part 1 is the little network room where my office racks are, the AC unit suction port is on the cold side of the racks and far away, right next to its roof tile is a blow vent which is also blowing directly onto the thermostat.

This is causing uneven temperatures, ( I have 3 temperature probes in the room) - I have shrouded the top rack door perforations and remounted the rack helper fans to help blow the hot air up (previously the fan was mounted upside down at the very top) This dropped rack temperatures by 10 degrees easily but the A/C unit cuts out from the T stat which gets too cold from the air blowing on it.

My vague understanding says that the system suction vent should be at the hot side of the racks so it can immediately suck in the hot stack of air rising from the back of the racks - while all blower vents should be blowing to the front of the racks. - Am I wrong here? because the AC contractor that the office uses refuses to swallow my thinking.

Part 2 is residential. - I have lived outside of US and with ducted A/C system, the suction vents were always at the very top and were quite large in area, those ducts then led to the evap unit. My house and nearly all houses I see in US have suction vents on the lower level floors and about one small one on top floors even with a single system. In dubai the house I lived in was 2 floors and had 1 A/C unit which was ducted, the lower floor ducts had fan aids while the top ones did not use such a fan, The house could cool down rather quickly and even out.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)