Old & temperamental roof air

[Woody]

Maybe it caught it from me but one of my roof airs is Old and Temperamental.

Any experts out there - it comes on strong sometimes and will run for half an hour or so. The next time just the fan comes on, no compressor.

Unfortunately this is the center, ducted, quiet unit that should be the one most used.

Any suggestions?

[Jon Wehrenberg]

If it were me (which it is not of course) I would ask myself how old is the unit, how long I intended to keep the coach, and what does a new one cost?

Since I keep my coaches and cars and other stuff long term, I maintain stuff as well as I can but as things near the end of their life, especially if I am keeping the coach or car for a long time, I just replace the faulty item with new. These are recreational vehicles and it isn't much recreating if we are on a trip struggling to stay comfortable.

[Woody]

Jon, we should talk some time.

I have spent much of my life restoring stuff - aircraft, classic cars and boats where I do not have the option of buying new and have found that repairing old is the only choice and probably, quite often better than buying new stuff where available.

I'm sure you are correct regarding the roof airs but it's just my mind set. I did find on my last coach with Cruise Airs that repair was better.

Tad

[Jon Wehrenberg]

We share the characteristic of repairing or rebuilding as opposed to replacing, but in the case of something like a roof air, Cruise Air, or in my case a refrigerator I fix stuff up to a point and then because it is a motorhome and stuff fails when I am away from home I only do repairs that are not a reflection of the future reliability.

On my recently replaced refrigerator for example I replaced the evaporator fan, condensing fan and evaporator coil (three different repairs) so when it started acting up again I decided it was time and pulled it out and replaced it with new.

I have repaired Cruise Airs, but I also replaced all on my first coach when they hit 15 years or so of age. I am getting away from struggling with repairs when we are traveling.

On the other hand, since the coach has not lost any of its integrity I do all repairs necessary as well as a whole lot of preventive maintenance in advance of the need for a repair, such as air bag replacement.

[Reagan Sirmons]

Tad,
At one time I had a Duotherm Distributorship for mobile homes and as a small sideline we also sold roof airs. We would not do repairs. The issues were many...not the least being the poor quality of most RV roof air systems. Repairing them can be done by replacing relays and external parts but it usually is a one way deal. If the unit comes on and the compressor phases off after about 15 to 45 seconds, you have a leak in the system and with these, that is a big issue. It takes a dedicated person to repair a leak but it can be done but not always. Once the system has been violated, it is really troublesome. From what you have described, you have a relay of some sort that is failing periodically. Check your voltage meter for the 120 v's for starters as well. Again, from what you described, the encouraging thing is that the compressor does indeed come on for 15 to 30 minutes and then phases off. Recently on one of my units, the compressor would stay on after the fan had shut off. It was the control board itself ($300). It failed because of a low voltage into the coach at a RV park without proper supply. The unit can be checked from inside the coach by an informed technician. I know this doesn't help much but it is a start.

Reagan

[BenC]

Are your Duotherms original? Wow, they have lasted quite a long time if they are. Remember, the wiring to and the control system for the late 80's and early 1990's model dometics were completely different than that of today. Are your thermostats wider than tall? If so, you don't have electronics up inside the unit, rather a more simplistic circuit board with relays in a box in the return air access. Parts for these are still around, but most dealers and distributors aren't stocking them and they are considered "special order". The most common thing has been to upgrade to the newer setup with a Comfort Control Center, rather than the old analog thermostat. While the wiring is different in between the units, Dometic does offer adapters to put on the preterminated thermostat harness your coach currently has.
While some people are of the mindset that newer is cheaper, the construction of the newer Dometic units actually has improved. The inside, rather than being sheet metal, which was easily damaged/warped in shipping and handling, are now a molded ABS plastic. The unit is sturdier and less prone to fan shroud rubbing and various harmonic sounds than the older sheet metal versions. I know, many people think of plastic as being "cheaper" and will probably tend to disagree with me on this lol. Hope this information is helpful.

[Woody]

Thanks for your reply.

We have deceided to replace with new Carrier Air V as the other 2 newer units are these.

[BenC]

The only thing to consider about your choice is that Carrier has announced they are no longer going to make rooftop RV air conditioners...much to my surprise. Parts are already starting to be scarce. Just a thought, in case you weren't aware.

[Woody]

Thanks, now to find the right replacement.

[BenC]

Your options are the Dometic Penguin (low profile unit) in either heat pump (I suggest because they automatically equalize each time power is removed, so no restarting lag time or tripping breakers) or straight AC, and either the 13.5 kBTU or 15 K btu. If noise is an issue for you, consider the 13.5K model...low fan is actually LOW speed windings on the motor. The motor is 3-speed, but for the heat pumps, dometic uses only two speeds. on 13.5 the are LOW and HIGH, and on the 15k, the option says LOW, but is actually the medium speed windings, to ensure enough transfer air across the condenser coils (since both fans share the same motor).

RVProducts (Coleman reincarnated lol) also has a unit now that resembles the low profile AirV model by Carrier, with a separate, horizontally-mounted axial condenser fan like the Carrier unit. I have not worked with any of them yet, however, so have no technical information to add about them. Sorry.