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Old 07-12-2010, 11:02 AM   #15
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If you have any choice of sites, try to pick one that faces east...The front of the trailer will see full sun in the morning when it's cooler, the back will get the sun during the hot part of the evening. Since the rear AC has some extra capacity this is your best bet. The worst orientation is north/south with no awnings extended since the sides are completely exposed to solar.

My 34' managed to stay upper 70's/low 80's in the front during our last outing to the Gulf...by 11:00 the outside thermometer showed 114 degrees in the sun. The 13.5k btu front ran all day but the 11.0k btu rear would cycle.
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Old 07-12-2010, 12:56 PM   #16
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Jammer,

Do a temp test after the units have been running for 15 minutes. Check the exhaust (cold) air, then the return air at the unit. You should get a 18-22* differential. If not, you might be low on refrigerant, which usually means a new roof unit, as these are sealed at the factory and have NO process valves on them. You also might be under warranty for this problem (3 year Dometic warranty).

If you find that you are not getting the temp differential within range, do an amp draw test at the compressor of the offending unit. Put an amp clamp around the black wire going to the compressor, then the white wire (under the shroud). You should be getting close to the rated amp draw on the label on the unit, depending on the outside ambient temperature.

If not, and it is markedly lower, you definitely have a loss of refrigerant.

Also, you might try these: RV Sunshade Co.

I have been using them for 10 years, first on my 40' diesel MoHo, then on every window on the 19CCD, and again on every window on my '96 Beaver Patriot. Definitely keeps you cooler and still lets you see out during the day, while not allowing you to see in......great product!
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Old 07-12-2010, 01:24 PM   #17
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Lew,

I'll try that. The temperature differential is definitely less than 18 degrees. I suspect based on the other posts here though that there is exterior air leakage into the shroud around the evaporator. The unit is new this year and should still be under warranty should there be a refrigerant leak.
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Old 07-12-2010, 05:11 PM   #18
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Quote:
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...The unit is new this year and should still be under warranty should there be a refrigerant leak.
purchased in march/april my units FIRST real a/c use showed 'diminished performance' not unlike YOUR report ...

"normal" was the tech diagnosis.

that july (4 months from new) the a/c crapped out with a FULL blow coolant leak on a 95+ day.

i suspect a small leak had been present earlier.
_________

so the ac was then replaced 3 times (a drama/saga and pia) before they finally got it right...
_________

IF your unit needs replacement under warranty TRY getting them to up grade it to 15,000 btu...

same power requirements as the 13.5 but bigger fins and cooling unit account for the extra capacity.

cheers
2air'
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Old 07-12-2010, 05:28 PM   #19
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Well, at least I have two of them.
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Old 07-12-2010, 07:01 PM   #20
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If its still under warranty let the dealer take care of your problem. It sounds like your front unit isnt putting out what it should and they just might replace it for you.
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Old 07-12-2010, 07:17 PM   #21
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Quote:
Originally Posted by Jammer View Post
Lew,

I'll try that. The temperature differential is definitely less than 18 degrees. I suspect based on the other posts here though that there is exterior air leakage into the shroud around the evaporator. The unit is new this year and should still be under warranty should there be a refrigerant leak.
That temp differential should be the same regardless of the outside ambient temps since it measures the performance of the unit from the inside of the coach, so less that 18* is a definite problem!

Another 'trick' that I use is to use heavy aluminum tape around all of the seams on the evaporator cover and be sure that the 2 or 3 openings in that inner shroud are completely sealed.

Another problem on the newer Duo-Therm units is improper foam sealing. This 2 X 2" strip of foam usually runs along the top of the condenser coils, across the top rear of the evaporator shroud, down the right side along the rear edge of the control box and also along the rear seam of the condenser from the top left to the base pan. This foam is really important for proper cooling efficiency in the Duo-Therm units. If you don't see it on top of teh coils, it might be stuck to the inner top of the A/C shroud.

