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Old 06-22-2018, 05:43 PM   #1
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Brand: Thor Motor Coach
Model: Challenger 37LX
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THOR #6310
Amps and A/C

We have a Challenger with two 13,500 BTU A/C units. It is a challenge to get the inside temp down below 80 degrees when it’s 89 degrees outside. I have read all the threads on improving interior cooling. We put Reflectix in the windshield. Vents are closed. Filters kept clean. We made sure the baffles are in position and taped them in place with foil tape. We have not yet added the extra vent to the cover as some here have done. While I understand it worked to improve the cooling for some folks, I'm having a hard time accepting that fix since I believe we should be able to do better than we are with two 13,500 BTU units.

With both A/C units running, we noticed that one leg of the 240V 50A service is pulling 34 amps and the other less than an amp. Why would both A/C units be wired to the same leg? Would this possibly cause the A/C unit to be less efficient?

Just trying to run down all possibilities before we replace the front unit with a 15,000 BTU.
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Old 06-22-2018, 06:29 PM   #2
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It should be fixed whether itís impacting a/c performance or not. Thorís wiring is not larger gauge than minimally required for the expected load. Until it is sorted out, you might want to check for warm wires as well as the ac voltage at one of the air conditioners with both running. My opinion, anyway.
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Old 06-22-2018, 06:38 PM   #3
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with 50amps on each leg, it probably matters little 'which' side each A/C is attached to, as it's plenty of amps for the A/C requirements, each only 12amps or so. You may just not be using any of the other items on the other 'leg', such as the Water Heater(elec element), and the Inverted circuits(sub panel), such as the many outlets in the coach, including TVs, Fridge, Microwave, etc.
If the TVs are off, the microwave is not in use, and the Fridge's compressor is not running, you could have most of your current usage only on one leg of the breaker box.

I don't want to say that you don't deserve what you think the A/C units should be giving you, but I also know that everyone has a different 'feel' for what 'temperature' is to them. I may can take 80 degrees and think it's great, you may not. We use a LOT of fans around the coach, to keep the air moving, which is more important to me than simply the temperature that the thermostat is reading.

The outside temp, humidity, your insulation of the coach, whether you are under shade, etc., all impact the feeling of being comfortable.
Even our own spouses usually have a difference of opinion of whether it's comfortable or not!

To each his/her own : )

I've also found on our two 13.5k units, probably just like yours, is to OPEN the full force outlet, rather than using the round vents... it will still come out the vents, but will be more forceful right under the units.
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Old 06-22-2018, 07:00 PM   #4
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Originally Posted by BradnKaren View Post

.....cut.... Would this possibly cause the A/C unit to be less efficient?

Just trying to run down all possibilities before we replace the front unit with a 15,000 BTU.

In practice, no, not enough effect on cooling capacity to measure. You could make a better case for electrical efficiency, but that too is pointless unless there is more you didnít mention.


If you get to point of replacing front A/C, since youíd be buying a new one anyway, you may want to ask if they can add it as a third A/C instead. It may not be doable on your MH, but if possible and can be powered from other leg, you would get a lot more cooling than the extra 1,500 BTU/hr. Granted, if itís even possible the cost would be higher for sure, but maybe worth it if you like it cold. Just another option to ask about.
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Old 06-22-2018, 07:40 PM   #5
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I don't think I'm asking for too much in expecting better than a 10 degree difference between indoor and outdoor temps. What do peeps in REALLY hot climates like AZ do?

Before this RV we had a 37ft 30 amp coach (2002 Southwind) with two 13,500 BTU A/C units that got as cold as an icebox in the exact same spot and weather conditions we're in right now.

Breakers and wires are cool. Air from the vents is flowing well. We have tried various combinations of open/closed/re-positioned A/C and ceiling vents without much difference in overall temp.

It may just boil down to crappy insulation.
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Old 06-22-2018, 08:01 PM   #6
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Yeah, new units tend to be larger, have thinner walls, aluminum framing, larger windows for greater natural light, and more/larger slides. It all adds up in my opinion. It's sometimes hard to compare directly.
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Old 06-22-2018, 08:09 PM   #7
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Yep, I guess the only thing you can do is measure the volume (hard) and the temperature directly out of vents (easy). I know that many have made shades for windows, but has anyone taken the investment of this product on their windows. It is UNBELIEVABLE in my wife's car- feel no heat thru the windows at all.

