2 questions on ford windstar 2000

My wife's car had similar symptoms, heat - no heat, engine temps varing toward overheating summer and not in the winter. Turned out car had slow leak under the coolant reservoir. Low coolant level in radiator was causing no heat from heater (no fluid flowing to it) and it caused the crazy gauge reading (running hot in summer and not in the fall-winter). I took the car to shop and had leak repaired and have had no problems since. If you can't spot the leak, a radiator pressure test will rule this out as the cause of your problem. Just hope it's not a cracked head gasket or worse... Good luck, hope your problem gets fixed.

Thank you MrPerk. But it isn't that. I'm sorry I should clarify that the gauges going crazy has nothing to do with the heat. https://www.youtube.com/watch?v=ouno9F3twLA It just does it. I think I figured out that it may be the fem module. Does anyone know for sure? I did put more fluid in my coolant and the front air window vent blew hotter. Not sure if it will stay on. It has only been one day. I have yet to check today. There isn't a leak on the ground. Would the coolant reservoir leak on the ground? Do I need a shop to check the radiator pressure? I do not have any air coming out of the vent in the front. What could cause that issue? I have replaced the blend door. And I hear it clicking now. All suggestions are helpful.