Diagnostic/ System not keeping up in the night. I arrived and tested the system in main heat mode and pressures were within factory specs. I tested emergency heat mode and the system blew room temperature air. I examined the wiring on the heat strip kit and found that it was receiving the right voltage and signal, but failing to activate. I gave an estimate to replace the heat strip kit and it was approved. I acquired the new kit, installed it, and tested operations. The system is heating properly at this time.