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04-24-2008, 12:51 PM
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#1
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Senior Member
Join Date: Feb 2005
Location: everywhere
Posts: 527
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The compressor in our front air conditioner freezes up when it runs a lot. We were told that when it's humid we need to keep the fan running all the time, but now we are in Arizona where nobody's ever heard of humidity and it still freezes up. Is this normal? Has anyone else experienced this? We can leave the fan on all the time but we enjoy the occasional quiet.
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Jerry & Shirley Friedman
2014 Chevy Silverado 3500HD
2015 Mobile Suites 38RSSB3
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04-24-2008, 12:51 PM
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#2
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Senior Member
Join Date: Feb 2005
Location: everywhere
Posts: 527
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The compressor in our front air conditioner freezes up when it runs a lot. We were told that when it's humid we need to keep the fan running all the time, but now we are in Arizona where nobody's ever heard of humidity and it still freezes up. Is this normal? Has anyone else experienced this? We can leave the fan on all the time but we enjoy the occasional quiet.
__________________
Jerry & Shirley Friedman
2014 Chevy Silverado 3500HD
2015 Mobile Suites 38RSSB3
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04-24-2008, 01:38 PM
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#3
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Senior Member
Join Date: May 2004
Location: cayucos, ca
Posts: 1,299
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I assume you mean the evaporator coil is freezing up. There is always some moisture in the air and the evap coil will attract it. That is part of the job of an A/C unit. However, that said, the coil should not be freezing up. If the unit has sufficient air form the inside of the coach flowing accross and thru the coil there is no way it should freeze up. So from here, without being there, I would say that you have insuficient air being blown accross the coil. The most obvious trouble spot is the air filter located in the ceiling. Check that. If its plugged clean it.
The other possibility is that the fan motor is blowing to little air accross the coil. Check to see if it is. And now having said all that I realize that to know that the coil was frozen over you would already have had the filter out.
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Ross Starkenburg
2017 Newmar Dutch Star 4369. Spartan chassis w/full disc brakes. 2015 Jeep Grand Cherokee toad
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04-24-2008, 03:40 PM
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#4
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Senior Member
Join Date: Jul 2005
Posts: 214
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If the unit is low on refrigerant, that may be another possible cause for the evaporator to freeze up.
Also, a dirty evaporator or condensor may also cause this problem.
BTF
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04-24-2008, 05:00 PM
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#5
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Moderator Emeritus
Ford Super Duty Owner
Join Date: Aug 2000
Location: Bryan, TX when not traveling.
Posts: 22,945
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90% plus the problem on an RV A/C is low air flow. Low air flow comes from :
-dirty filter
-dirty coil
-using low fan speed
-bypassing air from fan inlet to outlet in the plenum.
The refrigerant system is a sealed (hermetic) design and typically does not leak unless you break a line.
The evaporator coil is the one located indoors and produces the cold air. The condenser coil is on the roof and rejects the heat. A plugged condenser will not cause an evaporator to freeze.
Ken
__________________
Amateur Radio Operator (KE5DFR)|No Longer Full-Time! - 2023 Cougar 22MLS toted by 2022 F150, 3.5L EcoBoost Tow Max FX4 Lariat Travel with one Standard Schnauzer and one small Timneh African Gray Parrot, retired mechanical engineer
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04-24-2008, 09:11 PM
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#6
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Senior Member
Join Date: May 2004
Location: Auburn, CA, Havasu, AZ & Mulege, BCS
Posts: 5,385
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Dusty & Cricket- I'm betting on air bypassing the cooling coil on the coach side. That's not the only possible cause of freezing, but it is most likely IMO given the year of your coach & manufacturing proclivities of the era. On our 06 both AC's has serious open holes between the return air path and the fan/duct assembly. If you remove the plastic grille (which you might as well since its coming off by you or by a service tech), you will be looking at the bottom of the "supply" duct that takes air from around the cold coil and directs it forward and rearward. It is a hollow metal duct in the shape of an upside down tee. ABove the tee in the AC unit is a squirlcage fan that makes the pressure differential to pull air thru the cold coils and push it thru the tee.
The bottom surface of the tee should be a rectangular piece of sheetmetal, maybe w/a thin facing of foam, and 6 or so sheet metal screws. Take that plate off to see up into the supply duct tee; you should see a portion of the squirrel cage fan above, and the mating of the bottom of the AC unit to the tee.
