"The last time it acted up i checked and had the 24 volts coming from the thermostat to the board but no voltage from the board to the contactor which is what made me think a pressure switch may be locking the voltage out" I want to be clear about something... When you say "the board", do you mean the control board that sits inside your furnace\blower? If so, that's what I mean as well. That board does a lot of things (including the timed shut-off delay mentioned below) but as far as I know, all it does to turn the condenser unit on or off is sent 24 volts over two lines to the unit, specifically the contactor within the unit. There certainly may be more complicated control systems out there but that's the way traditional A\C systems were set up. In such systems, the control board has absolutely no idea of what any "pressure switch" inside the condenser unit is doing, no idea of whether you have no coolant in the lines, no idea of any sort of problem or situation that might exist within the condensing unit. When that control board wants to turn on the condenser unit, it simply sends 24 volts down those little wires. If you turn your thermostat down far enough to signal that you want the room cooler, the thermostat sends a signal to the control board in the furnace, which then turns the blower on by the coils, and then sends the 24 volts to the condensing unit. If in fact you have "no voltage from the board to the contactor" despite you adjusting the thermostat to start the cooling cycle, then your first concern would be to understand why the board or the wires from the board aren't working properly. If, on the other hand, you mean some sort of control board within the condenser unit itself, one that acts as a second brain (third if you count the thermostat) in the system and takes into account information from within the condenser such as high and low pressure readings before sending the 24 volts along to the contactor, then sure, you might well have an issue with that particular board or the pressure sensors or perhaps a whole bunch of things. Don't know. What I do know is that if you are indeed talking about this sort of internal control within the condenser itself and when you think it should be triggering the contactor but you can't detect any juice between the internal board and the contactor, then your problem isn't the contactor. The only way you can determine whether a contactor is bad is to send 24 volts to it. If you do that but the 220 volt lines within the unit aren't energized, then it's the contactor and indeed, because contactor issues can be all about carbon buildup on the contacts, you might have the symptoms you describe. But if the contactor isn't getting the 24 volts at all, you need to look for another answer. I strongly suggest that you turn this over to a repair tech given that you're no longer talking about replacing a $12 contactor in 15 minutes. Nick in Palm Springs

shutting the air flow off at the supply grill doesn't put the air back into the supply plenum to be redistributed throughout the house. it simply stops it from exiting the duct. the full force is still in the duct. by not allowing it to exit, you can increase the static pressure of the duct system. manual dampers are best located at the plenum. the duct is connected to a duct take off or collar. the take offs either have manual dampers or they dont. you can install them by replacing take off with a dampered take off. but then you have to be sure to reseal (with mastic) the take off to the plenum, set the damper, and reattach the duct..and mastic seal. bring insulation to plenum so that no metal of take off is exposed. I usually put a piece of mastic tape at the damper on the bottom of theduct take off to keep it from viberating. if it viberates it will change the position of the damper over time. mark on plenum which direction to move damper to close. if ducts leak..they leak at any pressure. mastic seal of ductwork is always a good thing. as is sealing supply boxes where they penetrate into conditioned space. I use mastic tape..see attached picture to seal from inside house. best of luck.

I never shuts down with temp setting at all ( both fan and outdoor unit) . " It never shuts off or indoor blower stops with outdoor unit still running, then you do need a new stat." One person on another forum suggested disconnecting the green thermostat wire . He told me that the control board was bad if it still ran . I tried that and it did still run. A thermostat is inexpensive and easy to get but I would like get it right the first time . Could ou please expand on this some more . Thanks

jtw a nice anecdotal story with few facts. let's get some specifics. your location? brand, mdl, age, size of existing system? amount of living area unit serves? home is sgl story or two story? location of ductwork? thermostat setting? average high outside temperature? insulation qualities of home? filters regularly changed? last time system was service? any idea of supply temperature? if not, find out with dig thermometer. how about return temperature? if not find out. why accept this situation without an experienced HVAC pro checking your system out? IMO