I have a coleman central air switched over from heat to cool and it blows the E- fuse on the pc board .never had this happen before

Check out the limit switch sounds like its not shutting off .

The switch is not the problem ,it is doing it job.
Locate your vent and put a bend over it because what is happening is on windy days wind will get into vent blowing that combustion air back to furnace causing pressure switch to tripped.

Make sure all vents are open and filters are clean. Likely an air flow issue but possibly, though unlikely, both switches are bad.

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Blower motor is bad or going bad

The AC unit outdoors must be running and rejecting heat by its air flowing through it the 2 copper lines are the refrigerant lines, the fatter one should be "beer can cold" if not its low on refrigerant or not running.

Hello, check the thermostat wiring between the indoor unit and outiside unit and make sure it is secure. Also check the contactor coil on the outside unit and make sure none of the wires are loose and touching metal. You csn also unhook the wires and put them back one at a time and see which one blows the fuse.

Fan control could be on summer switch. or af control not working keeping fun running

It sounds as if your furnace is exceeding the limit tempperature of the manual reset switch. The coleman is designed for the fan to continually run when this limit switch is tripped in order to keep the heat exchanger cool.( it is a safety feature) afew things may be happening.
1. the manual limit switch( the one you have to push) may be defective.
2. The fan may be running at too low of a speed. Turn power off at circuit breaker. locate circuit board on the board there will be one terminal that says heat if the red wire from the blower is on it tthen you may need to up the speed. follow the wires from the blower to the board if it has multiple speeds then you can isolate the red and put the blue or orange on the heat terminal.
3. the board may have an adjustable fan on and fan off pin selector if it is set up to come on to long or go off to soon it may not be controlling the temp of the heat exchanger properly.
4. I would also suggest checking to see if the orifices and gas valve are set up for your sytem correctly.
these are just simple ideas let me know how things go.