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steves86ta 08-04-2021 10:03 PM

Rear A/C pulling lots of power
 
Hi All,

i am a new to me owner of a 1997 Bounder 35' motorhome (bought it from my parents).

We bought it mainly to do desert trips and ive been trying to troubleshoot the Generator/Intellitec ECC system since i got it. I believe i have identified an issue with the ECC system but this thread is nto about that.

I added some hard start capacitors to the Original Coleman AC units and went today in the heat to test them out. I turned the generator on, started the front AC and let it get running, i then started the rear AC and once the Air Compressor cycled on the draw was so bad it stalled the generator. I had nothing else drawing power and this is the first time this has happened.

I have noticed since i got the unit the rear ac appears to put more of a "load" on the generator when it starts. I dont have access to shorepower at the time.

So today while i was trying to see what is going on, i plugged my volt meter into an outlet and monitored what happens when the rear AC turns on and when the front AC turns on.

Again, this is running the AC's individually because it was stalling the generator today during the heat of the day (107*).

But the Front AC has always sounded "normal" just a click when the compressor turns on and its blowing cold air. the generator doesnt even seem to react to it turning on. Watching my volt meter, the voltage drops from 120 to 98 for a brief second then recovers to 120 ish almost instantly. Here is a youtube video (slowed down to read numbers more clearly)

https://youtu.be/vY9UskiljaI

The rear AC on the other hand definitely seems to put a load on the generator and doesnt seem to just "click" on if that makes sense. Prior to the hard start cap's it wouldnt turn on unless i was very careful about the startup sequence (the ECC problem). When the rear AC turns on the generator dogs down pretty hard then recovers and will run it as long as its the only thing on (during the heat of the day). Reviewing the video, the voltage at the same outlet drops down to 95 volts, then actually takes a bit of time to recover and return to the 120 range. I have a video of that as well.

https://youtu.be/ab4tJjskPOc

Im open to replacing the AC unit - however i want that to be the last step. To me it doesnt make sense that the rear has these issues when the front is the one with a lot more time on it (it was my parents MH so i know the usage history).

i have replaced the start caps, and inspected the wiring and other caps. They do not show any signs of failing. However I am not sure where else to go from here or what else to check to verify that i do need to replace the unit. I will say that when the rear AC is on, it does blow ice cold and will run as long as i have it on. Also - it is not blowing any breakers.

Thank you in advance

gatorcq 08-04-2021 10:12 PM

So, you may have a bad compressor.

Biljol 08-04-2021 10:50 PM

Or a bad cap.

How about trying a soft start instead of a hard cap? I know they are more $ but less than a new ac unit and at 299 with a 90day no questions asked return what do you have to loose?

https://www.softstartrv.com

Btw I do not work for them or have any interest in that co just trying to get you a solution.

Old-Biscuit 08-04-2021 11:01 PM

What size Generator?
What size are the A/C Units?

steves86ta 08-04-2021 11:06 PM

Quote:

Originally Posted by Old-Biscuit (Post 5860869)
What size Generator?
What size are the A/C Units?

Onan 5000

13.5 and a 15k up front

The 13.5k is the one with the issue over the 15k

Biljol 08-05-2021 12:18 AM

That was a good question that genset is rated at 45 amps.

The startup amps on 13500 has been measured at 45 amps so with the front ac pulling 12-15 amps you would not have the head room to start.

You reversed the start up rear first then the front and you are getting the same results. Thatís sounds like there are not the amps needed.

I think there just is not the amps available to start both. That would be where the softstart would come into play.

Even if you got them both to start your going to be low on extra amps for other items like charging the batteryís. My coach pulls 5 amps just sitting with nothing on.

Most people with 2ac units have a 7500 I think. I have a 10k and have had issues running all my power at the same time with 2 acís running. Lucky i swapped my inverter with one that has power assistance.

steves86ta 08-05-2021 09:14 AM

Quote:

Originally Posted by Biljol (Post 5860916)
That was a good question that genset is rated at 45 amps.

The startup amps on 13500 has been measured at 45 amps so with the front ac pulling 12-15 amps you would not have the head room to start.

You reversed the start up rear first then the front and you are getting the same results. Thatís sounds like there are not the amps needed.

