Bus Conversion Magazine Bulletin Board

Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: Brian K on September 10, 2006, 04:49:43 PM



Title: Roof top air
Post by: Brian K on September 10, 2006, 04:49:43 PM
 I would like to ask all which you think is the best roof top air unit. I replaced one of my a/c units exactly two years ago and it has stopped cooling. the compressor keeps shutting off. I had to replace the fan motor thee months ago because the bearings seized up. Something else about this unit is that the exterior plasitic parts have deteriorated. If you want do routine cleaning or replace a part which requires the removal of the fan cover etc. the interlock tabs are brittle and tend to break easily. I want to replace both roof top air units but don't think I want another Carrier. One thing though, this unit alone when working would cool the whole bus here in south Florida during the summer and I was more than satisfied with the performance. I just feel that the major components should last a little while, partucularly if they cannot be replaced. Am I expecting too much here? Or do the new a/c units today only last 24 mo.s. All and any reply is appreciated. Thanks in advance.


Title: Re: Roof top air
Post by: NJT5047 on September 10, 2006, 05:49:57 PM
Brian, cannot tell you which is best, but I've owned both Coleman and Dometics, some were more than 10 years old, and never had a problem with any of them.  I've got two Dometic rooftop heat pumps and they are a good bit quieter than the Colemans, but both are good units.  One 15K heat pump will cool my 40' coach's salon and bath, but the bedroom may not be comfortable when it's 100* outside...both units running will cool if quite well even when running on low.   Once the sun sets, one unit more than cools the whole bus.   
My Dometics are 4 years old and have not had any issues...yet!   Two year replacement is outside the norm.  They should last a lot longer than that.  10 years is a nice number.   There are a lot of 20 year old Colemans around that still work like new. 
Once had a 5th wheel with a 13.5 Coleman rooftop. It was about minimal for the camper...the compressor would run continuously 24/7 in the summer when camping.   It was a '90 model and I sold it in '01.  The AC is still working today.     
JR


Title: Re: Roof top air
Post by: Nick Badame Refrig/ACC on September 10, 2006, 05:56:28 PM
Brian,

JR is correct that the Dometic's are a bit quieter and have 3 speed fans. It'a really personal prefrence....

Unfortunetly, Dometic, Coleman, and Carrier all design their units to last 5 years. Some more, some less.......

Good Luck with your Choice!

Nick Badame


Title: Re: Roof top air
Post by: NJT5047 on September 10, 2006, 07:01:56 PM
Nick, while the subject's up, are there any negative effects caused by operating the ACs on low or high or??? 
I reckon my question is what may damage a rooftop AC...my heat pumps were a bit on the expensive side (for rooftops) and I'd like to spare insulting them.   They stay on low fan/AC most of the time....is this bad for the ACs?   They don't seem to lug, or drag the power down when they cycle...just curious.   
Thanks, JR


Title: Re: Roof top air
Post by: Nick Badame Refrig/ACC on September 11, 2006, 07:14:54 AM
JR,

In temps above 85 deg. the fan should be ran on hi speed for maximum cooling of thr condencer coil.

If not, you may overheat the compressor.

Nick-


Title: Re: Roof top air
Post by: Len Silva on September 11, 2006, 08:01:09 AM
JR,

In temps above 85 deg. the fan should be ran on hi speed for maximum cooling of thr condencer coil.

If not, you may overheat the compressor.

Nick-

An unfortunate result of using the same motor for both fans and another reason to go with some type of split system.

Len


Title: Re: Roof top air
Post by: TomC on September 11, 2006, 08:08:54 AM
Brian- some things to consider. I have three Colemans that were installed in '94.  The only thing I have done is to replace one exterior shroud and clean the filters. Even though they cool well, they are noisy with only two speed fans.  Three would be better-like the DuoTherms.  I would consider the Penquins since they are lower.  Another unit that looks good is the new Carrier low profile which is the lowest made.  What I like about it is that it has two fan motors-compared to others with one-so that it wouldn't matter which fan speed you choose even when it is hot.  Another point- some like to have ducted air.  While that might make the A/C quieter and you don't have the diffuser hanging down, I am old fashioned with simplicity in mind.  I like the hang down diffuser with manual mechanical controls that makes for a good air flow (both of us like feeling moving air).  The one thing for sure is not to buy the heat strips (maybe they work on the DuoTherms with their low speed) since the air flows too quickly past the coils to do any good. I've even shut the vents so little air gets out and they work a bit, but better to buy two portable floor heaters with tip over switches.  I found that two of the electric heaters heat the bus very well down to 25 degree weather (the coldest I've been in). Good Luck, TomC


Title: Re: Roof top air
Post by: Brian K on September 11, 2006, 05:02:55 PM
  Thanks for the good info and input. It seems like all of the units are similar in respect to longevity and output. Maybe I just happened onto a lemon. I puchased the Carrier Air V because I read some good reports on it and some people told me this brand was quality. These things really cool good when working. I just didn't know if anyone on the board might have had the same experience with this model. Thanks again and I will look at some of the units suggested.  Brian K