Roof Air Conditioner

Topic: Roof Air Conditioner (Read 1481 times) previous topic - next topic

Roof Air Conditioner

October 11, 2010, 11:14:30 am

Has anyone purchased a replacement roof ac unit that they do not like? My original Coleman front ac unit is noisy and vibrates more than I like, but it still cools ok. The rear Coleman was replaced before I bought the coach with a Dometic Penguin which is quieter and has less vibration, but isn't that quiet. I think I will stay away from Carrier as some internet sellers have indicated that they are out of stock and that Carrier is not making any. Of course I would like to have one that is very quiet, highly efficient, doesn't vibrate, and doesn't drip water down the side of the coach, but that combination doesn't seem to be available. So far, I am leaning toward either the Coleman Polar Mach or the Mach III Power Saver, both 13,500 BTU/hr. I hate replacing stuff that still works, but I replaced one on the SOB because of the noise and vibration.

Re: Roof Air Conditioner

Reply #1 – October 11, 2010, 11:42:56 am

Jerry, Are you sure that you have COLEMAN AC's. All the FT's I have seen have the Dometic Penguin units. My two Penguins are not that noisy and have served me well for 15 years. Give FT a call, I suspect that the originals were Penguins and the Coleman is a replacement.
Vibration can be caused by fan inbalance. I had mud dauber nests in one of mine, it was in the squirrel cage and it shook badly. Also check for loose sheet metal under the shroud and other loose parts.

Re: Roof Air Conditioner

Reply #2 – October 11, 2010, 12:59:51 pm

Gary, I'm about 95% sure the original units were Coleman. The bedroom ceiling has a faint outline that matches the front Coleman air distribution box. The Coleman just looks older than the Penguin. I will check for mud daubers, but most of the noise and vibration occurs when the compressor is running. Older units used a piston type compressor, but the newer units use a rotary compressor that is quieter and vibrates less. I suppose the rubber compressor mounts could be worn, will go check that.

Quote from: Gary Bouland – October 11, 2010, 11:42:56 am

Jerry, Are you sure that you have COLEMAN AC's. All the FT's I have seen have the Dometic Penguin units. My two Penguins are not that noisy and have served me well for 15 years. Give FT a call, I suspect that the originals were Penguins and the Coleman is a replacement.
Vibration can be caused by fan inbalance. I had mud dauber nests in one of mine, it was in the squirrel cage and it shook badly. Also check for loose sheet metal under the shroud and other loose parts.

Re: Roof Air Conditioner

Reply #3 – October 11, 2010, 01:11:02 pm

Quote from: Jerry Whiteaker – October 11, 2010, 11:14:30 am

Of course I would like to have one that is very quiet, highly efficient, doesn't vibrate, and doesn't drip water down the side of the coach

Dometic makes a drain kit that addresses the condensation running off the roof

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MOT installed ours.

Since the A/Cs sit a bit higher off the roof, they are quieter. This is especially true of the recent manufacture Penguins, which in Steve's investigation have a design issue where a screw head from the compressor section is in contact with the roof, translating vibration and noise into the coach.

One slight issue with the drain kit is that in high humidity areas, that's a lot of water present on the roof, slowly draining away (through tubes that are hidden in the end cap and exit below the bottom of the coach frame). If you are driving and decelerate quickly, some water may back up and overflow the pan. Steve is working on a minor retrofit of a backflow preventing check valve to eliminate this issue.

Michelle

Re: Roof Air Conditioner

Reply #4 – October 11, 2010, 01:54:44 pm

Jerry
I have the 7300 coleman AC and the front unit is loud also. If you find a unit that is quite please let me know.
Thanks
Rick

Re: Roof Air Conditioner

Reply #5 – October 11, 2010, 02:05:22 pm

I had a vibration on front unit and it turned out to be a loose compressor mount.

Re: Roof Air Conditioner

Reply #6 – October 11, 2010, 08:20:58 pm

Went to the MH this afternoon and checked for mud dauber nests and didn't find any on the fan rotor or anywhere else. The rubber compressor mounts also looked ok, didn't feel exceptionally hard and none loose. I found a 1994 date on the compressor that is somewhat rusty, so it must be the original unit. My 96 model coach was finished in 95 according to the placard at the drivers seat.

Michelle, thanks for the info about the drain kit, didn't know it existed, but think I will pass on the tube across the roof.

Rick, your ac's look just like my Coleman.

Re: Roof Air Conditioner

Reply #7 – October 11, 2010, 08:48:25 pm

Thought since we have the same year and model, maybe they're actually the same

Yes, I too have Coleman's. The previous owners had the rear one worked on in 05 because of vibration. FOT replaced the motor and the fan, $450 worth, for what it's worth.

