Air Conditioner blowing funny smell out of the vents

[TravelTiger]

Hey all, 2016 Big Country with the Dometic "High Performance" 3311983.000 units, Whisper Quiet ducting inside.

Bedroom unit works great, living room unit, not so much. We owned it 20 months, fulltiming.

The heat in Texas really challenges this unit, struggling to keep at 78 when temp gets over 95.

Today, temps were milder as we have some rain in the area. At 3ish, it was doing fine keeping up. I suddenly noticed a smell like burning electrical, so I shut down everything in the rig. I turned the AC on again, and the smell was coming from the AC vents. Went outside to look around, the outside AC fan was running but the stopped. I went back in, the thermostat looked like it was on, but the indoor temp said 32.

I turned it off and waited about an hour (researching). I turned it on again, temp read 80 inside... the fan came on and then the compressor, the air was feeling cooler, but the smell was there again, so I just turned it off again.

I went on the roof and looked inside the shroud through the vents, and could not see anything amiss. It did smell burnt when I got my nose close to the vents.

I have a mobile tech called, but it will be a week before they can get to me.

Any thoughts on how we could diagnose this and get a solution quicker?


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[SHerrick]

First, I'd be willing to bet you accidentally touched the button, shifting the temp from F to C. 32 C = 89.6 F.

There are eight screws holding the cowl on the shell of your A/C unit. Turn the unit off, pull the screws and reach into the unit with a brass brush and remove the lint buildup. Do the same thing on the outside. Put the cover back on and come back inside. Turn the unit back on and remove all the vent screens and on the delivery ones, remove and wash the foam inserts. Let them dry and keep smelling the A/C as they dry. If it returns, there is something else wrong, but I'm betting that you are smelling roasting dust on the cooling coils.


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[TravelTiger]

I don't have an inside access to the AC unit, it's the Whisper Quiet* style. Only has filters in the vents on the return side. I changed them to clean ones earlier this week.

And no, did not change to Celsius. The AC was showing running, "Cool" and "auto" at 76, but no fan was on. Pressed the inside temp it said 32.

*Whisper Quiet is a a marketing term, not actually quiet as a whisper.


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[SHerrick]

Oh, I know... the one in the bedroom sounds like a freight train. I'll bet this evening, if you run it, it will be fine. I was talking about the external heat exchanger.


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[TravelTiger]

I'll try it tomorrow when hubby can investigate with me. But I know that electrical burning smell, I'm not going to chance it.


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[SHerrick]

Makes sense. Good luck!


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[olcoon]

Erika,
In case you didn't know the AC unit "should" have a 2 year warranty. We had to have ours worked on a few years ago & found this out. Saved us a bunch! You might have to check the paperwork on it.

 

[carl.swoyer]

Possibly loose wires in the mixing box.

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[TravelTiger]

Well, finally we had time to diagnose the AC unit. Here are pics, we found the burning smell source. But not familiar enough to know it's cause or how/what to replace.

Mobile tech will be here Thursday.


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[Jesstruckn/Jesstalkn]

Glad you found the issue Erika
It's possibly was just a loose connection at that termanal, you my be able to just cut that wire back a few inches to find fresh clean wire and splice on a new termanal. Clean the post with a wire brush and then use a little bit of Dielectric grease on it and plug it back in.
That's what I'd do before I payed a mobile tech any money.

Jerrod

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[carl.swoyer]

That looks like a start up solonoid. It holds high amps for starting the ac. You can probably replace it yourself. However disconnect power and there is a static time ? For it to discharge any residual amps. They do make an upgrade for that its a hard start kit. Uses less power on start up. However please verify the part first

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[gregw]

Agree with Carl. Replace both your last picture kinda looks like the device was hot also. Once an electrical device is to hot it will never preform up to spec or it will failure early. Most hard start capacitors are $25-$50. Don't let them charge you $300.00 like I saw on the news!

 

[rjr6150]

Definitely a starting capacitor.

Pretty easy change out our turn off power to that circuit pull the connector off being extremely careful not to touch the two terminals together as these hold a charge. Should be able to go into any electrical supply store with the old one and they will match it up for you.

These type capacitors are only designed to be energized for a brief period at start up. Typically only a few seconds. If this shorted out you they are known to also take out the compressor due to attempting startup.

 

[TravelTiger]

That looks like a start up solonoid. It holds high amps for starting the ac. You can probably replace it yourself. However disconnect power and there is a static time ? For it to discharge any residual amps. They do make an upgrade for that its a hard start kit. Uses less power on start up. However please verify the part first

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According to the parts detail I found, it could be the start motor kit.

Since it could still be under warranty from Dometic, I'm not keen on us doing it ourselves.

I'll call Dometic on Monday and see what they will cover.


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[carl.swoyer]

We'll try to get the hard start kit. It stores more amp s and the ac starts easier. I could remember the part name exactly, but that is what I was talking about. Good luck. I suggest you don't use that ac.

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[carl.swoyer]

According to the parts detail I found, it could be the start motor kit.

Since it could still be under warranty from Dometic, I'm not keen on us doing it ourselves.

I'll call Dometic on Monday and see what they will cover.


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We'll try to get the hard start kit. It stores more amp s and the ac starts easier. I could remember the part name exactly, but that is what I was talking about. Good luck. I suggest you don't use that ac.

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Meant to say I couldn't


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[TravelTiger]

We'll try to get the hard start kit. It stores more amp s and the ac starts easier. I could remember the part name exactly, but that is what I was talking about. Good luck. I suggest you don't use that ac.

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Oh trust me, we aren't using it, and we can tell! Was 104 today, and got up to 93 inside the living area without air. We spent the afternoon elsewhere. We do have the bedroom air and it works great but of course can't keep up with that heat.


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[TravelTiger]

Well, tech came today, it was the start capacitor. He tested the amp draw of the compressor, and said it was correct. This is a common failure, he said. I will file with Dometic warranty and see if we get any reimbursement.


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[TravelTiger]

Well, tech came today, it was the start capacitor. He tested the amp draw of the compressor, and said it was correct. This is a common failure, he said. I will file with Dometic warranty and see if we get any reimbursement.

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[mobilcastle]

With the whisper quiet setup you are loosing a lot of your cooling capacity. I would open up the ceiling and install a cold air dump panel. I did this to mine and I makes a world of difference in keeping the 5ver cool.


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