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bkahler 04-07-2010 08:41 AM

Time to replace our A/C units on the 310
Well it痴 time to replace both A/C units on our 1984 310. Obviously there are a lot of choices out there. Susan and I have talked it over and have come to the conclusion that we can稚 justify the large price differential between the low profile units compared to the standard height units. So that only leaves two questions. one is do we use 13.5k or 15k units and what brand should we buy. Looking at the amp ratings it appears that the 15k units draw around 15.2 amps and the 13.5k units draw around 13.5 amps. At this point I知 of the opinion that considering the quality (or lack there of) of most outlets in the campgrounds trying to use a 15.2 amp unit would present more problems than it would solve.

For those of you using 15k A/C units have you had any problems with shore power circuit breakers tripping? Also I知 concerned that our 7kw Kohler generator would not be able to handle two 15.2 amp loads, heck it struggles with two 13.5 amp loads at the same time L

Other issues I知 concerned about is making sure we get a unit that has a trip pan suitable for use on the curved roof of the Airstream.

Any ideas and/or suggestions would be greatly appreciated. I would especially like to see comments on the 15k vs 13.5k issue and the brand to buy.



Mike Leary 04-07-2010 09:56 AM

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You'll have to do some checking. When we replaced our Colemans, we were told the only AC that would fit was the Dometic "penguin" 13.5 unit. With a heat strip, air distribution box and pan, it came to around $1,000 each. I like the low profile, though.

kmpro 04-07-2010 10:17 AM

Time to replace our A/C units on yhr 310
I had 15K A/C Heat Pumps on my Diesel Pusher and could'nt have been happier with them. Current draw was not a problem, as I had 50 Amp service on the unit. Most of the time one a/c would cool the 40 footer but insulation was much more of a factor on that coach. My pick would be 2 15K units then you would have plenty of air for any situation. In this case, I think more is better. My .02 worth

345bill 04-07-2010 10:37 AM

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Brad- We too like the looks of our Coleman low profile as it also has the heat strips compared to the Coleman up front that is an A/C unit only. However as far as cooling goes there is no comparison that the Carrier cools far better, on mine.

My 6.5 Onan struggles when trying to run both at same time and occasionally will trip breaker (at Onan) at which time I usually just cut back to using the Carrier by itself.

Condensation isn't a big deal here in the desert but the times we've had it back east the Carrier does put out alot of water as I usually see a puddle of water outside where it drains on driver side of coach.

It might be hard to visualize from this pic. but my intention was to show you the height difference between the two.

Mike Leary 04-07-2010 12:48 PM

We've had no tripping of the gen set with the Dometics, but it happened with the Colemans; I suspect the Colemans were 1500 as they did cool better. Nothing against the Dometics, though, they are very quiet; been in for five years.

345bill 04-07-2010 03:41 PM


Originally Posted by 345bill (Post 834873)
Brad- We too like the looks of our Coleman low profile as it also has the heat strips compared to the Coleman up front that is an A/C unit only.

...from previous post I meant to say the Carrier up front, that is A/C only.

choctawmel 04-07-2010 04:41 PM

I got a 15K Carrier to replace the 13.5 Coleman on the living/kitchen area of Silver Bullet. I have re-wired her with a 50 amp plug and have had no problems running both the old rear 13.5k Coleman and the new front 15K Carrier going through a 50-30amp adapter. The Carrier has a drain tube in it, so no pan is needed. The Carrier is quieter inside and out. After three months in New Orleans, wish I'd got the heat pump version though.

guy99 04-07-2010 04:48 PM

I recently had 15,000 BTU Dometic put in the front. Airstream supplies a drip pan that works with this unit. No problems running it on shore power. If I run both the new Dometic in the front and the old rear Coleman on the generator, occasionally the generator breaker for the rear unit will trip. I have a Honda EV 6010 which has one 30 amp and one 20 amp breaker.

I put a meter on the rear unit and watched the current draw as it ran, what I observed was higher and higher peak draws when the compressor started. Don't know if this is the normal result of back pressure as the unit get hot or a defect in the unit. I suspect that on occasion this starting load is enough to trip the 20 amp breaker.

GlenCoombe 04-09-2010 06:15 PM

I to have the 15K AirV Carrier and have been very happy with it. I have it ducted down the center with two vents in the center drop down ceiling and a opening at the end of the run for the cockpit. The unit has been bulletproof and runs well on the Honda6010 though I only have the single unit in the 28'er.

Bigger is better and the draw difference is not that much IMO.

Sounds like two 15K units and a new generator are in the future..... could be wrong there though.

guy99 04-11-2010 01:21 PM


Originally Posted by GlenCoombe (Post 835845)
... I have it ducted down the center with two vents in the center drop down ceiling and a opening at the end of the run for the cockpit. ....

I'd love to see pictures of your vented system. Do you think you experience any lose of cooling due to the venting?

Does the venting make the AC any quieter?

GlenCoombe 04-11-2010 02:16 PM

I think I've posted photos in the past and vents are hard to show. The entire center section of the headliner is a swing down and I just moved some wires out of the way and opened a hole at the end of the trough. I opened two holes along the trough and connected to the plenum at the bottom of the unit. (on inspection of my gallery posts I see that I've not posted photos of the a/c install and vents. The original photos will show the section of headliner that creates the center channel vent. I'll see if I can't take some additional photos soon.)

I vent the majority of the a/c into the back of the coach and the unit is located on the 2/3rd mark so the noise is very much less than a unit up front. There is a certain amount of parasitic loss but I've tried to smooth out the center channel with a/c foil tape. Anytime you try to bend air there will be loss.