Re: Roof Air Conditioner

Reply #8 – October 11, 2010, 09:52:05 pm

I just replaced two AC units and also put on the remote drain kit. I have used them Now for a week with no issues. I love how there is no water dripping off the coach. I will say seeing it on he floor in the rear is very different.

Re: Roof Air Conditioner

Reply #9 – October 12, 2010, 12:01:01 pm

I have a California friend who is also a retired Engineer and like me, picky.
He removed both roof air units because of noise and to reduce the weight on the roof. He installed standard 15amp house A/C units in the basement or closet and ducted them. They are almost silent.

He also has installed Hepa air filters so all incoming air is filtered with a fan which provides slight positive pressure inside his motohome. Open door and air blows out. He boondocks in the desert all winter and when hot, covers his windows with foiled foam. It is like a cool dark oasis inside his "no dust" motohome when the temperature is 100 outside. He lives mostly inside.

Just when you think you have seen everything!
By the way, he is pickier than me, I do not even use the A/C's and live outside all winter.

Re: Roof Air Conditioner

Reply #10 – October 12, 2010, 12:29:04 pm

John, Very interested in the new air conditioners with the remote drip line. Could you tell us more as to where they run and why was it necessary to replace two units. What happened to the old units ?
Thanks
Dave

Re: Roof Air Conditioner

Reply #11 – October 12, 2010, 12:43:33 pm

Quote from: Dave M – October 12, 2010, 12:29:04 pm

John, Very interested in the new air conditioners with the remote drip line. Could you tell us more as to where they run

Dave,

Check my post a couple above John's for photos.

We had ours installed at MOT last month, mostly for condensate run-off but we also had a noise issue with our new units (replaced because of the roof "incident") and it helped with that.

The A/C have to be taken off and reinstalled to add the drain kit, IIRC.

Michelle

Re: Roof Air Conditioner

Reply #12 – October 12, 2010, 12:59:09 pm

Michelle,
Hope all is going well with the genset issue, and for the drain kit, I guess being a dim bulb, why did they not run the vent into the sewer vent line, or did I miss the point. Do like the idea of raising it slightly due to the screw head issue.
Or where did they run the hose down ?
Also being cheap and tacky, do you feel free to give me an idea of cost range for the two unit conversion ?

Thanks
Dave

Re: Roof Air Conditioner

Reply #13 – October 12, 2010, 06:44:59 pm

Quote from: Dave M – October 12, 2010, 12:59:09 pm

why did they not run the vent into the sewer vent line, or did I miss the point. Do like the idea of raising it slightly due to the screw head issue.
Or where did they run the hose down ?
Also being cheap and tacky, do you feel free to give me an idea of cost range for the two unit conversion ?

The hoses run to the rear end cap, into the cap through small holes, then the tubing exists just below the coach framing. It's a gradual downhill run so the water drains. Wouldn't running into the sewer vent drain the water into the holding tank? The idea is direct it off the roof out of the way rather than have it run somewhere down the side of the coach.

I don't immediately have the cost here - the receipt is in the coach and it's rolled in with having our slide bladders and fridge water line replaced so I'd have a hard time guestimating. I don't think I'd go for the conversion unless I was already having the A/Cs or their pans replaced already, since the bulk of the cost is in the removal and installation of the A/Cs.

Michelle

Re: Roof Air Conditioner

Reply #14 – October 12, 2010, 06:55:00 pm

Michelle, Many Tnx.
Dave

Re: Roof Air Conditioner

Reply #15 – October 12, 2010, 10:52:02 pm

Spent all day at the computer searching for info on roof ac's both Coleman and Dometic. One of the things I found is that manufacturers have phased out R-22 refrigerant and are using R-410A. As of Jan 2010 R-22 can not be used in new equipment. It will be available until 2020 to service old ac's. Looking at the data sheets for comparable size roof ac's (13,500 btu size) R-410A is not as efficient and requires 1 amp or 120 watts more power to do the same work. But R-410A may not harm the atmosphere as R-22 is believed to do and our grandkids may not get a super dose of UV rays. The good news is that most are more efficient than the ac's from 15 yrs ago. In addition to looking at data sheets regarding how much power various models use, I also looked at parts lists and diagrams. Found that the Coleman Polar series of units have a condensate pump. It wasn't until the end of the day that I found some promotional literature that actually said that condensate would not be running off the roof and down the sides of the RV. I like the style of the Polar series, it is low profile, the fan motor is mounted vertically so that the hot air from the condenser is blown straight up. It's available in 15K, 15k heat pump, 13.5K, and 9.2k Btu/hr. I have not found any RV parts sellers though that advertise or list the 15K cool only or 15K heat pump. Maybe if we ask, they are available for a price? Both Dometic and Coleman have other units that are more efficient. I think that anything made today will be quieter and have less vibration than what was on the market 15 yrs ago. Has anyone installed a Coleman Polar series AC on their coach? And if you did is it noisy or quiet?

