Why is the cooling element of the TPCC cooling housing not activated during commissioning despite the high ambient temperature?

If the peltier cooling element does not work despite correct wiring and a high ambient temperature, the following explanation might help.

There are two bimetal temperature switches inside the TPCC cooling housing. 

If the temperature drops below +30°C or exceeds +50°C, the control current is interrupted by opening the corresponding temperature switch. The output of the SSR thus disconnects the cooling element from the supply voltage.

The last situation described is important if the cooling housing is put into operation at an ambient temperature above +50°C. Cooling remains deactivated until the ambient temperature falls below the upper limit (minus a hysteresis of 10K), i.e. +40°C. If the ambient temperature never falls below this value, this prevents the initial activation of the cooling element. As a remedy, we recommend adding an electrical switch to the wiring shown in the manual. When activated, the switch temporarily connects the 24V supply voltage to the input (+3) of the SSR in order to start cooling manually.  As soon as the internal temperature has fallen below approx. +40°C, the switch must be opened again so that the temperature control functions as specified.

The following drawing shows the wiring diagram from TPCC manual with additional switch.