Upon arrival tech ran system in heat mode and found condenser to start up but blower did not start immediately. Blower started and system ran shortly before turning off and displaying error code F5. Found F5 to indicate shorted or open compressor discharge temp sensor. Ohmed sensor, according to 50k chart and Trane sensor is bad. Ambient sensor and coil sensor are also made into the same plug. Provided estimate to customer to replace. Customer will call with a decision tomorrow.