I have a Lennox ec10 model but no manual or guide can I have skismatic of the model ,I have a switch on the top which I don't know what it is for?

The EC10 model has been made for many years so I suggest you contact Lennox with your complete model and serial number so you can obtain the exact manual for you unit.

As far as the switch on the top it could be a high limit control but that is just a guess on my part. The only time you have to mess with that SAFETY device is if it tests defective.

On the Lennox EC-10 model, this switch will activate manually the air blower and, if installed on your furnace, the electronic air filter, giving you the possibility of having non-stop air circulation and filtration throughout your house.

The other position of that switch will leave the activation of the air blower and the filtration controlled by your house thermostat.