live in a country where the heater is never used. its always the ac cooling that is used. my query is " is there a real benefit if i disabled the heating system by preventing the hot coolant from entering the heater core using a bypass line? what i mean is i wont allow the coolant to flow through the heater core inside the cabin by using a u-tube to by pass the heater core completely.
i will put the bypasstube accross the inlet and outlet hoses as it goes through the firewall. looks easy enough to do but will there be a benefit? will the ac cool better since the heater core completely does not have any hot water flowing thorugh it?
i was hoping this setup will lessen the heat load on the ac system.

 

I assume your question is, if the hot water from the engine does not come into the heating core will the ac cool better.
My understanding is that the hot water gets to the heating core and stays, it does not run through it. And as it is an open circuit (meaning the water does not flow) there is very little heat transfer.
So in my opinion, no benefit from doing the U tube and by pass, actually it might make it worse if you put the u tube inside the car as the hot water would be a closed circuit and would be flowing and would have minimal but some heat exchange inside the cabin

 

Most cars have a heater bypass valve that prevent hot water from reaching the heater core when the heater is turned off. There is an article on PelicanParts (http://www.pelicanparts.com/techarti...ATER-Flush.htm) implying that the author believes this to be the case too since he mentions the standard procedure item of turning the heater on when prepping the car for coolant replacement (search the page for heater core)to allow the coolant to drain from the heater lines.

However, looking over 997 parts diagrams I cannot find such a switch. I find mention of it on earlier Porsches and even on the 991, but tracing the flow I do not see a switch on the 997s. The closest thing is the "collector" shown as item 7 in the attached diagram, but it appears to be more of a splitter than a switch, I see no place where a control input would attach. FYI, the lines shown at the top are the lines going to and from the heater core, exiting the "collector" at the place where clip 9 is sitting.

However, I did find some descriptions of the foam-sealed servo-actuated heater door that makes it seem clear that only the most trivial amounts of heat could get past the door if the heat is not on.

Personally, I do not think this would be worth tampering with. It also leaves you with the old emergency backup in case your car starts overheating, especially in stop and go traffic or during a small coolant leak: You can turn the heater on full blast, roll down the windows, and get a surprising amount of extra engine cooling this way. Not pleasant, but better than overheating. I've had two times over the decades when this has paid off (it was something my dad taught me a very long time ago).