Freezer compressor fan

Discussion in 'The Projects Forum' started by strantor, May 9, 2013.

  1. strantor

    Thread Starter AAC Fanatic!

    Oct 3, 2010
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    This goes out the appliance repair guru/s (you know who you are)

    I've got an old dinosaur of a freezer and it stopped working last night. I moved all the food to other places so I have time to do whatever needs to be done.

    When I was cleaning out the freezer last night, the light came on but that's it; compressor and fan were not working. I noticed that the compressor fan blade was seized against its shroud in one spot; I could force it to do a revolution but then it would stop again. I assumed this was the cause of the failure.

    This morning the freezer was running again, plenty cold inside, but the fan was still seized. Now I can feel the fan motor is very hot and smells, and there's a 60Hz hum in it that wasn't there last night.

    So I assume that at a minimum, this fan needs replacing, but I have 2 questions:
    1. would this fan failing cause undue stress to other components (namely compressor) that would cause them to also fail in short order after having replaced the fan?
    2. does the fan have to be a direct replacement? I have a 6" 120V muffin fan I could throw in there, but I'm suspecting that the air flow might be a calculated value and too little flow causes failure A and too little causes failure B.
     
  2. wayneh

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    I'm no pro but I've repaired my share of appliances through my years. So take my 2¢ with a grain of salt.
    IMHO, no, the rest of the system should be fine. There are probably a couple of thermal cut-outs that are meant to protect the system, and if these have not blown, you should be fine. The whole system is obviously just as old as the fan, so it's always a tough call when to invest more money or not into an old appliance.

    In theory no, it just needs to fit the space and move the air. You can buy a motor with a similar power rating that runs at the same rpm (can you tell what that is for the original?), attach the original fan blades to it, and away you go.

    This last winter I spent a long time trying to find an exact replacement for my daughter's furnace fan motor. I had some success, but it was cold weather and we decided to just pay the service guy to put one in ASAP. I wondered how he could possibly have just the right motor in stock. He didn't, he just pulled a generic one out of his truck and made it work. My point is that exact replacement doesn't matter - if it has the power and the rpm, the air will move.
     
  3. gerty

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    Aug 30, 2007
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    The fan went out in our shop refrigerator here at school. We replaced it with one from an old PLC cabinet that was donated to the school. That was 2 years ago, still running.
     
  4. strantor

    Thread Starter AAC Fanatic!

    Oct 3, 2010
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    I guess I was a little paranoid about the fan. I've had several bad experiences with refrigeration systems (automotive AC) and come to the conclusion that, at least as far as the coolant loop itself is concerned, it is both an art and an exact science. I wasn't sure the required exactness extended into the surrounding parts.
     
  5. Andreas

    Active Member

    Jan 26, 2009
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    Out of interest, what do you think caused the fan blade to seize against the shroud - Is it or the blade deformed or is the motor shaft bent or are the motor mounts loose?

    Do you think that the protection (thermal) fuse assuming it has one could be a resetable type?

    Good luck with it and I hope you find the parts you need.
     
    Last edited: May 9, 2013
  6. JohnInTX

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    Jun 26, 2012
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    As wayneh said, most of this stuff is pretty generic. Grainger has lots of it and this outfit has it all. They probably have an outlet in Houston.

    Good luck.
     
  7. crutschow

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    Mar 14, 2008
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    The new fan motor power rating should be at least as high as the old one. Higher is OK but not lower.

    A muffin fan is not likely to have sufficient air flow to cool the condenser properly.
     
  8. #12

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    I'm taking a break from AAC, but for you I'll login.

    This is my day job so I speak with authority. The compressor is desperately dependent on that fan. It will melt in not more than a few weeks if you run it without the fan. The original fans are labeled as 9 watts if this is what I'm used to seeing. 6 inch, 4 blade propeller fan on a round cast iron shaded pole motor. It isn't much, but it's important.