Coleman http://www.rvcomfort.com/rvp/ Dometic http://www.dometic.com/enus/Americas/USA/RV-Products/

Re: Roof Air Conditioner

Reply #16 – October 12, 2010, 10:55:19 pm

I replaced both original Coleman Mach units because I couldn't get to the bottom of constantly tripping the ATS when trying to start both units while on generator. Changed ATS, no result. Tested the genset 9 ways to Sunday and no problems found. The original units worked great on shorepower. Very cold air. Tested power consumption and there was a big spike on compressor start on each. Replacements are Coleman Power Savers with supposedly lower spike on compressor start. My problem is much better but still have the ATS issue once in a while on compressor start when one unit is already running. The air from the new freon free units is not like the old freon units. I don't understand it as the thermometer shows them putting out cold air but there is something different about them that does not cool it down as quickly and the air just feels different. I would fix up the older freon units before buying new if I were you. Just my 2 cents.

Re: Roof Air Conditioner

Reply #17 – October 13, 2010, 01:18:40 pm

Quote from: Dwayne – October 12, 2010, 10:55:19 pm

The air from the new freon free units is not like the old freon units. I don't understand it as the thermometer shows them putting out cold air but there is something different about them that does not cool it down as quickly and the air just feels different. I would fix up the older freon units before buying new if I were you. Just my 2 cents.

I don't doubt what you are saying. The chemists and chemical engineers have their work cut out. The freons were destroying the ozone and now the newer stuff is helping to cause global warming. The replacements don't work as well, require larger coils, etc. The R134A used in cars will be phased out in Europe starting 2011. Prior to freon, ammonia and sulphur dioxide where the main refrigerants. My parents had a refrigerator that used sulphur dioxide, and lasted a long time. The inventor of freon would breath the stuff to prove its safety and promote the product. Propane can be used as a refrigerant, but a leak is not good due to the flammability factor. Carbon dioxide could be used except that pressure in parts of the system would be up around 1000 psi.

I don't think it would be economical to fix the old Coleman. Most of the parts are probably near the end of their life. The price of R-22 will go up with decreased use.

Re: Roof Air Conditioner

Reply #18 – October 13, 2010, 02:01:47 pm

Wow. This does not paint an encouraging picture for those of us with older coaches who do not want to buy a new one.

Re: Roof Air Conditioner -- Rear Unit Not Working

Reply #19 – October 13, 2010, 04:07:04 pm

Well, DW just informed me that our rear AC unit is not working. Nada, zip. It does not respond to the thermostat.

Are there any basic trouble shooting things I can do?

Re: Roof Air Conditioner

Reply #20 – October 13, 2010, 04:30:41 pm

George,

Check that BOTH legs of your 50amp service are supplying power. If you are hooked to 30amp, or if the "second" leg of your 50amp service fails, the rear air conditioner will not run.

Check circuit breakers as well.

Re: Roof Air Conditioner

Reply #21 – October 13, 2010, 04:43:09 pm

JD

We are on 50 amps and the ECM shows power on both legs. I also opened and closed the circuit breaker. No luck. Is there anything top side I should check out?

Thanks,

George

Re: Roof Air Conditioner

Reply #22 – October 14, 2010, 08:01:48 am

George,
Depending on the type of thermostat they can be cranky and that would be the first place to start to troubleshoot. You will need to provide the model or type of thermostat that you have for that A/C to determine how to get around it to fire off the unit.
Wiggling and giggling the switch on the thermostat may get it to run.
Maybe post a picture of the thermostat, and someone might have specific info on it.
Good luck,

Re: Roof Air Conditioner

Reply #23 – October 14, 2010, 09:29:42 am

Quote

Our rear AC unit is not working. Nada, zip. It does not respond to the thermostat.

George if you have a 4 button thermostat this might help.
http://beamalarm.com/Documents/duo_therm_control_center_repair.htm

Re: Roof Air Conditioner

Reply #24 – October 14, 2010, 09:51:31 am

Duo Therm 5 Button Comfort Control. I just tried to turn on only the fan. No response. I'd be happiest if it were just an issue with the thermostat.

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