Sorry for the late reply. Using R134. Interestingly, this winter, such as it was, I thought my WP was on its way out as well. With the heat on, and at idle the air was lukewarm. Once I got under way the heat was at normal temp. Then the weather got warm again and didn't need the heat. Also, the car was not getting up to temp so I replaced the thermostat which appeared to be stuck open. New one works great as the car gets to normal temp and stays there.