Customer has 5 y/o 2-zone Lennox heat pump,system that operates for whole house. System is not heating properly due to faulty reversing valve not switching over in heat mode. Pressure levels were equalized, despite compressor receiving power. Recommend replacement of compressor with reversing valve for they both can cause failure to each other. Noticed other issues in regard to system. Informed customer of all findings. Emergency heat mode currently being used.