Compartmentalized transport refrigeration system

Claim 1

In a compartmentalized transport refrigeration system having front and rear compartments, first and second access doors to the front and rear compartments, respectively, first and second thermostats which respectively control the temperatures in the front and rear compartments to first and second set point temperatures via null, heating and cooling cycles, a host refrigeration unit which includes a compressor driven by a prime mover in a selected one of high and low speeds, a condenser, a receiver, a local evaporator for the front compartment, hot gas, liquid and suction lines, and a host evaporator damper, a remote refrigeration unit including a remote evaporator for the rear compartment, with the remote evaporator unit being connected to the host refrigeration unit via remote hot gas, liquid and suction lines, and electrical control for controlling the operation of the host and remote refrigeration units, the improvement comprising: a door switch mounted to be responsive to the position of the first door, and control means in the electrical control connected to be responsive to said door switch such that said door switch, when the first door is open, causes said control means to modify the operation of the transport refrigeration system by operating the host refrigeration unit in null and by cycling the remote refrigeration unit between heating and cooling modes to maintain set point in the rear compartment.