2004 Adventurer/W22 Basement A/C

CMcCardell · 09-05-2009, 09:13 PM

I'm in over my head when it comes to electrical systems, but here's my problem:

The basement air in my 35U was on today, outside temp just under 90, and it could only keep the interior at 83. Something's not right. So I checked the return air, cleaned the outside fins (they weren't dirty) and noted that the system was pulling about 10-ish amps with the fan/AC on. I'm assuming only one compressor was working.

The coach is hooked up on a 30A service via the factory cord plus 75' extension. The service tripped once but has been fine since, though I've never seen the coach pull more than 18-20. The power panel is set to 30A service and the water heater, comp # 2, etc are lit.

If I start the generator, the coach draw heads near 20 (I'm assuming that compressor #2 kicks on), the temperature starts dropping, and the a/c system works fine.

So my assumption is that the a/c system is fine, comps 1 & 2 both work, but only one will work off 30A service after the generator is shut down. Why? The panel's only showing a max 20A draw, with all accessories supplied power. But the breaker blew once at about that draw (fine since). We're not close to 30A so why is comp # 2 not coming on?

Any hints on where to go from here?

Thanks in advance,

- Clay

Jerry Kraft · 09-05-2009, 09:34 PM

Hi Clay, there is a selector button at that panel that says 20amp or 30amp Is the 30 amp selected. You just push it in to select. Hope that is it. Regards, Jerry Kraft

CMcCardell · 09-06-2009, 08:09 AM

Hi Jerry -

Yes, 30A is selected -

- Clay

jdsr · 09-06-2009, 12:50 PM

I dont believe you ext cord will handle the amp draw of the second comp cutting in. Maybe thats why it wont work on ext cord but will otherwise. Try plugging in without ext cord if poss.

Dunnpe · 09-06-2009, 10:03 PM

jdsr hit it on the head. Unless you have an extension cord that has wires rated to carry a 30A draw you aren't getting that amount of amps to your coach. If I use a 12ga wire approx 75 long can't get the amps needed to go throught it. I use a 10awg approx 75 foot long ext. cord and it handles the 30 amp easily.

CMcCardell · 09-08-2009, 09:29 AM

Thanks folks -

That makes sense, I suppose, but - how does Comp #2 know not to come on because of the extension cord limitation, when the panel is set to 30A?

- Clay

jdsr · 09-08-2009, 10:22 AM

Quote:

Originally Posted by CMcCardell

Thanks folks -

That makes sense, I suppose, but - how does Comp #2 know not to come on because of the extension cord limitation, when the panel is set to 30A?

- Clay

What Im thinking is it trys to come on but the cord wont allow that much amp draw. Its takes more amps for startup then running amps.This might not be your problem at all but to find out plug mh into outlet without ext cord and see if it works if poss. My guess with it working on the generator the cord might be the problem. You can call rvp. Those guys IMO are great to work with on their units.

Jerry Kraft · 09-08-2009, 11:06 AM

Hi Clay, I have to go along with the fact that your total length of extension cord is just too long. There is an electrical term called voltage drop. That happens when the conducting wire gets very long. Voltage drop is also afected by the size of the conductor, the smaller the wire the more the voltage drops. There is a formula, but I don't remember what it is. I am a retired electrician, but that was almost 20 years ago. In the length that you are using, instead of 120volts it could drop to as little as 100volts. That may be enough to start compressor # 1, but too little voltage for both compressors. I really think you should find a way to connect directly using only the cord that is wired into your rig. Regards, Jerry Kraft

CMcCardell · 09-08-2009, 12:29 PM

Thanks all - I appreciate the input/advice! At least (for a change) it's not something with the coach itself, in a likelihood -

Unfortunately the power isn't close enough to where I can feasibly park the coach - it's probably not a big deal as we're over the hot part of the year here in Wyoming, but I need to get an electrician to do some work around here at some point and I'll see what he says.

Thanks again!

- Clay

bruceh · 09-09-2009, 10:40 AM

I always keep one of those cheap CW voltmeters plugged into an AC outlet. I am betting that it would show low voltage in your case.

Dunnpe · 09-10-2009, 03:59 PM

Clay, if you Google " Extension Cord voltage drop you will find "Approximate voltage drop in extension cord gages" a pdf file that has a chart that explains the drop in layman terms
Hope this helps

CMcCardell · 09-11-2009, 10:34 AM

Quote:

Originally Posted by Dunnpe

Clay, if you Google " Extension Cord voltage drop you will find "Approximate voltage drop in extension cord gages" a pdf file that has a chart that explains the drop in layman terms
Hope this helps

Great tip, Peter - much appreciated!

- Clay