If you want to disable the heat but not remove it entirely, you could put in a valve on a heater hose so you can shut off coolant flow during the summer. Just in case you want to keep the heat around at the flick of a switch.

What I did with mine was my car has a valve for the heater hose that shuts off coolant flow when the heater controls are put in the strato-vent position. Vacuum switch didn't work anymore so I just ran the vacuum hose from the heater hose valve straight to the intake. Problem solved. If I wanted heat back I just unplugged the vacuum line and put a cap on.