This thing has 3 PIMs and there is a fan-unit between the 2nd and 3rd PIM-s. Inside this fan unit are 3 fans. There is a switch also, which says ON, OFF and AUTO.
When I keep the switch in AUTO, these fans NEVER run. I'm not sure if that's correct. The ambient room temperature is 70F, so it's nice and cold. But still, when I put my palm on the top of the 3rd PIM, above the power supply cards, I sense heat that I don't feel comfortable with. In other words, there is no circulating air that cools the circuit cards.
When I turn the fan unit switch to ON, the fans are running, and they cool down the circuit cards and the top of the 3rd PIN nicely, almost cold to the touch.
I traced some wires and found that there are -what appears to be- some sort of thermo-sensors mounted on the top of the 3rd PIM, just below the top cover. I believe these should sense temperature, and if they consider the temperature too hot, they would activate the fans. Can those sensors ever go bad???
This system is 18 years old now, it's in nice, clean and very good shape in terms of its hardware. Nothing ever failed in it.
It's dual stack, and the other stack has 4 PIMs. It has the same type of fan unit between PIM 2 and 3, and the switch there is set to AUTO, and the fans are running about 60-80% of the time. So that side appears to be working properly. That's what makes me think that the fans in the other stack should also be running, at least some of the time.
Any opinions? Any test I could perform?
When I keep the switch in AUTO, these fans NEVER run. I'm not sure if that's correct. The ambient room temperature is 70F, so it's nice and cold. But still, when I put my palm on the top of the 3rd PIM, above the power supply cards, I sense heat that I don't feel comfortable with. In other words, there is no circulating air that cools the circuit cards.
When I turn the fan unit switch to ON, the fans are running, and they cool down the circuit cards and the top of the 3rd PIN nicely, almost cold to the touch.
I traced some wires and found that there are -what appears to be- some sort of thermo-sensors mounted on the top of the 3rd PIM, just below the top cover. I believe these should sense temperature, and if they consider the temperature too hot, they would activate the fans. Can those sensors ever go bad???
This system is 18 years old now, it's in nice, clean and very good shape in terms of its hardware. Nothing ever failed in it.
It's dual stack, and the other stack has 4 PIMs. It has the same type of fan unit between PIM 2 and 3, and the switch there is set to AUTO, and the fans are running about 60-80% of the time. So that side appears to be working properly. That's what makes me think that the fans in the other stack should also be running, at least some of the time.
Any opinions? Any test I could perform?