Postman87

A couple of week ago i purchased an F which was advertised as head gasket blown. Intention was to use it for spares for my F and TF. Having examined it and done a few tests it appears not to have a blown head gasket. Last week i could hear the fan running when i switched the engine off after running up to operating temperature. This week when trying to get it up to temperature ( to run an engine compression test ) it won't fully reach operating temperature the fan doesn't come on and the coolant is constantly circulating. I'm thinking thermostat issue. Am i missing anything else ?