AC

Jukebox64 · 03-23-2019, 07:16 PM

While out camping last time my AC compressor stopped kicking on. The fan still works great. Before it stopped working I noticed that my thermostat was acting up.
The unit is a Dometic roof unit and the thermostat it built into the unit.
Any ideas??

**Mr. Dan** · 03-23-2019, 07:18 PM

Quote:

Originally Posted by Jukebox64

While out camping last time my AC compressor stopped kicking on. The fan still works great. Before it stopped working I noticed that my thermostat was acting up.
The unit is a Dometic roof unit and the thermostat it built into the unit.
Any ideas??

Who made the thermostat? ... and what do you mean when you say it "was acting up"?

5picker · 03-23-2019, 07:41 PM

Was it possibly freezing up?

Bluepill · 03-23-2019, 08:08 PM

Year, make and model of your RV?

FYI, lots of Dometic A/C failures in the past few years. Base warranty is 2 years, sometimes they extend it,

Jukebox64 · 03-23-2019, 09:02 PM

I guess I should’ve mentioned that my AC is 10 years old. By My thermostat acting up,I meant that it wasn’t exactly controlling when my AC compressor would come on and turn off properly.
I am almost positive it was not freezing up because it’s been a few days and we are back home and the compressor still does not come on.
I don’t think I need a whole new AC unit, I’m hoping at the very maximum I need a new compressor but I am hoping at the least it is just my thermostat control. But I do not know a lot about all of the workings in this air-conditioner.

cavie · 03-23-2019, 09:06 PM

Quote:

Originally Posted by Jukebox64

I guess I should’ve mentioned that my AC is 10 years old. By My thermostat acting up,I meant that it wasn’t exactly controlling when my AC compressor would come on and turn off properly.
I am almost positive it was not freezing up because it’s been a few days and we are back home and the compressor still does not come on.
I don’t think I need a whole new AC unit, I’m hoping at the very maximum I need a new compressor but I am hoping at the least it is just my thermostat control. But I do not know a lot about all of the workings in this air-conditioner.

Can't get just a compressor for an RV unit. You can replace contactors and fan motors but that's about it.

Flat_twin · 03-23-2019, 09:19 PM

Start capacitor could be bad, Easy repair

Jukebox64 · 03-23-2019, 11:55 PM

Does anyone have pictures of what the start capacitors look like? Even though it sounds like a simple fix since the unit is original in a 2008 toy hauler it would probably be more cost-effective to just replace the whole unit.

Scrapper · 03-24-2019, 12:56 AM

Start capacitors come in various sizes and styles. Attached are 3 designs you will most likely see in RV air conditioners.

Also, here are some YouTube videos showing how to test them. The first thing you want to do is look for loose/missing terminals and examine the capacitor casing over for bulging, cracks or leakage.

How To Safely Discharge Your Air Conditioner Run Capacitor: https://youtu.be/ZTQi5rTJIw8?list=PLn...

How To Make Your Own Capacitor Discharge Tool: https://youtu.be/pVIV905qby0?list=PLn...

Start Run Capacitor Testing Using A Cheap Meter DIY (HVAC/Stereo/Microwave/Electronics) Service

https://www.youtube.com/watch?v=SihpkALJtmE

AC Fan/Compressor Not Working - How To Test /Repair Broken HVAC Run Start Capacitor Air Condition HD: https://youtu.be/19A9lvQ6lIA?list=PLn...

Flat_twin · 03-24-2019, 08:41 AM

Ours was a 13.5k btu Dometic AC. Sorry I don't remember where I ordered it but I do remember it was necessary to remove the old part first, label the wiring, and then compare part numbers and make sure I was ordering the right one.
The old capacitor looked bad and corroded. The symptoms were just as you described. Fan runs fine but the compressor would never run. I could hear the "click" when rotating the temperature knob slowly back and forth but that's all.
A new start capacitor fixed it and cost about $30. Clean the other electrical connectors while the AC cover is off and also clean out any debris, mud daubers etc.

