Water temp guages can be off. A friend's gauge is off about 14 degrees, reads hi. Get guage accuracy checked. Running a/c with R134 will add 10- 15 degrees to your water temp at idle. R12 won't but not many systems using R12 anymore (except mine). 220 okay, 240 shouldn't happen unless there is a problem, like electric fans not kicking in, etc. If mine went to 240 I would shut it down. JMO.