Render Connection won't Disconnect after false?

I'm just trying to get a rainbow effect and toggling it using v variable wont even disable it. After v == true it is looped forever. How can I fix this? I even searched the web and It still does not help, putting disconnect in the connection loop.

local v == true

if v == true then
    local c
    c = game:GetService("RunService").RenderStepped:Connect(function()
        Part.Color = Color3.fromHSV(tick() % 25 / 25, 1, 1)
        if v == false then
            c:Disconnect()
        end
    end)
end