RVP MACH 8 A/C Two Blade Fan!

[voltdoc]

Came home to the coach on a nice warm RI fall day a few weeks ago and noticed the front AC blower was on, but there was no noise from the outside fan and there was no coolness coming out of the interior vents.

Upon investigation this is what I found:



So the three blade had morphed itself into a two blade. The resulting imbalance also caused two of the three rubber mounts for the motor to completely shear off and the third was badly torn. Must have made quite a racket when it let go. I asked the cats if they heard anything but they just sat there and looked at me. The metal "hat" bracket that comes with the 3 blade kit had one of the stick on legs ripped free of the electrical box so it obviously took a nice hit. Following that I guess the motor stalled.

Fortunately, there was no significant damage to the cooling fins, that could have been a real mess.

Unfortunately, the motor apparently sat there in a stalled condition for hours.

Fortunately, it was still early enough in the day to give RVP a call and they sent out a new blade kit and three new rubber mounts. Tech said they have never heard of this happening before. He also said motor should be OK since it has an overheat shutdown.

Unfortunately, it took a week to get the parts.

Fortunately, it is just 3 screws to remove the rubber fan motor mounts from the base of the A/C pan.

Unfortunately, those screws come up thru the bottom, so the entire AC unit has to be removed to get to them!

Fortunately, it is just 4 bolts to remove the A/C unit and there is just a rubber gasket sealing it to the roof - no caulking.

Unfortunately, the condensate drain has to be disconnected to lift it up high enough to get to the three screws. It's a heavy bugger.

Fortunately, the fan motor, compressor and everything else worked normally after the repair.

In retrospect, I had a prior warning of the impending failure but didn't recognize it for what it was. About a week earlier the same A/C unit started making a lot of rumbling noises. When I checked it out I found one of the fan motor mount screws had backed out completely leaving it with only two of its three mounts attached and causing the extra noise. I tightened the screw and it seemed fine, but I apparently failed to realize there was some significant vibration going on.

Upon examination of the broken fan, I found the blade that had separated had scuff marks along the edge, but the other two blades did not. From that I concluded there must have been a hairline crack in the blade where it meets the hub and as it started to let go it hit the "hat" bracket.

So the moral of the story is if you hear new rumbling noises from your A/C units check the fan motor mounts for looseness. Also take a close look at the fan blade itself. Hopefully this was just a fluke and is not a systemic problem with the 3 blade fans.

[brobox]

Rob, thank you for the great detailed report. Thanks to your great observation, I will add blue loc-tight to the fan screws when I do my conversion. Thank you for being a valuable member of this forum and helping us all out.

Sorry to hear the repair turned into such a project and I hope it doesn't happen to anyone else.

[dusty56]

Rob you are definitely the pioneer in this AC adventure. Tell the cats to stop messing with the thermostat!

[loisjop]

I posted the same thing about a month ago. The mounts will screw off the little studs and screw the new mounts on without pulling the a/c unit as long as the studs are ok. Unfortunately, I did not think of putting locktite on the new mounts and a week ago the fan came apart like a three dollar watch again. This time the studs had backed out of the mounts and the pan so the a/c unit has to come off. I would definitely put locktite on the studs where they screw into the pan and where the mounts screw on. Not pretty when the fan hits! Noel
Ps. Ours was also the front a/c unit both times. Kinda strange!

Posted Oct 2
I think mine are also quieter Inside the coach. They are certainly no noisier. Mine have been installed for about four months now and I have listened to them inside and out compared to other units and I think they are among the quietest I have heard. One word of warning and it may not be a problem for anyone else, but on my original installation I just used the single washer that was already installed. The clearance seemed fine and they ran fine for a week or so. One day the front a/c started making a louder noise and suddenly the fan hit the shroud. How, I don't know for sure, but it ripped the motor mounts apart, and the fan came apart like a three dollar watch. RVP sent me a new motor, the mounts and the fan. I bought three thicker nylon washers and installed them where the fan was slightly higher than the end of the shaft. Haven't had a problem since!
Just for info if anyone ever has to replace the motor mounts they have nut plates on the bottom of the shroud. Just screw the old ones out and new ones in.

