. Possibly try disconnecting the front white connector at the fuse box. Should I try sticking a screw between the heater box halves to free up what might be a sticking RH blend door? Should I just burn the thing?

I'm leaving it alone for today. Although with a few disruptions and side jobs like gluing broken plastic, HVAC pixel repair etc, I have spent a week on this. It's getting a bit old now, but I'm thinking that I should try to fix this problem while the dash it still out.

Oh, and where's the bet spot to slice the RH vertical duct? Just above the securing screw tang half way along its length or up near the T-junction? There's no way it's going back in one piece without disturbing my freshly installed, not leaking (yet) o-rings...

EDIT: Just connected the temp and solar sensors and retested. No book, no fault codes, all working as it should... I'll give it another go in the morning and if all clear I'll put it all back together.