Need to charge dash air system. Which is the low side service valve on compressor. Cummins engine, 325 hp, u270 series.
What year coach? 96 or newer high and low side are not interchangeable you can't get it wrong.
U270 is a 1998 model
It should have a blue cap but may have been removed. The r134a recharge kits will only go on the low side fitting it won't fit on the high side.
Here it is on a 97 8.3.
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