My center vent temperature was only 7 degrees so I popped in another can of gas, one with system cleaner, seal conditioner, leak sealer and oil in as well as 8oz of gas. The result was a center vent temperature of 3.4 degrees with an outside temperature of 24 degrees in the shade. Now that's a result..... Here is the chart, 'A' is center vent temperature after running the engine at 1500RPM with the aircon at fully cold for 10 mins. 'B' is the outside shade temperature. The clear area in the curves is where the vent temperature should be.