My furnace heats up for about five min then high limit switch trips. Then the flame goes out. What's causing this to happen

Try the blower motor or its control system. Have you changed the air filter.

Changed filter checked blower every thing is clean the flame starts it stays on for a few min then the switch trips

You will need to test the motor control system in the heat mode and also the blower motor itself. There is a wiring diagram on the back of the blower door. You will need a electric meter,tools and the knowledge of how to use them to effect the repair.

Problem: The blower is not removing the heat from the furnace causing the unit to stop working. The overheat/high limit control (safety) is turning off the burner to the furnace to prevent a fire or other problems.

If you have air conditioning on this same system, the indoor coil may be blocked with dirt, causing the same effect as a clogged air filter.