[hawgguy]

Originally Posted by voltdoc

I asked the cats if they heard anything but they just sat there and looked at me.

You know it's their fault - despite the lack of opposable thumbs.


Unfortunately it was a big hassle and a lot of work.

Fortunately you got it fixed.

[hogdriver]

Noel

Based on your experience and VoltDoc would you recommend I remove my shrouds and put some Loctite on those screws holding the new fan blades?

[loisjop]

Originally Posted by hogdriver

Noel

Based on your experience and VoltDoc would you recommend I remove my shrouds and put some Loctite on those screws holding the new fan blades?

Dave, at least for me the last problem was with the screws [studs] that come up from the bottom through the shroud. The motor mounts screw on to them. It appears those screws backed out of the mounts and shroud. I didn't have to remove the a/c unit the first time because the fan hit for whatever reason and ripped the motor from the top of mounts like VoltDocs did. I just unscrewed the old mounts and screwed the new mounts on. I guess where I screwed up was not putting loctite on the studs before I screwed the new mounts on.
This time the a/c unit has to come off because of the screws backing out.
I'm still at a loss as to why the fan hit the first time.
To directly answer your question I'm not sure loctite is needed on the screw that holds the fan on to the motor. However, I did put loctite on that screw.
If you ever have to take the motor off the mounts I would definitely unscrew the mounts and put loctite on the studs and reinstall the mounts. Noel

[kzember]

Yesterday, my 3-month old Mach 8 suddenly started to make a terrible noise. After carefully searching for a possible source, I noticed a gaping crack in the fan hub. After removing the fan, I noticed another fully advanced crack at another blade and a partially advanced crack at the third blade. All of the cracks appeared to have started at the open-ended (bottom) area of the fan hub and at the trailing edges of the fan blades. The top of the fan blade associated with the gaping crack had wear damage from impacting the cover.

This situation seems consistent with other accounts listed on the forum.

One of the fan motor mount stud nuts had loosened.

As this happened on a Sunday, all I could immediately do was to sent an email to RVP, describing the situation and requesting a replacement blade. I have yet to get a response. I can only hope that RVP will act quickly, as possible record-high temps are forecast for today here in South Florida.

I take note of the use of Loctite on the studs and suggest the possible use of Nylok-type nuts as replacements.

[loisjop]

[QUOTE=kzember;2322840]Yesterday, my 3-month old Mach 8 suddenly started to make a terrible noise. After carefully searching for a possible source, I noticed a gaping crack in the fan hub. After removing the fan, I noticed another fully advanced crack at another blade and a partially advanced crack at the third blade. All of the cracks appeared to have started at the open-ended (bottom) area of the fan hub and at the trailing edges of the fan blades. The top of the fan blade associated with the gaping crack had wear damage from impacting the cover.

This situation seems consistent with other accounts listed on the forum.

One of the fan motor mount stud nuts had loosened.

As this happened on a Sunday, all I could immediately do was to sent an email to RVP, describing the situation and requesting a replacement blade. I have yet to get a response. I can only hope that RVP will act quickly, as possible record-high temps are forecast for today here in South Florida.

I take note of the use of Loctite on the studs and suggest the possible use of Nylok-type nuts as replacements.[/QUOTE
Any ideas as to what caused the cracks to develop. Noel

[Nowabeachbum]

Originally Posted by kzember

Yesterday, my 3-month old Mach 8 suddenly started to make a terrible noise. After carefully searching for a possible source, I noticed a gaping crack in the fan hub. After removing the fan, I noticed another fully advanced crack at another blade and a partially advanced crack at the third blade. All of the cracks appeared to have started at the open-ended (bottom) area of the fan hub and at the trailing edges of the fan blades. The top of the fan blade associated with the gaping crack had wear damage from impacting the cover.

This situation seems consistent with other accounts listed on the forum.

One of the fan motor mount stud nuts had loosened.

As this happened on a Sunday, all I could immediately do was to sent an email to RVP, describing the situation and requesting a replacement blade. I have yet to get a response. I can only hope that RVP will act quickly, as possible record-high temps are forecast for today here in South Florida.

