5
Marvair MGA3090-3180 Wall Mount AC I&O Manual 05/2023 Rev.14
Chapter 1 Description & Specifications
1.1 General Description
The Marvair MGA3090A, MGA3120A, MGA3150A & MGA3180A are a series of vertical wall-
mounted air conditioning systems that provide heating, cooling, and ventilation for telecommunication
shelters, and other applications with high internal heat gains. The series is available in nominal cooling
capacities of 90,000-180,000 BTUH. A factory installed economizer, resistance heating elements and
reverse flow configurations are available.
All Marvair MGA wall mount air conditioners feature an exclusive electronic control board or PLC-
based controls.
The control board and PLC consolidate several of the electrical components, improves the air
conditioner’s reliability and has LED’s to indicate operating status and fault conditions to assist the
service technician. A complete description of functions is in Section 1.6
Other standard components include:
• Hot gas by-pass valve to allow operation in cold temperatures
• Thermal expansion valve to improve both efficiency and capacity over a wide range of ambient
temperatures
• Phase monitor to prevent operation if the unit is not properly phased
Marvair air conditioners are designed for easy installation and service. Major components are accessible
for service beneath external panels.
All units have internal disconnects. Depending upon state and local code requirements, this feature
may eliminate the need for an external breaker or disconnect.
