Car A/C Fusible Plug
If adequate cooling of the condenser is not provided or the cooling load becomes excessive a fusible plug will release the excessive pressure to reduce the possibility of a burst pipe. The fusible plug contains metal which has a melting point of approximately 100–110°C. Fusible plugs or ‘melt bolts’ are used generally on older models or as fail safe measures on new ones.
The main safety device for high pressure control is the high pressure switch.