Basement AC/Air Duck Fan Motor not working

[Fultimn]

I have a 2000 Beaver Marquis, I know this is a Monaco Forum but Monaco owned Beaver before they folded, also the older Holliday Rambler Navigators had basement ACs. My unit was mgf. by SCS (Specific Climate Systems) Frigette who are also out of business. The Co was bought out but the new Co. did not buy the A/C business. Don't know where their parts/assets went to. My problem is that the fan that blows cool air through the exchanger to the coach air ducks will not come on when the system is in Low Cool Mode. Tried changing the fan control on the thermostat from Auto to Manual Lo then to Hi, still no fan control. However, when I switch the A/C mode to High Cool Mode, the air duck fan will come on and run, but this only happens after the second compressor kicks on. Both compressors and the condenser cooling fan are OK. Need schematics/source for parts if available like thermostats and control boards etc. Thanks, fultimn.