StuartO Posted September 24, 2014 Share Posted September 24, 2014 We specified Dometic rooftop aircon when we bought our new MH eight years ago and it hasn't had all that much use - and I haven't read the instruction book yet, which might explain my limited satisfaction. Mostly it works as advertised, so within the coooling capacity which it has (it is designed to draw a modest electrical current) it certainly does some cooling. But it really hot weather, which is when you want to use it, it only manages to cool by a few degrees, providing you also take steps to mitigate solar heating, by closing window blinds etc. So in very hot weather, providing you have an electrical hook up of 5 amps or more, it does a worthwhile job. But a couple of years ago, having not used it for a while, I bacame convinced it wasn't working properly and got it looked at by our local MH/caravan technical specialists in Clitheroe, who gave it a thorough testing. They by-passed the normal thermostatic cut-out (to get it running continuously) and achieved perfectly adequate output temperatures. So no repair was necessary and I was reassured. We're in France at the moment and it has been hot, with temperatures close to 30 degrees Celsius. We've been on a site with a generous electrical supply so we could run the aiircon and did so. It worked very well over several days of interittent use and one day we left it on all the time - so it ran for ten or twelve hours, again without problems. But the following morning when I switched it on it overloaded the circuit breaker on the supply (said to be 10 amps) and when I tried a different supply the same thing happened again twice. The aircon started up normally (quietly, fan on but no compressor) while it did it's start up sequence then as it compressor kicked in everything went off. It looked like some sort of internal failing so I gave up on it. We went roaming for a week or so, using aires, then when I came back to the same site again, en route home, I decided to try again - mainly because another test while it was still relatively warm, would proabably give useful information for pruposes of briefing the repairs when we got back to UK. Surprisingly, the aircon simply started up normally and worked as it should. Everything was back to normal. The heating element tested satisfactorily too. The aircon worked properly for several hours before being switched off. It was a pleasant surprise. So Dometic roof top aircon does seem to be both broadly reliable and worthwhile as a MH accessory (providing you can afford the weight off your payload of course) and although I have in the past said I wouldn't bother agin, this holiday it has certainly proved it's worth. But it does seem to have a need to have a day off occasionally, which I suppose isnt the end of the world. Has anyone else suffered mysterious apparent failures? Link to comment Share on other sites More sharing options...
Guest JudgeMental Posted September 24, 2014 Share Posted September 24, 2014 if you don't run an a/c units regularly the lubriccating oil added to the refrigerant does not circulate to maintain the seals...don't use it - loose it Link to comment Share on other sites More sharing options...
StuartO Posted September 24, 2014 Author Share Posted September 24, 2014 Doubtless you are correct but does that have any relevance to the scenario I encountered? There have been long periods when my roof aircon hasn't been switched on at all, maybe even as long as a year, so I will try to remeber to put it on regularly in future, because what you say makes sense. But I can't see how that risk (of failing to circulate lubricant) could explain my recent experience because the unit had worked properly (and pretty intensively) for several days before it played up and then did so again afterwards, with no maintenance in between. Lots of people have these units and I wondered if anyone else had experience of mysterious failings. Link to comment Share on other sites More sharing options...
Guest JudgeMental Posted September 24, 2014 Share Posted September 24, 2014 In answer to your first question are a/c systems reliable - yes if they are looked after maybe you have lost refrigerant and it just takes longer to circulate and produce some cool air. only way is to service/pressure test, add more oil and refrigerant. maybe worth while to check the air intake not blocked by leaves etc.....Have you had the lid off Link to comment Share on other sites More sharing options...
StuartO Posted September 24, 2014 Author Share Posted September 24, 2014 JudgeMental - 2014-09-24 12:44 PM In answer to your first question are a/c systems reliable - yes if they are looked after maybe you have lost refrigerant and it just takes longer to circulate and produce some cool air. only way is to service/pressure test, add more oil and refrigerant. maybe worth while to check the air intake not blocked by leaves etc.....Have you had the lid off Not sure you have read or understood my post properly - when it has been working it was working well (ie cooling effectively) and it was only the morning after (as it were) on one occassion that it failed electrically, by tripping the circuit breaker repeatedly, so by trying to draw more than ten amps as the compressor kicked in. When it was checked b Leisuretech a couple of years ago (because I thought it wasn't cooling and asked them to check the pressurisation I'm sure they would have had the lid off. I have also cleaned the air filters (which are easily accessible from inside the MH) myself. Link to comment Share on other sites More sharing options...
Guest JudgeMental Posted September 24, 2014 Share Posted September 24, 2014 no I did understand I think.......but there is no mystery, if its not working its either down the the available power..remember power availability in amps goes up and down according to demand on busy sites....Or something wrong with the unit/compressor .....whatever. they don't last forever. I can only post from my perspective having had problems with a/c systems in the past....i'm no engineer. Brambles hot on electrical stuff.... Link to comment Share on other sites More sharing options...
thebishbus Posted September 24, 2014 Share Posted September 24, 2014 We had a strange intermittent fault with our roof Electrolux aircon. It would work on some hookups but tripped others. At first I thought it was just because the 4/5 amps it was drawing was too high for the supply, but when I found it tripping 10 amp hookups I new it was something else. The fault turned out to be a slight earth leakage in the heater, the live is still connected to the heater when on aircon. A new heater cured the fault. Brian B. Link to comment Share on other sites More sharing options...
StuartO Posted September 25, 2014 Author Share Posted September 25, 2014 That sounds useful to know, thank you. Link to comment Share on other sites More sharing options...
lennyhb Posted September 29, 2014 Share Posted September 29, 2014 Would of helped if you had checked the mains voltage when it failed, it's not uncommon for the voltage on French sites to go down to 180/190 volts at peak times and if the voltage drops the unit would draw more current, for the same power. i.e 2300 watts at 230 v is 10 amps at 180 v it would take 12.8 amps. The start up current of the compressor will be a lot higher than the running current so although the unit may run at 5 amps the start up current could be much higher. Link to comment Share on other sites More sharing options...
StuartO Posted September 29, 2014 Author Share Posted September 29, 2014 I'm afraid I didn't think of doing that, although I did have a multimeter with me so could have done easily enough. I didn't notice any other indication of voltage drop in the supply at the time. Link to comment Share on other sites More sharing options...
steve101 Posted September 30, 2014 Share Posted September 30, 2014 Ours works really well so I would say yes. It is like a car air con and as someone mentioned above. If you don't use it you lose it. It circulates the oil around the seals if this is not done regularly then the seals can dry out and that's when problem occur. A service on them every now and then helps! Link to comment Share on other sites More sharing options...
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