If the top of the tee isn't sealed to the coil box above, the fan will push cold air out into the return air path, and that cold air recirculates up into the coil area again. Freshly refrigerated air circulating immediately back into the coil can cause excessive cold surrounding the coil & freezing. The other common leak is where the fore and aft legs of the tee point ahead & behind to send air to the round supply duct registers in the ceiling. If those two ends are not sealed to the fore and aft duct due to too fast assembly (which was the case on our 06), again, cold air leaks back into the return air path & goes directly back to the cold coil to assist freezing up.
Put your hand up in the tee and see if the metal fins (4) from the upper unit are sealed with tape to the inside top of the tee. If not some aluminum tape from Home Depot or Lowes will do the trick. You can run the AC in this condition, and feel up around past the bottom of the tee into the return air path. If you feel cold air, that's the culprit, or at lease contributing. Do the sealing. Hint: Use many short pieces and overlap them, rather than long pieces. Elegance doesn't count but sealing fully does. Next, feel in the top part of the return air path forward to the front upper edge of the tee. If you feel cold air returning there, the tee isn't properly sealed to the forward duct. Seal that w/the tape. Repeat w/the reaward edges of the tee.
Let us know how this is reconciled. The other common problems causing freezing are less likely, and this is easy DIY stuff. Hope this helps.
__________________
Baja-tested '08 2-slide 36'
Alpine: The Ultimate DIY'er Project
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04-25-2008, 02:31 PM
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#7
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Senior Member
Alpine Owners Club
Join Date: Dec 2001
Location: Las Vegas, NV
Posts: 1,100
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Mike,
I hate to tell you, but the problem is not just in the 2005 and later models. I found the same problem in our 2002 and again in the 2007. I have posted about the air flow issues in the AC, heating and entertainment systems many times, as I feel it is important to check and solve these problems for efficient operation.
Dale
__________________
Dale Gerstel
AMG GTS
Las Vegas, NV
Had: 2007 Limited SE 40fdts
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04-25-2008, 04:45 PM
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#8
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Senior Member
Alpine Owners Club Newmar Owners Club
Join Date: Oct 2005
Location: Fremont, Ca
Posts: 1,325
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I hate this forum! Every time someone has a problem and someone has a good solution I run out to my coach to see if I have the problem (even if I have no symptoms).
I love this forum!!
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Jerry & Judy, Fremont, California
2017 Dutch Star 4018
Freightliner, HWH Active Air
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04-25-2008, 05:33 PM
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#9
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Moderator Emeritus
Ford Super Duty Owner
Join Date: Aug 2000
Location: Bryan, TX when not traveling.
Posts: 22,945
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Seems the manufacturers are getting really sloppy in building the units. We installed a new Dometic A/C in our trailer last year and the first thing I had to do was seal up all of the interior seams to get it to work right. Several air leaks and just plain sloppy assembly.
I have been in the industrial refrigeration field with some work into A/C fro about 39 years now and it is pretty much the same problems, but they seem to be more frequent.
Ken
__________________
Amateur Radio Operator (KE5DFR)|No Longer Full-Time! - 2023 Cougar 22MLS toted by 2022 F150, 3.5L EcoBoost Tow Max FX4 Lariat Travel with one Standard Schnauzer and one small Timneh African Gray Parrot, retired mechanical engineer
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04-25-2008, 07:50 PM
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#10
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Senior Member
Alpine Owners Club
Join Date: Dec 2001
Location: Las Vegas, NV
Posts: 1,100
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Jerry,
The problem is not that these systems don't work, ("even if I have no symptoms") but that don't work like they should and can. At $4.00+ a gallon I don't want to run Aqua Hot or generator anymore than necessary.
Dale
__________________
Dale Gerstel
AMG GTS
Las Vegas, NV
Had: 2007 Limited SE 40fdts
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04-27-2008, 04:10 PM
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#11
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Senior Member
Alpine Owners Club Newmar Owners Club
Join Date: Oct 2005
Location: Fremont, Ca
Posts: 1,325
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Dale,
I understand completely. Again, that's why I love the forum because it gives me so many ideas that I would never know about on my own. It's more help than WRV ever was, at least for me.
__________________
Jerry & Judy, Fremont, California
2017 Dutch Star 4018
Freightliner, HWH Active Air
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