    Let 9 watts be your benchmark. A 12V muffin fan at .35 amps is only 4.2 watts. Kick it up a notch.
     
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  9. strantor

    Thread Starter AAC Fanatic!

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    Sorry; didn't realize you were on sabbatical. But I see the bat signal is still working though; that is comforting.

    Well I'm a big dummy. I climbed behind the freezer and took pictures and everything and was planning how to go about my fan swap. I bench tested the muffin fan, attached leads to it, and climbed back there with my tools ready to go, when I noticed that the only thing wrong with the fan was a bent blade. No idea how it got bent, unless a mouse committed suicide in there. Straightened it out and we're good to go. It seems so obvious now, especially re-reading my description of the problem - that's the first thing I should have checked.

    And to think some people would have gone out and paid $750 for a new freezer!

    P.S. to add to your compendium of home appliance knowledge, this old ('70s/'80s) Kenmore 19.6ft^{3} freezer only had a 2W fan. It put out just as much or more wind as my 7W muffin fan though; maybe under rated.
     
  10. #12

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    Once upon a time, a friend of a friend said he'd give me a $125 auto-winder for my camera if I fixed his refrigerator. I pulled the Styrofoam packing peanut out of the fan and collected my pay:p

    Part of what's going on is, "efficiency" of the fan. A big, slow propeller will outclass a small fast fan any day. (I still don't know why they saved 7 watts on a fan motor while using a compressor that is so inefficient that it is illegal now.)

    ps, take this opportunity to clean the dust bunnies out and scrub the defrost pan. Use a brush, compressed air, hair brush taped to a yard stick, whatever. I have an "Appliance" brush, 3 feet long and about 1&1/2 inches skinny, $11. It fits behind the coils. The dust bunnies are at war with the fan. If they win, the compressor melts.

    pss, the first symptom of a failed fan is that the temperatures in the freezer will not go low enough. In a refrigerator, the first symptom is that the ice maker stops working. People think the ice maker is broken but it is just refusing to trip until it sees zero degrees F. This is a good reason to keep a cheap thermometer in the freezer. Even if it isn't accurate, you will notice when it changes by 20 degrees and that indicates a fan failure.

    psss, Will keep watch for the bat signal as long as I'm not out of town on a job.
     
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  11. strantor

    Thread Starter AAC Fanatic!

    Oct 3, 2010
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    Turns out that's probably how the fan blade got bent - dad just did this last week.

    This reminds me; I bought a "kill-a-watt" months ago to measure the consumption of some of our aging appliances, including this one. I never got around to using it; distracted, you know, and lazy. So having the freezer out from it's cubby, I went ahead and plugged it in. 60W continuous when the compressor is off, and 400W when the compressor is on. I asked him how much the compressor is on, and he says "most of the time." Using 75% on time and 25% off time, @ .11c/KWH, I calculate that this thing costs $304/yr to keep food cold. ~2800KWH/yr... The new $750 freezer consumes only 685KWH/yr, $75. A new freezer would pay for itself in just over 3 years.
     
  12. strantor

    Thread Starter AAC Fanatic!

    Oct 3, 2010
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    I'm going to leave the kill-a-watt plugged in for 24hrs and see if I can confirm the 75% claim.
     
  13. wayneh

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    A 3-yr payback time is pretty darn good on an appliance likely to last 20. Makes me wonder about mine. ;)
     
  14. strantor

    Thread Starter AAC Fanatic!

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    I give the kill-a-watt a good review. Lots of nifty features. I think it was $23 from amazon or eBay.
     
  15. #12

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    If you buy a new freezer, try to get one that doesn't have a condenser fan. Reminds me of a conversation with my sister. She thought the machine was built better because it had a fan. No, the ones that are built better don't NEED a fan.

    What's eating 60 watts when it isn't running the compressor? Defrost timer? Electrical anti-condensation heaters? (You probably didn't know they had heaters around the doors.)

