400-IO Control Board

Micro-Air, Inc.


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400-IO - Drop in replacement control board for Dometic™ Marine Air™ Passport IO™
A redesigned, newly manufactured, replacement control board. Drop-in compatible with existing electrical boxes.
Guides & Information

Before You Buy
This board replaces Marine Air and Dometic Passport IO series power supplies. Board mounted parts and layout changed over the many years since the first version of this board was manufactured however, several features of this Board can be used to insure this is the correct board for your application. All models of these boards to be replaced by the 400 I-O have a nine-digit bar coded serial number starting with either 372 or 400. There are also board markings with PCB-372 or PCB-400 written somewhere on the board if the serial number cannot be found. The terminal block always has the outputs in the same order and there were always three sensor jacks and one 8-pin display jack on the board.

Note: Some early models of the Passport I-O series featured a heat relay that was not usually used. If your application does use this relay, the board must be replaced with our Unity Control Board Model ASY-501-09-BL and an external heater triac.

Note 2: If your board number or serial number starts with 310 or 300, please see For replacing Passport II, ECU, or Cabin mate control systems for more details and components available from Micro-Air for replacements.


The 400-IO Control Board is a fully-compatible replacement for the Passport® I/O Control Board from Marine Air Systems®.
- Display and other Jacks are all on the top.
  • Replacement Marine Air Systems® Passport® I/O Control Board
  • New Control Board Redesign
  • Backward-Compatible to Legacy Marine Air Systems Passport I/O Control Board
  • Footprint-Compatible to Legacy Marine Air Systems Passport I/O Control Board
  • Newly Manufactured

Benefits of the 400-IO - Drop in replacement control board:
  • Marine Air Systems® Passport® I/O Control Display
  • Completely new designed and manufactured board.
  • Replaces boards with original serial numbers starting with 372.
  • Fully function and footprint compatible with original design
  • Can also be used with our ASY-402 display to completely replace an older Passport II™ control board (Display keypad must be replaced when replacing the control board.)

Vendor Part #: 4220020 (Dometic) Comparable To Part #: ASY-400-X02 (Micro-Air) Vendor Part #: 4220058 (Dometic) Comparable To Part #: ASY-400-P08 (Micro-Air) ** Obsolete Part #: ASY-372-P08 **

H-2: Works Only with these models:
  • VTD
  • VCD
  • CSD
  • SVCD
  • CMCD
  • SCMCD, and AH Passport I/O