Where Do You Read Your Grow Room Temp?

I built a grow cabinet and I'm having trouble keeping the 'lights on' temps at acceptable levels. But as I'm moving fans and trying different things to lower the temp I'm wondering where should I even be reading? My canopy reads different than soil level and that reads different from another spot. I'm just wondering, where do you read your temps and what's the acceptable range throughout the grow area.

Right now I have 4 fans. One 6" clip fan pointed at the light and one pointed at the canopy. I also have a 9" desk fan modified as an intake and a 4" inline 180 cfm exhaust fan all to keep a 400 watt MH in a 2'x4'x5' space below 80 F for ONE plant 3 weeks into flower.

With all the addition of the intake fan, I'm able to keep my canopy temp at 74 but there are other parts of the grow area that'll read 90-94.