C402 Captain reported during climb; ice began to accumulate on the wings and the boots did not deploy. The Captain diverted and landed.

Narrative

After being deiced in ZZZ; departed in IFR conditions into known icing conditions (light icing expected). Started picking up ice about 2;000 feet AGL. Climbing to 8;000 feet AGL I deployed the boots when I thought it was approximately 1/2 inch thick. Green ready light did not come on and the boots did no deploy. Checked circuit breakers and none had tripped. Tried again with the same results. With ice continuing to build; I diverted to ZZZ1. Weather was deteriorating in ZZZ. [Requested priority handling] and flew the approach into ZZZ1. I had to do a 360 degree turn to lose altitude (had reached VFR conditions) and landed in ZZZ1. It was a hard landing. Visually checked the aircraft after landing with no obvious damage. All passengers and crew were OK. After passengers were taken care of and phone calls were made; I did another run up on the aircraft and the boots checked normal as they did in the previous ground checks. Mechanical issue not being resolved. To my knowledge the same problem has been written up 3 previous times this winter.