There is a good picture and further info re Johns suggestion in the Garage Shop Manual section of http://www.clarks-garage.com/ it is listed under Heater Malfunctions. These clips are less than a pound from Porsche
However I think that as you are getting heat then your clip is ok but it is one of the three heat sensors that could be malfunctioning. I had this problem and only got heat when the dial was at full or the defrost override button was pressed.
1. The first sensor and easiest to get at is under the bonnet in front of the fresh air inlet grille. This is under the plastic tray right in front of the windscreen and directly in line with the steering wheel (on RHD cars [
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
] ). It is a small black cylindrical probe about 4 cm long. This is the one that failed for me and cost £18 from Porsche.
2. The second one is again behind the glove box at the end of a 40cm rubber tube that leads from that tiny grille above your glovebox. The tube is connected to what 944 Register members affectionately call 'the hairdryer', this is a small fan that sucks air in from the cabin. The sensor is in that fan.
3. The third is at the back of the central twin vent in your dashboard. It is reached (I believe) by removing the instrument cluster and the twin vent. As you can guess I have not done this one [
![Wink ;) ;)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
]
I believe it will be sensor number 1 but if you don't want to risk £18 whereabouts in the country are you as some kind soul may play swapsies with their sensor (that's what I did). It literally takes 5 mins to unplug it and swap.
p.s all advice on here is amateur and liable to blow up your car so don't blame me [
![Big grin :D :D](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
]