Hi,
Please forget the Mohamed's answer.
You have to use the restrictions on the shipping methods.
You can set a minimum and a maximum price for the shipping method configuration.
So, you will have one (or more) "no-free" shipping method with a maximum price restriction
And a "free" shipping method with a minimum price restriction.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.