    Old tricks: If it has external coils on the back, throw a chunk of two by four behind it so nobody can push it against the wall. This way, the coils can't touch the wall and block the air flow on one side. Apply Vaseline to the door gasket, on the hinge side. That keeps the gasket from folding under when you close the door. I always prefer simplicity to gadgets. The more electronics it has, the more repairs you will do. The old freezers with nothing but a compressor, a thermostat, and a light bulb last 30 or 40 years. A defrost circuit will break about every 20 to 30 years. Through the door water dispensers with crushed ice and climate controlled sub-sections will make a nuisance of themselves. KISS
     
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  16. #12

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    It is not just common to calculate a payback period, I do it for every job. In fact, there was one year, right after the Feds demanded a minimum efficiency of 10 S.E.E.R for central air conditioners, that I refused to install any because the manufacturers jacked the prices so high that I couldn't calculate a payback period. (The next year, the prices were reasonable again.) I have no doubt you can calculate a payback period for freezers despite the fact that I don't sell freezers and haven't done the math. As much as I hate to throw working machines in the dump, they have become so much better in the last 15 years that it is more economical and ecological to dump the energy hog and reduce the coal and oil being burnt to make electricity.
     
  17. edwardholmes91

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    Feb 25, 2013
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    Interesting thread, I found the payback times for energy savings etc. really interesting and certainly something worth considering. I built a bit of a big beastie computer the other year. It has a 150cm and two 120cm case fans, a processor fan and also a graphics card fan and it runs so quietly you can hardly hear it, because they run nice and slow. Admittedly if I am doing something like rendering a video then they will speed up a little bit, but other than that it is very quiet and low power consumption on the scale of things.
     
  18. wayneh

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    Not long ago I considered using an old computer to host a friend's website. Even a 15-yr old computer is more than adequate for that task. But even without the monitor I calculated that the electricity bill to run the computer 24/7 would be more than what I had to pay GoDaddy to host the site.

    I also hate junking equipment that runs as well as the day it was brand new, but I hate wasting money even more.
     
  19. strantor

    Thread Starter AAC Fanatic!

    Oct 3, 2010
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    So after 15.37 hours (timer started AFTER freezer got to temp) of running 3ft away from the wall with clean coils, no load (nothing in the freezer) and good seals, kill-a-watt says we used 5.11KWH. That works out to 2908KWH/yr. Working backward from there, I find that the compressor is actually on 80% of the time. The new freezer will pay itself off in 3yrs and couple weeks.

    I hate throwing away "perfectly good" stuff more than anybody. That's why I don't throw it away if I can repurpose it. I've been looking for some sort of structure to make a sandblasting cabinet. I was eyeing the dead barbecue pit, but there just isn't much room in there. This freezer seems plenty big. If that doesn't work out, it could make a garage hazmat cabinet as-is. I've always wanted to play around with a compressor like that, and the condense/evap coils should come in handy when I finally get back around to my ethanol experiments. So it's not all sad news :).
     
  20. #12

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    Nov 30, 2010
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    Be careful with that compressor. It doesn't have much capacity but it can go past 400 psi without stalling, maybe even 600 psi. (I've never had enough stupidity to find out.) If you use it for a compressor, you must absolutely, positively, have a safety valve on the receiving tank in addition to a pressure operated electrical switch. And, if you use it for a compressor, it will fill up with atmospheric water eventually. Still, it'll do for a while.

    I made an air compressor out of a freezer compressor and it was good enough for about 5 years. Then I made one out of a 2HP air conditioner compressor. Worked just fine. Then I realized that the 2HP compressor was inconvenient and I replaced it with a $99 Harbor Freight compressor. It's a lot noisier but I don't have to be maintaining it all the time, replacing the oil it coughed out and checking to see if it's full of water. Just peek at the oil level window every once in a while and complain about how noisy it is. I should have piped it to the other side of the shed so I could put it outside on the concrete.
     
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