I take note of the use of Loctite on the studs and suggest the possible use of Nylok-type nuts as replacements.

I guess we all need to check our installations and start carrying our old fans!

And by the way, I don't think there will be very many who sympathize with you about it being too hot out!

[voltdoc]

Seems to be a clear trend here. My rear AC unit fan blade failed last week too. So that's 2 out of 3 (so far) for our Aspire. This time I was onboard the coach when it began letting go (the cats hightailed it under the couch so I guess I can't blame them this time). You could hear the blade hitting something which I believe was the hat bracket that comes with the 3 blade quiet fan kit.

Shut it down ASAP, went up to look and sure enough other crack in the hub. Emailed RVP last Sunday and they emailed me back on Tuesday indicating they were shipping new blades and mounts.




My first failure was back in October on my front AC unit. As that is the most used AC and the rear is the second most used, I am fully expecting the middle unit to suffer the same fate eventually.

While it's possible in some cases the motor mounts loosen, causing wobble and then the blade fails when it hits something, in both my cases the motor mounts were not at fault. On my front unit, I had just tightened up the motor mounts the week prior to the blade failure. I'm no structural engineer but seems to me the blades are failing due to stress, at least in some cases.

We installed the 3 blade "quiet" kits back in June, probably the first to do so among this forum readership. We are full timers so our AC units ran all summer and now we are in humid FL so they continue operate often. Just mentioning that as perhaps there is a time-in-use element involved before the blades start to fail?

Regarding my front unit failure in Oct, I vaguely recall the new blade sent by RVP looked somewhat different than the old but not sure what was different about it. This time I will compare the new and old blades more carefully.

For my first failure RVP told me this was the first time they had seen the problem leading me to believe it was a fluke, but that does not seem to be the case...

Rob

[loisjop]

[QUOTE=voltdoc;2329374]Seems to be a clear trend here. My rear AC unit fan blade failed last week too. So that's 2 out of 3 (so far) for our Aspire. This time I was onboard the coach when it began letting go (the cats hightailed it under the couch so I guess I can't blame them this time). You could hear the blade hitting something which I believe was the hat bracket that comes with the 3 blade quiet fan kit.

Shut it down ASAP, went up to look and sure enough other crack in the hub. Emailed RVP last Sunday and they emailed me back on Tuesday indicating they were shipping new blades and mounts.




My first failure was back in October on my front AC unit. As that is the most used AC and the rear is the second most used, I am fully expecting the middle unit to suffer the same fate eventually.

While it's possible in some cases the motor mounts loosen, causing wobble and then the blade fails when it hits something, in both my cases the motor mounts were not at fault. On my front unit, I had just tightened up the motor mounts the week prior to the blade failure. I'm no structural engineer but seems to me the blades are failing due to stress, at least in some cases.

We installed the 3 blade "quiet" kits back in June, probably the first to do so among this forum readership. We are full timers so our AC units ran all summer and now we are in humid FL so they continue operate often. Just mentioning that as perhaps there is a time-in-use element involved before the blades start to fail?

Regarding my front unit failure in Oct, I vaguely recall the new blade sent by RVP looked somewhat different than the old but not sure what was different about it. This time I will compare the new and old blades more carefully.

For my first failure RVP told me this was the first time they had seen the problem leading me to believe it was a fluke, but that does not seem to be the case...

Rob[/QUOTE
I can guarantee you that wasn't the only one to fail. I've had three fail, all on the front unit. I first thought it was a mount problem, but now I'm pretty sure the fans are structurally deficient. My old fans ran for almost a year with on problem, but the life of these fans seem to be a couple of months if they run any at all. Like you I'm now in Fl so they run a lot especially up front. My a/c unit has to come off this time due to shearing the studs off.
RVP needs to get a handle on this problem. Hopefully, your new fans have been beefed up. Please let us know. Noel

[757driver]

Was going to order the new blades but I think that I will hold off until they get their problems sorted out.

[brobox]

Originally Posted by 757driver

Was going to order the new blades but I think that I will hold off until they get their problems sorted out.

X2 on that.