AC Not Working July 06, 2022, 01:24:31 pm Went to do a monthly exercise of the generator. After warm-up, I tried to turn the AC on for a load but it wouldn’t start. I could hear the generator slow down as the AC tried to start, and inside I can feel the AC unit vibrating as if it wants to start but no success. On top, I can hear the unit humming so it’s getting power. How should I proceed? Thanks!
Re: AC Not Working Reply #1 – July 06, 2022, 01:53:40 pm If it were mine, I would first plug it into good power source from the house electrical and see if it'll start. If it starts at least you know it's not the air conditioner. If it doesn't start, check all the electrical connections in the converter panel especially the A/C breaker and at the A/C connection. All looks good there then go onto the roof and pull the shroud and check connections in the unit's control box. Look at the capacitor connections make sure nothing is burnt. Look at the run capacitor is it swollen does the fan motor run? Has it been a while since it last ran did it act up then? Lastly or first, don't cycle it on or off too quickly. Give it time to equalize pressures before you try to restart. Jon 1 Likes
Re: AC Not Working Reply #2 – July 06, 2022, 02:14:03 pm Quote from: JonS - July 06, 2022, 01:53:40 pmIf it were mine, I would first plug it into good power source from the house electrical and see if it'll start. If it starts at least you know it's not the air conditioner. If it doesn't start, check all the electrical connections in the converter panel especially the A/C breaker and at the A/C connection. All looks good there then go onto the roof and pull the shroud and check connections in the unit's control box. Look at the capacitor connections make sure nothing is burnt. Look at the run capacitor is it swollen does the fan motor run? Has it been a while since it last ran did it act up then? Lastly or first, don't cycle it on or off to quickly. Give it time to equalize pressures before you try to restart. JonIsn't the AC hardwired into the system or does it use a regular plug? Just wondering how you would plug it into another power source in the house portion of the RV?
Re: AC Not Working Reply #3 – July 06, 2022, 03:35:52 pm Quote from: brewersarcade - July 06, 2022, 02:14:03 pmIsn't the AC hardwired into the system or does it use a regular plug? Just wondering how you would plug it into another power source in the house portion of the RV?What Jon S is saying is to plug the rig (not the AC itself) into shore power and then try to start the AC. If it fails to go, then it’s likely a problem with the AC unit. If so, I would guess a failed start capacitor. BTDT. — Jon
Re: AC Not Working Reply #5 – July 06, 2022, 05:12:35 pm Jon and Jon, I will try that next, thanks! This is the first time it has failed to start. 1 Likes
Re: AC Not Working Reply #6 – July 06, 2022, 08:20:04 pm Greg, low voltage is a killer on any 110 volt refrigeration system. If you could check the incoming voltage when the A/C tries to start it would tell you allot.Jon
Re: AC Not Working Reply #7 – July 06, 2022, 09:25:04 pm Quote from: Jon & Loni - July 06, 2022, 03:35:52 pmWhat Jon S is saying is to plug the rig (not the AC itself) into shore power and then try to start the AC. If it fails to go, then it’s likely a problem with the AC unit. If so, I would guess a failed start capacitor. BTDT. — JonAhhhhhh gotcha.
Re: AC Not Working Reply #8 – July 06, 2022, 10:29:05 pm Quote from: JonS - July 06, 2022, 08:20:04 pmGreg, low voltage is a killer on any 110 volt refrigeration system. If you could check the incoming voltage when the A/C tries to start it would tell you allot.How would I do that Jon?
Re: AC Not Working Reply #9 – July 07, 2022, 02:44:37 am After low voltage blew out our LD's A/C starting capacitor three summers ago and burned a terminal off the A/C's control switch two years ago, last summer I installed a soft-start device on the A/C. It eliminates the large startup surge and allows the A/C to start with low line voltage. No problems since.Home - SoftStartRVWe discovered an extra benefit on our late spring trip this year. On hot nights when sleeping with the A/C on, the banging or bumping that occurs when the compressor starts up is reduced or eliminated. When the A/C's compressor now starts, the soft-start ramps the power up relatively slowly, producing less noise. It's a good upgrade if you camp where only a 15-amp plug is provided and the A/C is needed.Larry 2 Likes
Re: AC Not Working Reply #10 – July 07, 2022, 09:45:51 am Thanks, Larry. That’s one of the upgrades I’ve been thinking about (along with the Fridge Defend product). Was the Softstart pretty straightforward to install? Which Softstart version did you get? 2 Likes
Re: AC Not Working Reply #11 – July 07, 2022, 12:49:06 pm I used a SoftStartRV SoftStartRV, The Amazing SoftStarter for RV A/C's – SoftStartUSAI didn't find the wiring to be difficult but I have done electrical projects for the last six decades.It does require finding the correct wiring diagram from SoftStart's website and applying it to the wiring inside the A/C's plastic roof cover. As an example, this is the wiring instructions for a Dometic Duo-Therm A/C.https://www.softstartrv.com/wp-content/uploads/2021/07/Softstart-Dometic-Duo-Therm-Straight-AC-NO-CUT-Install.pdfYoiur A/C is probably a different brand or model and may be wired differently, find the correct schematic here.Dometic Wiring Diagrams and Instructions Identify Your Model - SoftStartRVLarry 1 Likes
Re: AC Not Working Reply #12 – July 07, 2022, 01:02:16 pm OK, just ordered, $319 and free shipping. Thanks!Going to move the RV next to the house this morning and investigate while plugged in so will report back later.
