[dave dale]

Hi Geoff,
For what it might be worth, here is my contribution: When I first got my 403 in the late nineties, there was hardly any heat available in the cabin. I had the heat exchanger radiators in the footwells backflushed and all the pipework, valves etc. cleaned or replaced. Although there was much better heating, I was still a little disappointed. After everything was checked again I posted the question on the BOC forum. I was advised by someone who had been through the same problem to always leave a window slightly open. Result – a huge improvement! I was also reminded by the adviser that the Drivers' Manual states that a window ( rear quarterlight is recommended if I remember correctly ) be left slightly ajar. I was reminded again of something that I already knew but had forgotten – " when all else fails then read the instructions "! Anyway, it is so hot in the cabin now that I often drive in the dead of winter, as is my preference, with the driver's window fully open
( except when my girlfriend is a passenger, of course ). Another interesting little discovery is that, for some strange reason, leaving the nearside front window slightly open directs cold air to the driver only, without impinging on the passenger, and vice versa. It also demists the screen rapidly. As a consequence, when I have my girlfriend in the passenger seat in winter, she cooks gently in the cabin heat whilst I drive in shirtsleeves with cold air keeping me comfortably cool from the slightly open nearside window. I also fashioned some quick – release radiator blinds from clear perspex which clip onto the outside of the radiator grilles. Makes warming up quicker and maintains a higher coolant temperature. A few years ago I drove the 403 to the former East Germany in the dead of winter. Temperatures were consistently well below zero but the cabin stayed as warm as toast, which leads me to suggest that there would be no need for you to replace the original heating equipment.
Good luck. Dave Dale.