Chezyrider Report post Posted June 19, 2018 Has anyone tried running a portable air conditioner off of your inverter will driving to help out the dash air in a Class A motor home? After a few hours of driving in 90+ degree weather, it’s like an easy bake oven. Have tried running the generator with the roof air on, but the ducts are block by my slides being pulled in. Installed a thermal curtain behind the front seats, but only helps for a short time. I was thinking that a little 8,000 BTU 115 volt portable A/C set between the front seats in front of my curtain. Then send the exhaust duct to the back of the coach since it’s going to be hot anyway. Would the inverter be able to handle the residential refrigerator, plus the portable air condition while driving? Share this post Link to post Share on other sites
wolfe10 Report post Posted June 19, 2018 Chezrider, Welcome to the FMCA Forum. Please tell us what motorhome you have. What chassis/alternator you have-- that will determine if the engine-driven alternator can keep up with the electrical draw? What inverter or inverter charger do you have-- is it MSW or PSW? I know that is a lot of questions, but without the FACTS, all we can do is speculate. Share this post Link to post Share on other sites
richard5933 Report post Posted June 19, 2018 Welcome to the forum. Did your dash a/c ever keep you comfortable or is this a new situation? Share this post Link to post Share on other sites
kaypsmith Report post Posted June 20, 2018 To run an 8 seer 8000 btu AC unit, you will need to figure 1000 watts just to run it, that's 8.5 amps, you will need about 1500 watts for the starting load, about 12 amps. The exhaust into the rear portion of the coach is not a good idea because of the heat plus humidity factor, yes there is a collector for the evaporator condensation, but the heat alone causes additional moisture after the evaporator. You could vent it to a roof vent or to a side window. The above figures will help in the equation for what Brett has asked for. Yes I have a portable AC unit that I have used in the coach, but I am not hampered with the slide restriction, so I usually just turn on the roof air and use a portable fan to direct the air flow to the front of the coach. On the last trip I actually used one of those portable coolers that is advertised on TV, it helped a whole lot. Share this post Link to post Share on other sites
hermanmullins Report post Posted June 20, 2018 Chezyrider, Welcome to the Forum. If you dash A/C cool well but wont do so good in really hot weather try putting up a curtain of some sort behind the Drivers and passengers seats. We use one all the time and it help by not trying to cool the entire coach with just the dash air. May I ask, rather then trying to put in a heavy portable A/C, why don't you just run your generator and roof A/C? Herman Share this post Link to post Share on other sites
kaypsmith Report post Posted June 20, 2018 12 hours ago, Chezyrider said: Have tried running the generator with the roof air on, but the ducts are block by my slides being pulled in. Installed a thermal curtain behind the front seats, but only helps for a short time. Hummm!!! Question already answered in the OP. Share this post Link to post Share on other sites
rsbilledwards Report post Posted June 20, 2018 It is an "old" guy thing happens all the time. Share this post Link to post Share on other sites
Chezyrider Report post Posted June 20, 2018 I have a 2012 Tiffin Phaeton 42LH on a Spartan Chassis with a Cummins ISL9 diesel. Couldn’t find any alternator info. The inverter/charger is a Magnum 2800W Pure Sine Wave with continuous power of 23A, and a 5 second surge power of 32.5 amps. Model #MS31884. I also have 6 new AGM deep cycle batteries. The portable air conditioner I’m considering draws 9.04A or 1,040 Watts/hr. I could always run this A/C off of my generation while driving, but was just wondering if running it off of the inverter was a feasible idea. FYI I just talked to an technical support agent at Magnum Energy, and they say on paper, it’s feasible, but in the practical sense, not recommended. Thank’s for y’all’s input. Chezyrider Share this post Link to post Share on other sites
wolfe10 Report post Posted June 20, 2018 I agree, not practical from load on alternator/coach electrical system OR additional heat to interior. I would look at making a diverter to move roof air forward and use the generator to power it. Share this post Link to post Share on other sites
kaypsmith Report post Posted June 20, 2018 29 minutes ago, wolfe10 said: I would look at making a diverter to move roof air forward and use the generator to power it. 100% agree, I'm sure that yours is a ducted system, should be pretty simple to make or have made an extension to your system. Share this post Link to post Share on other sites
