Having Fan problems...help!?

[armymedic]

I need some of your rocket scientists advice. My fans on my really nifty AIO jbj with metal halides are coming on sporadically, less and less. Which in turn is leaving the MH light to auto turn off. The light will only stay on about 10 minutes until it heats up then shuts off. What would cause all 4 fans to not turn on? Over the last few days i have heard a fluctiation in the speed of the fans but i can not find anywhere whether these are variable speed fans which would cause them to run at different speeds.

[Coral Hind]

I would open it up and check the connections. I would also take a can of compressed air and blow them off.

[SeanH]

I need some of your rocket scientists advice. My fans on my really nifty AIO jbj with metal halides are coming on sporadically, less and less. Which in turn is leaving the MH light to auto turn off. The light will only stay on about 10 minutes until it heats up then shuts off. What would cause all 4 fans to not turn on? Over the last few days i have heard a fluctiation in the speed of the fans but i can not find anywhere whether these are variable speed fans which would cause them to run at different speeds.

 

Open up the unit and spin the fans manually. If the fans all spin easily and rock slightly when coming to a stop, then they are physically good. If they don't spin easily the bearings are shot and you need replacements. The other option is the power source for the fans is bad - use a multimeter set for DC and check the voltage going to the fans. I don't know the voltage you should have on that fixture, but I would assume it would be 12 volts DC. It's not likely that all fans would fail due to a physical wiring fault if the thing is designed properly, but there is a lot of heat in a light fixture, so it's possible you could have a melted wiring harness. Trace all the wires and make sure they aren't melted and shorting to the frame. Make sure you unplug the light for this.

 

BTW, it would make no sense for variable rate speeds for fans on a light fixture, if you think about it. The lights produce the same amount of heat all the time, so there would be no point. It wouldn't make a lot of sense even for multiple bank lights as the fixture would go from hot to hotter'n'H-E-double hockey sticks as lights turned on. I could see banks of fans associated with lights, but I think that it would be a silly design, too. Most of the light fixtures I've seen so far are not well thought out for heat dissipation and control.

Edited October 13, 2010 by SeanH

[gwweber]

ha sean i used dell computer fans on my light and they spun so fast i cut them down to a 5 volt power supply and the light stays very cool tried a 7.5 volt first and they still spun too fast. Those Optiplex 960 fans are a beast LOL

It is a currennt fixture and the original fan would turn on and off as if it were thermostatically controlled, I dont think it was working right as one of my ballasts had burned out and looked like it was very hot

[Integral9]

Sounds like a sporadic short circuit. I would check for loose wires first. Then disconnect one fan at a time to see if the problem persists. The short could be internal to a single fan, but effects the whole circuit.

[armymedic]

well....i took the entire canopy apart to day and just re-tightened every wire i could find. Took the ballast apart and did the same. put it back together and it is working like a champ. What did i do to fix it? have NO idea. Musta been a loose wire?? But thank you all for your insight!!!

[Coral Hind]

I'm glad you got it working now.