I used 4-port valves in my 940s - both the 945T I still have, and the 945 NA which @VolDan now owns.
There's a reason why I got away from the factory design:
With 700/900 HVAC systems, the heater core is (nearly) always in circuit, even when the temp control is set to cool. Temperature regulation is carried out by the flaps inside the HVAC, not by the flow of coolant through the heater core.
If you hit the recirculate button, it operates that valve. Which cuts off the coolant flow to the heater core.
Why is is this bad - well, the most likely time you'll operate the recirc button is when the air conditioning is on and you want to cool the interior of car down quickly because it's a bloody hot day. Interrupting the engine's coolant flow on said 'bloody hot day' doesn't do it any favours, especially when it's already trying to shed heat without the extra burden of an air conditioning compressor being added to the load.
In Dan's 940 and mine, I used a Commodore 4-port tap, like this one -
When the recirc button is operated in our cars, the coolant flow isn't cut off between the heater core inlet and outlet - and thus isn't cut off from the water pump to the back of the head. Instead, the 4-port tap effectively 'loops back' the coolant flow from the heater core inlet (from water pump) to the heater core outlet (to the rear of the cylinder head) like in the 3rd pic above.
Doing things this way means you're less likely to cook the engine which is working hard enough during a heatwave. Especially if a sweaty passenger operates the recirc button and the first you know of it is when your coolant temp gauge is reading 'meltdown'.