If you have one of the newer units that have a molded plastic evaporator shroud, you might check to see that all of the screws are in place and that the friction clasps (IIRC, there are about 6-7 of these spaced around the seam of the shroud) are properly snapped down. These newer covers are much better than the older ones, but only if they are properly installed....... and I have seen some that were NOT !!
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Old 07-12-2010, 07:50 PM   #22
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Unfortunately without a tap on the suction line it is hard to determine the super heat. What you can do is remove the shroud and check for any outside air infiltration. If the that is OK and after the unit has run for at least 15 min. look at the suction line, the larger of the 2 at the compressor. Pull back the insulation. The pipe should be wet if there is any level of humidity. If it is dry or shows ice close to the compressor you are low on gas and need a replacement.
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Old 06-03-2014, 03:22 PM   #23
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New twist on an old problem.

As I have posted elsewhere, my trailer went to the dealer on several occasions for warranty work. A/C problems were on the "punch list" on most of these visits, and I did find and resolve some A/C-related problems myself. The dealer fixed a vibration problem in the rear A/C, and I found and fixed a wiring problem in the temperature sensor for the rear A/C. Ultimately, the dealer declared that there was nothing wrong with the front A/C and it was cooling sufficiently. By then it was fall and I quit pursuing the matter.

With both A/Cs operating, the trailer cools marginally, as I have reported in other threads. Performance is unchanged since the unit was new.

I have been up on the roof and have opened up both A/C shrouds. The front A/C is the "high capacity" model, 15,000 btu/h. The rear one is 13,500 btu/h. These were among the first R-410a Penguins made. They are the heat pump model. There are no problems with blockage or missing foam, etc.

I recently took an accurate measurement of amp draw and voltage, which showed that the front A/C is drawing less current than it should. I rechecked the temperature differential, which is around 15 degrees on the front A/C and 25 degrees on the rear A/C.

I've decided to try again to get the front A/C fixed and am taking the trailer to a different Dometic service center. I anticipate that there will be a spirited discussion over whether this repair is covered by warranty.
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Old 06-03-2014, 03:35 PM   #24
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Not sure what refrigerant is in your unit but when I was working with ACs in an earlier life time 18 to 20 degrees was consider the limit in efficiency for a unit. Given the 15 degree differential on the front unit I would say it could use some help.

I would request that who ever looks at the unit test the superheat on it. That is where the rubber meet the road and can't be faked.
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Old 06-17-2014, 09:58 AM   #25
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Some measurements I took that may be helpful to others.

118v supply voltage under load.
88 degrees F. ambient temperature. Windows open, same temp in and out.

Rear A/C appears to be working properly. 13,500 BTU Dometic Penguin with R-410a:
Low fan 2.8a
High fan 3.4a (nameplate 3.5a)
High cool 10.0a (compressor only) (nameplate RLA 12.5)
Outlet temperature 64 degrees, 24 degrees below inlet

Front A/C (insufficient cooling). Dometic "high capacity," also R-410a.
Low fan 2.3a
High fan 2.7a
High cool (compressor only) 7.8a
Outlet temperature 74 degrees, 14 degrees below inlet.

Readings were taken one unit at a time after each unit had been operated for several minutes to allow it to stabilize.

I didn't photograph the front unit's nameplate so I'm unsure of its ratings. Dometic's web site shows 13.4 RLA for the compressor and 2.6 for the fan, but I know that there can be some variation depending on production date.

The trailer is at a Dometic service center now and I'm trying to get Dometic to cover repairs or replacement under warranty.
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Old 06-17-2014, 10:14 AM   #26
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Assuming that there is sufficient refrigerant in the unit, my guess is that the heat pump valve is leaking internally.

This makes everything fit including the front units lower current draw.
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Old 06-17-2014, 10:19 AM   #27
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And since the manufacturer doesn't see fit to manufacture a unit that is really repairable I would say that with your record of service history......

Well
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Old 06-17-2014, 11:04 AM   #28
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We've used that insulated reflective roll material, cut to fit between the windows and screens, and in skylights and fan tas tic fans (in the interior) and found 105 full sun bearAble in full AZ sun, with our 30' classic, one ac unit. Our blessing was the very low humidity.
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