I mention mud daubers because the following year the fan would not run on the same AC unit. It would hum but not spin. I removed the trim panels inside the camper, removed the screws holding the control box in place until I could reach my hand up into the blower passage. I was able to move the fan with my hand and some chunks of mud fell out. They were enough to keep the fan from turning. Once I cleaned out all I could find the fan ran just fine.

Jukebox64 · 03-24-2019, 01:38 PM

Thanks for all the info guys. Mine doesn’t click when I turn the thermostat down all the way.

Flat_twin · 03-24-2019, 02:30 PM

Well, let's talk about not hearing a click. Start with what you're calling a thermostat. Thermostat on the wall or the rotary knob on the AC unit?

The click I'm referring to is coming from the rotary knob temp control on the AC unit. The click is just the circuit opening or closing to tell the compressor to turn on.

As you turn that knob back and forth you should hear it.

Jukebox64 · 03-24-2019, 02:40 PM

That’s what I was talking about, the rotary knob on the unit. I do not have a wall thermostat just a knob that goes from cold to colder on the unit. It does not matter how far I turn it I do not hear anything click nor does the compressor come on.

Flat_twin · 03-24-2019, 02:48 PM

OK, I read again what was posted earlier. Sorry I didn't see you posted the thermostat is on the AC unit. That rotary switch could easily be the problem, not the compressor or the capacitor.

Scrapper · 03-24-2019, 06:42 PM

Quote:

Originally Posted by Jukebox64

That’s what I was talking about, the rotary knob on the unit. I do not have a wall thermostat just a knob that goes from cold to colder on the unit. It does not matter how far I turn it I do not hear anything click nor does the compressor come on.

Can you post a picture of the controls or the make and model of ac. Actually the make and model number would be best as you can still get the documentation. I may have the documentation on my laptop.

I am thinking that the dial is just a temperature control which changes the tension of the bi-metal contacts that turn open/close in response to the temperature. If this is the case it would not click and you should have a on/off switch on the panel.

Jukebox64 · 03-25-2019, 05:53 AM

This is the only pic I have on my phone. It’s a Dometic Brisk Air Duo Therm.
I’m thinking since it’s a 2008 that I should just go ahead and spend the money to get an updated new and better AC.

**Herk7769** · 03-25-2019, 06:06 AM

Quote:

Originally Posted by Flat_twin

Start capacitor could be bad, Easy repair

Yes. This is a real easy fix if you can get the numbers on the can.

Jukebox64 · 03-25-2019, 10:32 PM

Well today is the first day I have actually gone over to the camper since we parked it after our trip. Just out of curiosity I decided to turn on the air-conditioner and see what happened, after turning the cold to cooler knob down just a hair the compressor kicked on. It ran about three or four minutes and started blowing very good cold air. I didn’t think it was froze up because when it stopped working I waited two days before trying to use it again and it was still acting the same way.
So does anyone have any ideas about this?

Flat_twin · 03-25-2019, 10:55 PM

Intermittent problems are even more fun to troubleshoot! =:^0

Our toy hauler is a 2005 R Vision model with the same looking Dometic controls. It is curious that you were turning the knob "a hair" when the compressor came on just as it should. I think your trouble is with that rotary switch. Someone who knows what they're doing can test it with an ohm meter and / or jump the terminals to test it.

A bad start capacitor is more often the problem but I don't know if those can have intermittent issues. I've had two start capacitor failures over the years and both were either working or not. No in between.

**Herk7769** · 03-26-2019, 05:51 PM

Quote:

Originally Posted by Jukebox64

Well today is the first day I have actually gone over to the camper since we parked it after our trip. Just out of curiosity I decided to turn on the air-conditioner and see what happened, after turning the cold to cooler knob down just a hair the compressor kicked on. It ran about three or four minutes and started blowing very good cold air. I didn’t think it was froze up because when it stopped working I waited two days before trying to use it again and it was still acting the same way.
So does anyone have any ideas about this?

Are you using an extension cord to power the camper?

Low voltage can cause the compressor to draw more current than normal. After several minutes, it can overheat causing the thermal circuit breaker inside the compressor to signal a shutdown until it cools off (could be 30 minutes or more).

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