How often is it necessary to replace a vaporizer in AC? on 2007 Dodge Grand Caravan

2007 Grand Caravan SXt. AC not cooling, had it checked,could not find leak,topped up freon. Added die. Worked one day, took back. Says needs Vaporizer at back, replace at cost of $1,000 approx., or close off system to back at a cost of $400.00.
Car only exposed to elements minimally for one winter, previously stored in winter.

Asked by for the 2007 Dodge Grand Caravan