Pelican Technical Article: 911 Cooling Boost

911 Cooling Boost

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Figure 1

Figure 2

Beginning with the 1984 Carrera, to provide additional engine cooling, Porsche added a complex control unit for the heater blower located in the engine bay. When the engine oil temperature is high, and the car is stopped, the control unit switches on the heater blower to get some extra cooling by blowing air through the heat exchangers. Because the heater valves are open, this hot air is simply vented into the atmosphere.

If you have a 911 with manual heater controls and the heater blower in the engine bay, you can make an easy modification to obtain this additional engine cooling. Start by pulling up the rubber handbrake/heater control lever assembly boot, so you can access the blower switch, which is mounted on this assembly. (Figure 1) Using needle-nose pliers or a similar tool (a small hemostat works well), bend the tip of the copper switch contact (right side is easiest to access) toward the front of the car slightly. (Figure 2) Turn the ignition switch on, and operate the heater control lever to see at what point the blower activates. The objective is to have the blower come on when the heater control lever is raised only slightly (3-5mm), so that the blower is activated without moving the heater valve. If necessary, adjust the degree of bend in the contact. Put the boot back in place, and you are done

This small modification will allow you to switch the heater blower on manually when you are stuck in stopped traffic or need a little bit more engine cooling. Best of all, it is free!