Driving into the sun westbound in the p.m. can show some loss of cooling but I have a dash fan to blow on my body and help the dump from the a/c above to find home.

While far from perfect it works and as we all know the issue is more of insulation than of cooling or heating with AS and as my coach is heavy on glass the solar gain is what took me to the bigger 15k unit.

jking 04-14-2010 06:18 PM

Glen, that sounds like a very fine modification - please let's have more details and pics.

bkahler 04-15-2010 05:54 AM

First off I apologize for starting this thread and then leaving town. We went racing at Virginia International Raceway from the 8th thru the 11th so I got wrapped up in fixing and then packing the motorhome. Fortunately while at the track we only had to use the A/C for a few hours on Saturday and we got lucky and the rear A/C unit actually worked!

All of your responses have sparked a few more questions.

It looks like my options are as follows:

Dometic, Carrier or Coleman
Heat pump/non heat pump
Heat strip/no heat strip
Standard profile/Low profile

Due to the water heater having failed while pressurizing the system just prior to this trip (big leak from poor winterization) it looks like we will only be replacing one A/C unit at this time. We値l probably wait until fall to do the second unit.

It sounds like the 15K units definitely do a better job of cooling. That does make sense based on the 1.5K additional capacity. I値l have to talk to Susan but I知 now wondering if we shouldn稚 install one 15K unit up front and a 13.5K unit in the rear. When traveling we like to use the front A/C unit to help keep things cool inside. Now I need to decide whether we can justify the cost for a low profile unit. I doubt that we will bother with the heat strips. I just installed a new furnace and was pleasantly surprised at how comfortable the coach felt while using it. Prior to replacing the furnace we had been using a small 1.5K ceramic electric heater. BIG difference!

I知 also not sure we could justify the difference in price for a heat pump unit. I知 not sure what the advantage would be for us over a standard unit.

One question I forgot to ask initially was whether these units are designed to fit the inside curvature of the Airstream ceiling. Any comments?



raveson 04-15-2010 06:47 AM

air ?s
I replaced the rear original unit with a Colman mach (not low profile) 13K unit. The amount of air compared to the old one was much better. The install was easy once I got the new unit up on the roof. My only dissapointment is that with coleman, you can not reattach the drip tube so as not to run the drip over the roof. The inside cover is smaller then the orig coleman low profile and actually fits better. When the front one is going to be replaced, I believe I'll opt for the 15K to enhance the cooling when traveling. The front unit works ok, but the drip pan leaks to the interior, and the only way to repair or replace it is to remove the unit and if I go to that trouble, I will replace it!

kmpro 04-15-2010 11:25 PM

Time to replace our A/C units on yhr 310
Brad, I had 15K Heat Pump units on my pusher, and we used the heat pumps for heat until the temp went to about 36 degrees. After that, it was furnace for heat. The A/C was great going down the road, and we seldom had to use the dash air as a result. Gen used less fuel than dash air so it was good for us. I think 15K up front is the ticket to stay cool.

Smartstream 04-16-2010 12:16 AM

I replaced the original unit on our 28' with a Carrier 15K low profile. I wanted a heat pump but it wasn't available in the low profle. The low pro looks so much better sitting on the roof I'm glad I passed on the heat pump. My furnace works great and I don't have to be plugged in.

The install was easy. I basically trimed the edge of the old plastic pan and set the Carrier right on top. I did have to make a wood shim to mount the inside cover to the ceiling curve. There is a thread on the forum somewhere with pics of the install but I don't remember who posted it.

Good luck, Dan

345bill 04-16-2010 08:45 AM

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Originally Posted by bkahler (Post 837997)

One question I forgot to ask initially was whether these units are designed to fit the inside curvature of the Airstream ceiling. Any comments?



Brad- Hope the races went well for you guys.

Here's a couple pics of the interior fit. The pic on top is the Carrier, located on front of MH, while the Coleman w/heat strips is bottom in pic located on rear of MH.

The Carrier pic here really doesn't do it much justice as that visible gap at ceiling really isn't as drastic as it appears here although the Coleman is a better fit, inside.

To be honest neither unit has given us any problems ( other than we had to change the 'squirrel' cage once on the Carrier) that involved having to go up on roof so I can't honestly tell you about drain tubes/drip pans. I do know when were in high humid areas all of the condensation exits outside as we never found anything wet inside.

pwhittle 04-24-2010 05:54 AM

I recently replaced both units with 15000 BTU standard profile Carriers with heat strips. These are generally available at pretty good pices through the online sources (eBay,etc).

I was fortunate to pick up a new pair for a very good price, then sold my one working old unit to recoup some money and ended up only spending $650 net for both units.

No issue with running them both on my 6500 Onan or one of them on 30 Amp shore power.


soldiermedic 04-24-2010 06:54 PM


I just saw this thread. I think you would be great going off with the Carrier low profile units like you helped me install on my unit in Branson. Get them in the next couple of weeks and I'll help you install them at the rally :)


gunner 04-25-2010 06:18 AM

I was in the same position you are in, my rear air conditioner would work intermittently. I was at the point of replacing both having phoned Airstream, Jackson Center for a quote and obtaining advise on this forum. I decided to have a local home airconditoner repairman look at it and he found that my original Coleman air conditioners already the fittings for adding freon, I did not need additional freon. What he found was one of the capacitors was weak, low reading. He replaced it and everything worked fine after that. This saved me a lot of work and money.

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