Doc Otep,
Nangari na sa akin yan dati. yun hose na yun madalas masira due to vibration of the engine. yun front and back difference eh dahil sa expansion valve. there are two in our patrol, one for each front and back evaporator. so if the front goes kaput you are left with only the rear cooling the cabin and vice versa. medyo nagbabara na yan siguro pero pagnatuluyan yan di na lalamig yan. yun aircon shop near our place tried to blow compressed air and even soak the valve in gasoline pero pag clogged siya talagang throw away na. may times din din na maganda buga ng mist ng expansion valve parang injectors ng diesel engine pag di na tama spray pattern di na siya efficient. HTH