Been busy this last couple of days. If anyone has a similar fault to me here is how I fixed it.
Symptom:no heat, only cold. This means that the mixer flap or mixer flap motor is faulty if you follow the workshop manual. I got my local independent (AHM Hartley Wintney, very good) to check on diagnostics and it came up with the mixer motor also. So knowing that the only way in was to dismantle the heater and air con box as well as the fan, I got the air con de-gassed.
Now following the steps in the excellent alfa owner 'home made haynes manual' I dismantled all the climate and heater components. This is about a 2 hour job so don't start just before tea if you need the car the next day! This is not a difficult job, just awkward and requires a couple of good socket extensions and angled drives as some of the bolts are difficult to get to. The screw behind the heater hoses that holds the mixer unit to the bulkhead caused me no end of trouble.
Anyway I replaced the heater matrix which was on borrowed time (btw the one for a 164 is a straight swap and cost less than a tenner new!) So cheap to maintain these Alfas!! See`link below https://sslrelay.com/buypartsby.co.u...php?recordID=5
The mixer motor/servo nearly foxed me as it worked if you jiggled it about but fitting it back on the bulkhead caused it to jam in the cold only position. In the end I stripped it out and found that an idle gear spindle was not locating in the casing and this was causing the gearbox to jam. This in turn was caused by a flake of plastic breaking off the outside of the casing. Anyway a good splodge of araldite later all was well and the whole system was working, also no more faulty air con warnings on the screen.
I assembled everything again which took about 2 hours and found that the heater box and the fan unit definately go back easier if you install them simlutaneously, very tight though.
I am off to get the air con re-charged tomorrow to finish the job.
In conclusion, if you are fairly OK with spanners this is not a too bad job but you wouldnt want to do it every day. Whats more without the gas recharge it has cost me less than 20 quid, plus the grazed knuckles! I daren't think how much a main agent would charge!
Many thanks to the suppliers of the original details of this job, I would have struggeld without them.