The refrigerant lines of an operating system on a hot day should feel(Category: AC & Heat Pump) •   Both lines-cold •   Both lines-hot •  Liquid line-hot, suction line-cold •   Suction line-hot, liquid line-cold •   Both lines ambient temperature

•  Liquid line-hot, suction line-cold On a hot day, when the AC or heat pump is running: • The liquid line (high-pressure line) carries hot, high-pressure refrigerant from the outdoor condenser to the indoor evaporator coil — it feels hot to the touch. • The suction line (low-pressure line) carries cold, low-pressure refrigerant vapor from the evaporator back to the compressor — it feels cold and may even sweat due to condensation.