So after replacing my stuck open thermostat at the weekend it appears the new one i put is now stuck shut!!!! Car overheated today, bottom radiator hose (one coming from thermosat housing) stone cold. I suppose that will teach me for not testing it first. My question is about the diagnostic display that you can bring up on the air con unit. I was monitoring channel 51, Engine coolant temperature. This started at ambient and steeadily rose to 90 degrees as you would expect. The instrument display lagged behind but caught up and levelled out at 90 for a good 20 mins of normal driving. Then the instrunment display started to rise until the high temp alarm came on. The air con display did not budge from 90 degrees which i found rather strange. Pretty sure the water pump is ok as can see water returning to the expansion tank and if i put my blowers on max it holds teh temp down a little bit. I guess I'm replacing the thermostat again tomorrow (after throughly testng the second new one). Does anyone know about the air con diagnoses readings and why they will not go above 90 degrees. I thought that this would monitor the temp sensor that feeds the instrument display.