Ceramic film is the highest quality of window tint film, and also the most expensive, contains neither metal, dye, nor carbon, but instead a kind of ceramic particle that is both nonconductive and nonmetallic. Ceramic film has only recently appeared on the market, but has already proven its worth in terms of performance and reliability. Ceramic window-tinting film cuts from 45% to 50% of the solar heat that enters through the windows in the form of infrared light, while allowing maximum visibility both by day and night. Like carbon film, ceramic window-tinting film allows maximum efficiency in the functioning of radios, cell phones, GPS systems, and all other such devices being operated from inside the protected space. It surpasses the other types in its resistance to glare and fading, and renders windows highly shatter-proof. Ceramic film is also most effective in its blocking of ultraviolet light from the interior; in the case of ultraviolet light (the kind of light rays that contribute to sunburn and skin cancer), ceramic window-tinting film can block up to 99% from entering the interior.
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Old 06-22-2018, 08:20 PM   #8
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Can you get this ceramic at (almost...) any window-tinting place?
Or is it more specialized than that?
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Old 06-22-2018, 08:28 PM   #9
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No , you can get it almost anywhere nowadays. My guess is 2-3k to do an RV- my buddy dropped 4k for his boat.
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Old 06-22-2018, 08:33 PM   #10
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Thanks for the information: this deserves a bit of closer scrutiny!
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Old 06-22-2018, 09:08 PM   #11
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Fist of all get a good digital thermometer or borrow one for an A/C repair place. Check the temp of the air going in after the A/C has been on high cool for at least 10 minutes. Doesn't matter what the humidity or the ambient air temps is. Don't use the thermometer on the dash or on the thermostat. Now check the temp of the air coming out of the A/C; not the temp of the housing or the temperature coming out of the ceiling ducts. The difference in the air temperatures of the inlet and outlet should be 20 degrees plus or minus 3 degrees. If it is not you air conditioner needs to be serviced by cleaning the filters, cleaning the condenser and/or cleaning the evaporator. The A/C units have a sealed refrigerant system which seldom fails. Most of the cooling problems are caused by dirt, dust and hair clogging the system. There have been cases when the baffle between the air entering evaporator and exiting the evaporator is bent or misplaced. Each A/C is a separate unit they should be check separately.
A/C current draw will vary with the compressor loads (ambient temperature). Typical draw for a 15,000 btu A/C on a 95 F ambient 80% humidity day is 17 amps, for a 13,500 btu unit about 15 amps, for a Mach 3PS about 11 amps. and for a Polar Cub (my favorite) 9 amps.
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Old 06-22-2018, 09:17 PM   #12
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Quote:
Originally Posted by BradnKaren View Post
I don't think I'm asking for too much in expecting better than a 10 degree difference between indoor and outdoor temps. What do peeps in REALLY hot climates like AZ do?

Before this RV we had a 37ft 30 amp coach (2002 Southwind) with two 13,500 BTU A/C units that got as cold as an icebox in the exact same spot and weather conditions we're in right now.

Breakers and wires are cool. Air from the vents is flowing well. We have tried various combinations of open/closed/re-positioned A/C and ceiling vents without much difference in overall temp.

It may just boil down to crappy insulation.
Dont forget to consider that your new coach has full body paint in a dark color and Big, dark windows, where your old one may not. Items to make your own shade may be something to look at.
I found that the "automatic" thermostat system doesnt work that well. I find when it is real hot it works better when I use the fan on high setting.
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Old 06-22-2018, 11:22 PM   #13
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The factory duct system is very restrictive and even with the quick cool vents open the air still has to make a 90 degree turn to go anywhere. The add on circular vents work because they are directly under the exhaust and move more air, plus you have the added benefit of being able to direct the air where you want it.
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Old 06-23-2018, 12:20 AM   #14
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Super...
Do you know of any videos, that showcase the installation of those vents?
(I do my best learning; when I can see the process.)
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Old 06-23-2018, 12:21 AM   #15
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Quote:
Originally Posted by Beau388 View Post
Fist of all get a good digital thermometer or borrow one for an A/C repair place. Check the temp of the air going in after the A/C has been on high cool for at least 10 minutes. Doesn't matter what the humidity or the ambient air temps is. Don't use the thermometer on the dash or on the thermostat. Now check the temp of the air coming out of the A/C; not the temp of the housing or the temperature coming out of the ceiling ducts. The difference in the air temperatures of the inlet and outlet should be 20 degrees plus or minus 3 degrees. If it is not you air conditioner needs to be serviced by cleaning the filters, cleaning the condenser and/or cleaning the evaporator. The A/C units have a sealed refrigerant system which seldom fails. Most of the cooling problems are caused by dirt, dust and hair clogging the system. There have been cases when the baffle between the air entering evaporator and exiting the evaporator is bent or misplaced. Each A/C is a separate unit they should be check separately.
A/C current draw will vary with the compressor loads (ambient temperature). Typical draw for a 15,000 btu A/C on a 95 F ambient 80% humidity day is 17 amps, for a 13,500 btu unit about 15 amps, for a Mach 3PS about 11 amps. and for a Polar Cub (my favorite) 9 amps.
Jim is correct. Check your temps going in and coming out of the unit. If 20* or so then you know its working properly and you have other problems like insulation etc


Good luck

Jerry
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Old 06-23-2018, 12:36 AM   #16
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Quote:
Originally Posted by Bob Denman View Post
Super...
Do you know of any videos, that showcase the installation of those vents?
(I do my best learning; when I can see the process.)
Sorry, no. Iíve done several of these vents but never made a video, mostly because I donít have a video cam, and secondly I donít know how.
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Old 06-23-2018, 07:46 PM   #17
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I live in Arizona and had the same problem with cooling. I have a 2018 35M Hurricane with two 13,500 AC units and could not get the coach to cool down. I had a crazy thought one day and bought a room divider ceiling track online and installed it directly behind the front seats. I got a pair of room darkening insulated drapes t Wally World and push them to each side when traveling. When stopped we pull them together and hold them with chip clips and wala, better cooling instantly. I'm not saying this is the cure but it sure helped in the 110-120 degree days and if you stick your head through the curtains the driver's compartment is too hot to breathe in. Stands to reason that if you have less space to cool the AC will work better. I'm just speaking from personal experience but it works well for me.
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Old 06-24-2018, 05:53 PM   #18
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Is there any way to hang a couple of small cooling fans up in your "slightly-cracked" coach windows? That would help to keep the temperatures up these a bit less unreasonable...
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