not sure what's the model of your nexus. but I would try:
1.3.6.1.4.1.9.9.117.1.4.1 - fan status
1.3.6.1.4.1.9.9.117.1.1.2 - power supp[y status
not sure what's the model of your nexus. but I would try:
1.3.6.1.4.1.9.9.117.1.4.1 - fan status
1.3.6.1.4.1.9.9.117.1.1.2 - power supp[y status