A/C fan issue

[LouLawrence]

My Dometic A/C fan just hums when the thermostat is turned on. I can reach up and spin the fan but there is a large drag. After spinning it a bit 10-20 partial spins it finally starts spinning and runs without issue. Can the fan only be replaced or a bearing that needs lube?

[LouLawrence]

It would not start again today. What I noticed is that with the unit turned off, the fan would not rotate freely. I suspect this goes along with the fact that the fan has a noticeable wobble. I think this takes out the possibility of it being a start capacitor. Will have to find a mobile service person capable of replacing the motor/bearing/fan. Yes, I am at a bit of a loss. It only took one good hand spin of the fan for it to fire up.

[LouLawrence]

Now it's working fine. We turn it off at night and it fires right up in the morning (yes, it's that hot here).

[StirCrazy]

sounds like the capacitor to me. test it, take about 5 minutes once you get the cover off. if it is the capacitor you could splurge and order a soft start and put that in while your at it, or just spend 15 bucks and put the same capacitor back in.

[ScottG]

Just break the fan loose and use it. I had to do that every spring with our Dometic AC and it worked fine until we traded it in 13 years later. A new fan kit will do the same thing after a while.

[wa8yxm]

LouLawrence wrote:
My Dometic A/C fan just hums when the thermostat is turned on. I can reach up and spin the fan but there is a large drag. After spinning it a bit 10-20 partial spins it finally starts spinning and runs without issue. Can the fan only be replaced or a bearing that needs lube?

Yes the blower motor can be replaced.... It's not even that hard to do. But finding a replacement.. That can be a bit of a problem.

A good electric motor shop can do it for you. (Find the replacement)

[ktmrfs]

common issue is the motor bearing(s) (usually some form of oillite bronze bushing) drying out and then making the shaft hard to turn. Now once that happens taking them out, oiling them will provide a fix..... for some period of time. But it will likely happen again.....
On our coleman a fasco OEM replacement motor with correct shaft was reasonably inexpensive. So when our Coleman started to squeal for a while on startup, I just replaced the motor. Good to go.

I looked and couldn't find any motors with sealed ball bearings, would have been better, but the original motor lasted almost 10 years.

[jimh406]

LouLawrencePretty wrote:
I am concerned about the wobble as the other similar unit has a rock solid spin.
Also, where would a start capacitor be and how do I access it?

The Domestic website/owners manual should point out most of the parts.

If you aren't very familiar with electricity, I'd leave that capacitor alone. It may not kill you, but it can give you a jolt big enough to toss you off the roof if you don't discharge it properly.

I think it's very unlikely that's the issue if it started over and over. It's more likely the fan needs greased or replaced. Just running it may have been enough to loosen the shaft/fan up.

[LouLawrence]

I took a closer look from inside and there is also a pretty good wobble in the cage fan. Today it has started without issue. We let the fan run all night last night and we stopped at a rest area. One quick touch and it started right up. Ran for about an hour. Turned it off and finished up our trip, about another 2 hours. Everything fired right up. Pretty concerned about the wobble as the other similar unit has a rock solid spin.
Also, where would a start capacitor be and how do I access it?

[dougrainer]

Check the fan start capacitor. THAT is why they have fan start capacitor. Your post points to a defective capacitor. Doug

[TonyBravo]

Definitely, just grease the bearing and it will go away, if you have spare time you can pay attention to all the bearings, they will thank you for it

[jimh406]

Someone posted in a different thread that they lubricate their bearings every season, so I guess it works for at least one person.