heya guys, recently my car has been playing up in respect to the heater cold/hot and also my temp guage goes up and down . this happens randomly,when the cars warm ,one minute the heater will work,then after a while it blows cold even though cars been running for 30 mins. also the temp guage fluctuates between halfway and top of gauge and before its never done this. started happening 3 days ago. i am thinking its the thermostat as this is surely the only thing connecting these two problems ?