A method for measuring a fluid level in a tank containing a fluid for a transportable temperature controlled space. The method includes providing a temperature control system for the transportable temperature controlled space, providing a fluid level sensor for sensing a fluid level in the tank, generating fluid level signals with the fluid level sensor indicative of the fluid level in the tank, providing a fluid level algorithm for receiving the fluid level signals from the fluid level sensor and computing the fluid level in the tank, and inhibiting nondeterministic fluid level signals from being introduced to the fluid level algorithm.