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rear defogger, single heat/dual heat


Vehicle Information: Model: 911T; Year: 1969; Body Type: Targa; Engine (type, size, modifications): 2000T; Total Mileage: 300k;

I am restoring my 1969 911T Targa that I picked up at the factory in May 1969. I am replacing the rear window as the heater wires have failed over the years. The original is a single heat, 100W. I have obtained a new 100/250 watt rear window. The new window has 3 heater sections:(lines, resistance, Watts@12V, Watts @13.8V)a. 7 lines, 1.3 Ohms,110W, 150Wb. 9 lines, 1.0 Ohms,144W, 190Wc. 3 lines, 3.1 Ohms, 46W, 61WMy original factory manual electrical diagram only shows the single heat rear window. The manual says to convert from single to dual heat, change the wiring harness and switch which are not available. My questions are:1. Can I just parallel all three sections (I have a 770 W Alternator) which yields 300W@12V (400W@13.8V)? 1a. That is, will the glass fracture from too much heat? 1b. Is the relay that powers the rear heater rated for 400W? 2. If I should not parallel all sections, which section do you recommend connecting?Tnx, Ken

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