Re: AC Not Working Reply #13 – July 07, 2022, 03:46:41 pm Quote from: JonS - July 06, 2022, 01:53:40 pmIf it were mine, I would first plug it into good power source from the house electrical and see if it'll start. If it starts at least you know it's not the air conditioner. If it doesn't start, check all the electrical connections in the converter panel especially the A/C breaker and at the A/C connection. All looks good there then go onto the roof and pull the shroud and check connections in the unit's control box. Look at the capacitor connections make sure nothing is burnt. Look at the run capacitor is it swollen does the fan motor run? Has it been a while since it last ran did it act up then? Lastly or first, don't cycle it on or off too quickly. Give it time to equalize pressures before you try to restart. Ok, it would not start on house electrical. Incoming voltage is good @ 122V. I checked all the AC connections in the converter and they are tight. Same symptoms as before. Hums and vibrates like it wants to start. I took the shroud off and nothing jumped out at me. Where is the control box?
Re: AC Not Working Reply #14 – July 07, 2022, 04:52:46 pm I found the control board underneath a sheetmetal cover. I blew everything out with compressed air and inspected it and didn’t see any loose connections, nor see or smell anything burnt. I’m assuming the big silver cylinder is the capacitor? If so, it doesn’t appear to be swollen. I tried starting the unit again with the sheetmetal cover off. The big black canister is getting very hot and the small one next to it is getting cold. Not sure if that’s from the sun beating down on it or something else. The humming seems to be coming from the large black canister.Voltage at my Kill-a-Watt meter plugged into an outlet inside the coach drops from 122 to 115 volts while attempting to start. 1 Likes
Re: AC Not Working Reply #15 – July 07, 2022, 06:19:28 pm Hi Greg; That 'large black canister' is the compressor. The AC voltage drops when the compressor is trying to run because it is drawing current and getting hot doing it. The silver cylinder is the starting (and running) capacitor. Quite likely it is bad. It shifts the phase of one pair of windings from the other pair that aren't shifted, to get the motor to turn. Hi heat can degrade these capacitors and they lose some efficiency. Age will do that also. They aren't very expensive and are easy to replace. That would be the first course of action to take. RonB 1 Likes
Re: AC Not Working Reply #16 – July 07, 2022, 06:59:05 pm Thanks Ron. Would Dometic be the source for the capacitor?
Re: AC Not Working Reply #17 – July 07, 2022, 07:04:04 pm Greg, Type in V-000403 a bunch will pop up even amazon has them. Jody 2 Likes
Re: AC Not Working Reply #18 – July 07, 2022, 07:46:03 pm Dometic if you want to pay too much. Amazon is convenient. make sure the size is the same. Electrical value and physical. It need to fit in the same space. RonB
Re: AC Not Working Reply #19 – July 07, 2022, 08:04:19 pm A word of caution: those big electrolytic capacitors store a LOT of juice, hold it for hours even after power is shut off, and release it instantaneously if the terminals are shorted. That can weld a tool to the contacts... or more important, it can kill a human. Be extremely careful when working with a big cap like that. Standard advice is to wear rubber gloves and keep one hand behind your back. You can safely discharge a large capacitor, using a simple homemade capacitor discharge tool. This bleeds off the voltage at a safe rate through a large resistor. This video has more information. Please be careful when working on these units! 12 Likes
Re: AC Not Working Reply #20 – July 08, 2022, 03:42:26 pm Just wondering, are the fans working? Like if you turn it on just fan mode, is it working? i didn't see any mention about it (maybe missed it) but after you mentioned that some parts are getting cool, maybe the a/c part is working but just not the fans...
Re: AC Not Working Reply #21 – July 08, 2022, 03:57:23 pm No, the fan doesn’t blow either. From the inside, the unit vibrates and hums while trying to start.
Re: AC Not Working Reply #22 – July 08, 2022, 06:00:15 pm interesting!! now I'm not very familiar with our ac units, but kinda sounds to me like it's the fan part that's having issues... not sure what kicks it off though, but hopefully with this info someone could chime in with something else to check further
Re: AC Not Working Reply #23 – July 08, 2022, 06:07:53 pm Snip>> The big black canister is getting very hot and the small one next to it is getting cold......... The humming seems to be coming from the large black canister.Snip>> No, the fan doesn’t blow either. From the inside, the unit vibrates and hums while trying to start. OK. I'm about 90% sure that what you have is a dead fan motor (and by dead I mean not running... it could have a start capacitor on it that could be bad, but I don't remember if those motors have start capacitors... it could also be a bad connection to the fan motor, or the windings could be bad/open), but that is all. I would not try running the unit any more at this time. The two statements above indicate that the compressor is working just fine. (Compressors get hot because they are compressing the gas, ie adding energy to the gas.) You (or a good repair facility) should be able to replace the fan motor relatively easily. Continuing to experiment will just shorten the life of the compressor. I really think this is a fixable problem.Good luck. Ken 1 Likes
Re: AC Not Working Reply #24 – July 08, 2022, 06:30:33 pm Quote from: Ken and Joyce - July 08, 2022, 06:07:53 pmSnip>> The big black canister is getting very hot and the small one next to it is getting cold......... The humming seems to be coming from the large black canister.Snip>> No, the fan doesn’t blow either. From the inside, the unit vibrates and hums while trying to start. OK. I'm about 90% sure that what you have is a dead fan motor (and by dead I mean not running...This should be easy to check - you should have a 'fan only' mode. If that does not work, then start with the fan as the problem. Try to turn the shaft with the unit off - if it is sticky to turn - does not spin easily - then lube has dried out in the bearings. Try a drop of 3-1 oil every place a shaft turns in a bearing, and work it until the shaft loosens.Steve 4 Likes
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