So this is not going to fix your AC issue, improve performace but not fix it. Are you running the Ford Air By itself and the starcool off? You have to have the starcool on when running the front air.
"For clarification on the Starcool switch/Starcool operation. It is good to have the Starcool Blower switch set to "low, med, or high", so that you can operate the Starcool Evaporator without getting out of the driver's seat using the "on/off" rocker switch being discusssed. I would not however, recommend leaving the Thermostat set to "cool" as you could inadvertently place the inverter in an overload condition, or restrict the flow of refrigerant to the dash Evaporator.
Remember that the Thermostat, when switched to "cool", will only control the 110volt Starcool compressor, the lower Starcool Condenser Fan, and the Starcool Solenoid valve. The Thermostat has nothing to do with operating the Starcool Evaporator while using the engine driven compressor. It is very important to have the Starcool Blower switched to at least "low" whenever operating the dash A/C so that proper refrigerant balance between the systems is maintained. If you forget to turn the Starcool Blower "on", you'll notice the temperature of the air coming out of the dash vents getting progressively warmer.
I have seen times when a Factory Ford fuse that is suppose to provide 12 volt "ignition on" power to the Starcool Relay Plate be bad, thereby allowing the Starcool Solenoid Valve to close whenever the Thermostat is set to "cool". If this happens, you will have no refrigerant going to the dash Evaporator and will not get any cooling out of the dash vents, but you will get cooling out of the Starcool Evaporator.
Also, if you leave the Thermostat set to "cool" you can overload the Inverter. Let's say you're using the inverter with the engine running and the Starcool is "on". If the Thermostat is set to "cool", then when you turn the engine "off", the Starcool Compressor will try to operate through the Inverter and most likely send it into an overload mode. This could be avoided if you turn the "on/off" rocker switch "off" first, but you may not always remember.
Jage, sorry for taking this to another level, but you know how I like to give as much info as possible. Please move it wherever you feel it needs to be.
Hope it is a simple as this.