I think there just is not the amps available to start both. That would be where the softstart would come into play.

Even if you got them both to start your going to be low on extra amps for other items like charging the batteryís. My coach pulls 5 amps just sitting with nothing on.

Most people with 2ac units have a 7500 I think. I have a 10k and have had issues running all my power at the same time with 2 acís running. Lucky i swapped my inverter with one that has power assistance.

I know for a fact the generator used to run both ac without a problem.

What I'm trying to figure it out is why the rear is pulling so much power to run in comparison to the front.

The voltage tests were done with only the one ac being tested on.

I'm thinking the rear has a bad compressor and it's just time to look for a replacement. But also just trying to verify my diagnosis

Biljol 08-05-2021 08:31 PM

But it ran both before you put in the hard start capsÖ.

Read up on amp draw with hard start caps they actually use more amps for less time than a standard cap (to get a compressor that would not run to run) so your peak amps are higher during starting.

Also in the heat your AC will pull more amps than in milder climates up to 10 amps more in some cases.

MarvinG 08-05-2021 08:38 PM

Actually, no, it wasn’t working before he put in the SPP6, hard starts. A soft start is a great help for a good working air conditioner I agree, but I wouldn’t put a soft start on, or spend the money for it, until I completely fixed the AC to properly work on regular shore or the OEM generator on the Bounder.

Steve, you can’t always tell if the run cap is good by looking at it. If you don’t have a tester, just buy one run capacitor to replace it and install it. That will narrow down whether you have a cranky compressor that is on its way out, or a bad run capacitor.

Biljol 08-05-2021 08:42 PM

Marvin has a good point but I did not see a comment that they were not working before.

I just thought easy way to test the amp draw issue ó- when on shore power do they work?

If they do your pulling to many amps for the genset. If not itís something else.

This assumption is made that your have a 50amp service coach.

MarvinG 08-06-2021 06:37 AM

Right, you had no way of knowing, I chimed in because of another thread where Steve is troubleshooting the Intellitec energy management system. He is on 30 amp service. He definitely appears to have an AC that is having trouble starting and may or may not have an Intellitec problem. I believe it does the same on shore power or generator but he will chime in here and clarify I’m sure. I have the same year and model and also have SPP6 on mine and everything works as it should, so in a sense we have a baseline showing that his should work correctly, once he diagnoses and repairs the issue(s).

Biljol 08-06-2021 08:25 AM

Ok I really wish manufacturers would not do 30 amp if you have 2 ac units it leave so little overhead if both ACís are running.

Especially when 50 amp is a misnomer since itís two legs of 50 amp for a total of 100.

So he actually has more power from the the genset than shore power at 45 amps.

But to clarify is he on 30 amp with a 50 amp coach or is it a 30 amp coach?

I recently was at a campground that had bad 30 amp service and could not run both of my 15k ac units due to low voltage.

sibe 08-06-2021 09:16 AM

Lost of info here back and forth, I commented on other thread, back up a bit..

Do some good amp probe measurements, not only volt drops.. on Each unit on a HOT day after running for a while, turn up temp so it starts to cycle, then watch the amp draw..
NOW, if you have the start up problem when you first run the AC units then...

Verify all wiring is good, tight connections.. breakers are good or fresh, old breakers can not hold amps at times..

You did a hot start and it helped.. did you replace with proper one, I sued an E version with thermo disc etc.. I got another year out of my AC before it started to stall genny and pop breakers again..

New AC and my issues are gone other than a Genny issue that I caused with govener blaming it and not the AC... oops..

If it was be and I am a DIY proclaimed guru, I would get my self some 12/2 romex and temporay run some leads to each AC and remove that EMS from the path.. This way you have it narrowed down if AC is actuall ok or not..

Or pull inside trim off both AC and use that romex wire to run rear off of front feed and reverse.. this can elimate some stuff..

but i think your rear AC weak

Good luck..

MarvinG 08-06-2021 06:35 PM

It is a 30 amp service on the rig. That is the way these older ones came from the factory. Yes, the generator does have more output capacity than shore power. I’m with you, sibe, before I would condemn the AC I would run romex straight to the unit and test to make sure the unit is still drawing too high amperage on startup.


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