I service freezers, for selling bagged ice. I have seen a run of dusty condensors, and this month, been changing out condensor fans.
With the dirty condensor, the pressures and temps go up. Does that tend to cook the condensor fans? Causing early failure? It seems sensible.
It shouldnt affect the blades unless they are made of tin which alot are , in which case they could get warped somewhat if they are right up to the condensor coils in a shroud and seeing alot of residual heat from the condensor/compressor . Clean the fan blades when you do service on the unit so it moves the maximum cfm.
Heck, you know the motors are cooled by air flowing over them. Restrict air flow and raise its temperature and what do you think is going to happen. The fact that those boxes sit outside in hot weather can also heat stress the condenser fan motor. Funny thing though, the motor may not fail until months after a severe overheating. :-(
TDD
The blades aren't the issue. The problem is that the fan motor bearings get sluggish. The fan over heats, and there is no rotation or air flow.
Nine watts isn't a lot of heat to dissipate. But, you're right, they would have to be air cooled. The dirty condensor blocks the air flow -- both to the condensor and the air over the fan. Both result in higher temperatures. That's how I view it, just wanted to see if anyone else saw that kind of thing in the real world. Thanks.
Whenever I service a unit that has one of those unit bearing motors, I check the free movement of the bearing. I often drill a 1/8" hole in the bearing cover so I can re-oil the felt in the housing. The oil frees up the bearing giving the motor much more life. A bit of silver duct tape over the little hole is a good idea. ^_^
TDD
I've had a few moments when the screws that hold the fan bracket are rotted and won't come out. In that case, I take a hammer and slotted screw driver, and knock the aluminum back off. Spray some cleaner (brake cleaner or carb cleaner) to flush the bearing, and then reoil. It's totally crude, but it delays having to swap out the box.
Been meaning to buy a yellow ink pen like the junk yards do, and date the motors when I install them.
You don't have to knock the back off, the little hole and some turbine oil has always worked for me. You don't have to use solvents, the turbine oil is light enough to penetrate the bearing and extend the life of the motor. The felt in the reservoir soaks oil right up and will hold it without leaking unless the seal on the cap is damaged and the drilled oil hole is not sealed.
TDD
I may try that. The times I can't get the fan out, I could drill the edge of the cover, but can't get at the flat side.
For me, it seems that knock the back off is easier than drilling. I've got the hammer and screw driver on hand, the drill and foil tape are in the van.
If you can get a syringe, a very tiny hole will do for injecting oil. I do it all the time with all sorts of motors. I lube the small muffin fans in computers with a tiny oiler after carefully pealing up the label on the fan.
TDD
Now, that's a good idea. Syringe would allow for a much smaller hole. NYS just took syringes off the prescription list, so now commoners like me (age
18 and up) can buy them.I use syringe to put marine grease into electrical contacts. Plug and socket kind of connections (refrigeration thermstats, etc) I found that Noalox corrodes contacts. Dielectric grease works, also. Bench grinder and make the tip of the metal tube flat. Less likely to stab myself.
I've also oiled muffin fans. First one I did, I sliced the label with a razor. Later, I figured out how to peel them. Amazing what a drop of zoom spout will do.
Go to your local ink-jet refill emporium and buy the blunt needle used for refilling ink-jet cartridges.
Good one! I'd not have thought of that. Thank you.
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