I found this as far as where the Ministry of Labour Office is up in Chiang Mai
It's located in what looks to have been a warehouse just South of the 700 year stadium on Highway 121 (Canal Road). If your heading North on Highway 121 from Huai Kaeo Rd, the left lane of the divided highway ends about
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kilometer south of the Somphot Chiang Mai 700P Rd intersection. Right where the highway ends, take a left into a huge parking lot with a massive warehouse. That's it. Enter the building on the far (North-west side) and up three flights of stairs.
If you have a GPS here are the coordinates: 18°49'58.33"N/98°57'39.54"E