wayne77590 Report post Posted June 20, 2018 I would definitely make a cardboard or tin contraption with a hole in it to put in one of the smaller windows to vent out the humidity. Share this post Link to post Share on other sites
wolfe10 Report post Posted June 20, 2018 Wayne, So, you are suggesting that the portable A/C is a reasonable option if he ducts the exhaust outside? Kind of thinking out loud here: Wonder how many CFM of outside (hot and humid) air would have to enter the coach to allow for that amount of exhaust? Wonder if that would cause enough negative pressure in the coach to draw in fumes from gray/black tanks? Share this post Link to post Share on other sites
richard5933 Report post Posted June 20, 2018 Is the assumption here that the dash air is working properly but just not up to the task at hand? Shouldn't take much to have the system checked out to confirm that the system is holding pressure and doing what it should be doing. If it needs repair, that would be my first choice. Probably a much better long-term solution just to get things working properly if they are not currently doing so. I'm in the process of having the compressor changed out on our OTR (over-the-road) a/c unit - it was leaking and not able to cool anymore. There is nothing that I could rig up that will ever cool as well as my OTR a/c can when it's working properly. Share this post Link to post Share on other sites
wayne77590 Report post Posted June 20, 2018 Brett, I'm not saying it is a reasonable option to have a portable AC but if one must a vent going to the outside would be better than letting it vent into the RV. Cracking any other window a fraction of an inch would prevent the negative pressure. In my RV the dash air keeps us cool and for the last 3 weeks we have been traveling in 90˚+ temperatures. When we stop for fuel and I walk to the rear of the coach it is very warm and humid so the humidity is in the coach. A portable unit would just suck that in and spit it back into the coach so If I HAD to go the route of a portable unit I would try and duct it to the outside. If the dash AC in his unit is not keeping the front seats cool enough it really needs to be tested. With the curtain described it should keep the front seat occupants cool. I use a thermometer in one of my vents and can monitor the air temp coming out. It's only 55 degrees with that stem thermometer but with the IR it is about 45-50. Cool enough to keep us cool. The diverter mentioned would be the simplest way. A cardboard box trimmed to fit under the vent and the other end past the slide with an open hole should do the trick. I would sure try that way before spending the money and energy on a portable unit. Share this post Link to post Share on other sites
kaypsmith Report post Posted June 20, 2018 The portable AC's (not a window unit) have a venting system which includes a Hose/pipe that is designed to be fitted to an exhaust vent, they actually come with this type contraption that will fit a window opening. If you used an 8000 btu portable unit, it will cool 8000 on the front side, but will also exhaust 8000 hot air out the exhaust. Share this post Link to post Share on other sites
wolfe10 Report post Posted June 20, 2018 Not suggesting it couldn't be done. BUT, were it mine here is what I would do before spending $$ on "may work" solutions that would put additional strain on the coach's 12 VDC electrical system: Build a "duct" that could be temporarily fit to the roof air to direct air forward while slide in/driving. If that did not give enough air flow, use a small fan on the floor blowing the cool air forward. Use together if needed. Share this post Link to post Share on other sites
Chezyrider Report post Posted June 20, 2018 My dash air works fine. I had a new compressor installed 2 years ago. Dash vents blow pretty icy cold air, but on a sunny day 95+ degree day, even with the sun shades partially down, and a curtain drawn behind us, it eventually is overwhelm by all of the front glass acting magnifying glass. It probably doesn’t help that our Golden Retriever hogs a couple of the vents. I think I’ll try a diverter, but the portable A/C does come with a window kit for the exhaust that’ll make a clean application in a side sliding window. Thanks for the ideas. Chezyrider Share this post Link to post Share on other sites
wayne77590 Report post Posted June 20, 2018 Our Husky always closes two of the dash vents when she bellies up to the window. A diverter duct is really the better of the solutions. Share this post Link to post Share on other sites
erniee Report post Posted June 20, 2018 does your roof air have a diverter in the return air to make cold air come down instead of to the ducts? Share this post Link to post Share on other sites
