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Question 1: There are 5 fields that apply to the amount of outdoor air.

1) Minimum Outdoor Air Flow Rate 2) Maximum Outdoor Air Flow Rate 3) Minimum Outdoor Air Schedule Name 4) Minimum Fraction of Outdoor Air Schedule Name 5) Maximum Fraction of Outdoor Air Schedule Name

Since this is a 100% outdoor air unit, I assume the minimum and maximum outdoor air flow rate fields are set to the same value. Try using the same schedule for 4) and 5) above and see if you get the variation needed. 3) above would apply to modulation of outdoor air when economizer is used. I would also use the same schedule here as well.

Question 2: Regarding MAU, I assume this refers to the ZoneHVAC:OutdoorAirUnit. I would expect this system type to control using the zone outdoor air flow rate specifications.

Question 1: There are 5 fields that apply to the amount of outdoor air.

1) Minimum Outdoor Air Flow Rate 2) Maximum Outdoor Air Flow Rate 3) Minimum Outdoor Air Schedule Name 4) Minimum Fraction of Outdoor Air Schedule Name 5) Maximum Fraction of Outdoor Air Schedule Name

Since this is a 100% outdoor air unit, I assume the minimum and maximum outdoor air flow rate fields are set to the same value. Try using the same schedule for 4) and 5) above and see if you get the variation needed. 3) above would apply to modulation is used to modify the minimum and maximum outdoor air flow rate input field fraction to dynamically adjust the minimum outdoor air quantity. The reason there is a check for an air loop is because the actual system flow rate may be different than the maximum outdoor air flow rate specified in 2).

The Minimum Outdoor Air Schedule, 3) above, is used to modify the fraction of outdoor air when economizer is used. I would also use the same schedule here based on the inputs in 1) and 2) as well.

// set OutAirMinFrac
if ( AirLoopNum > 0 ) {
if ( AirLoopFlow( AirLoopNum ).DesSupply >= SmallAirVolFlow ) {
    OutAirMinFrac = MinOAMassFlowRate / AirLoopFlow( AirLoopNum ).DesSupply; (kg/s)
} else {
    OutAirMinFrac = 0.0;
}
} else {
if ( OAController( OAControllerNum ).MaxOA >= SmallAirVolFlow ) {
    OutAirMinFrac = MinOA / MaxOA; (inputs in m3/s)
} else {
    OutAirMinFrac = 0.0;
}
}
if ( OAController( OAControllerNum ).MinOASchPtr > 0 ) {
MinOASchedVal = GetCurrentScheduleValue( OAController( OAControllerNum ).MinOASchPtr );
MinOASchedVal = min( max( MinOASchedVal, 0.0 ), 1.0 );
OutAirMinFrac *= MinOASchedVal;
}

if ( OAController( OAControllerNum ).MinOAflowSchPtr > 0 ) {
MinOAflowfracVal = GetCurrentScheduleValue( OAController( OAControllerNum ).MinOAflowSchPtr );
MinOAflowfracVal = min( max( MinOAflowfracVal, 0.0 ), 1.0 );
if ( MinOAflowfracVal > OutAirMinFrac ) {
    OutAirMinFrac = MinOAflowfracVal;
}
OASignal = max( MinOAflowfracVal, OASignal );
}

if ( OAController( OAControllerNum ).MaxOAflowSchPtr > 0 ) {
MaxOAflowfracVal = GetCurrentScheduleValue( OAController( OAControllerNum ).MaxOAflowSchPtr );
MaxOAflowfracVal = min( max( MaxOAflowfracVal, 0.0 ), 1.0 );
if ( MaxOAflowfracVal < OutAirMinFrac ) {
    OutAirMinFrac = MaxOAflowfracVal;
}
OASignal = min( MaxOAflowfracVal, OASignal );

Question 2: Regarding MAU, I assume this refers to the ZoneHVAC:OutdoorAirUnit. I would expect this system type to control using the zone outdoor air flow rate specifications.