Larry, is that a rolled up newspaper I see? Rreplace the newspaper w/ a piece of wood. You have to remember most fans are built to a price point. Before getting out the tools,Talk to the cook and make sure this is not new problem. If the noise is not new, may be cleaning the fan is not the cause. Find out when the noise happens, on start up, always, on shut down or intermittant. How loud is the noise? Make sure the fan switch is on. You can control the operation of the fan by using the switch at the fan. What kind of noise do you hear, squeeks, rattles, or knocks. Can they live with the noise? or do they really want the noise stopped?
1. BELT The easiest to eliminate is the squeeky/squeling belt. The belt may need replacement, adjustment jor cleaning of the pulleys.
2. WHOOP/WHOOP NOISE this may be caused by a paper towel, dish cloth or take out styrofoam tray that has been sucked up into the fan..
2. RATTLE/KNOCK/SCRAPE The most common noise is the rattle or knock. Turn the wheel by hand, even though this won't usually make the noise. Turn the fan on, watch for out of round. If you hear a scraping noise, feel for clearance between the wheel and the tub. If there is inadaquate clearance, that is probably the noise. You may need to pull gently up on the inner tub ( part with the motor). Look for movement. Sometimes you can tighten the fastners. Other times you may need to adjust the brackets holding the fan together. Sometimes you need to add nuts and bolts, using body washers. Sometimes you can just pull up on the area and that will stop the noise. In severe cases, you may need to change the angle of the fan shaaft. I had one fan that I used a hammer and just increased the clearence between the whell and the housing. The picture shows a newspaper between the brace and the sheet metal? Using a piece of wood in that location may help. Make all adjustments sparingly, never more than what can be undone.
3. FAN BRAND. Some fans are just a POS. That is a technical term for piece of shit. The worst brand is Greenheck, I've got a couple of them I do not tip, as that will put stress on the parts and cause noise. Sometimes adding metal braces to the base will strengthen the fan enought to stop the noise. A fan hinge kit may help also.
4. Sometimes, nothing will help, the customer may just have to live with the noise, or spend $2,000 / $2500 for a new fan.
Douglas Hicks
General Fire Equipment Co of Eastern Oregon,Inc