Pag sa ilalim ng dashboard galing yung hissing sound, evaporator or some call it the cooling coil fins. May napansin ka bang kakaibang amoy sa loob ng sasakyan? Normally, the evaporator costs 3000-5000 depending on what model your ride is. Plus the freon, labor, drying unit which adds up. May evaporating units like sa Pajero which are laminated types that cost 12000 each.

HTH