I am having a problem with the 2nd compressor dropping off for high amps. The unit is not loading correctly. The digital readout always shows the slide valve position at 0. The slide valve solenoid is not getting voltage. The #1 compressor works fine. The I/O board is as far as I can get to with the documentation I have. I don't like being a parts replacer, especially when it comes to expensive circuit boards. I am no electronics wiz but a I would like to determine that the I/O board is getting the correct readings from the main processor board. I belive the compressor is over loading because the control is showing it unloaded but it is fully loaded. From what I gather the solenoid get varied DC volts from the processor to move through the loading steps. Full voltage for unload, no voltage for full load. Any suggestions?