Gregors Posted November 14, 2017 Share Posted November 14, 2017 Hi All, I recently purchased a Pilote motorhome knowing that there was an issue with the air-conditioning in the back. Basically when the unit is on and what sounds like to compressor goes to kick in the unit fails however the power stays on. Has anyone got any experience with these sorts of faults from there own dealing with air con ! Many thanks Chris Link to comment Share on other sites More sharing options...
thebishbus Posted November 15, 2017 Share Posted November 15, 2017 More information required I think, Which make / model aircon unit is it. When you say the power stays on, do you mean that it does not trip out or blow a fuse.? Brian B. Link to comment Share on other sites More sharing options...
Alanb Posted November 15, 2017 Share Posted November 15, 2017 I do not have any experience of these air conditioning units, however by making a comparison with compressor operated domestic fridges some points come to mind, and while the following may not help fix the problem, it may point towards it. I assume that what is happening is that the compressor is failing to start, and that the control system is shutting the unit down, with a failure indication. Small single phase AC electric motors as used to power the compressor require a starting device. This is commonly in the form of a second (starting) winding connected via a current sensing relay, which closes at switch ON, and opens when the motor is running and the current has dropped. The starting relay can fail. In the past I have successfuly repaired a domestic fridges by replacing the relay. Also many years ago, we had to call the maker's service technician to a domestic fridge that had failed under warranty. After some preliminary checks, the technician produced a builders lump hammer. He quickly explained that the compressor units somtimes stop at top dead centre, and cannot reststart. The attempted cure was to give a sharp tap to the compressor unit as it was trying to start. Unfortunately the "tap" did not work, and the fridge had to be degassed to allow changing the compressor unit. Recently a family member had a faulty dehumidifier compressor which failed to start. This was found to use a capacitor in series with the starting winding. We identified the capacitor which had partly melted, but were unable to source a replacement. Alan Link to comment Share on other sites More sharing options...
starvin marvin Posted November 15, 2017 Share Posted November 15, 2017 Gregors - 2017-11-14 12:29 PM Hi All, I recently purchased a Pilote motorhome knowing that there was an issue with the air-conditioning in the back. Basically when the unit is on and what sounds like to compressor goes to kick in the unit fails however the power stays on. Has anyone got any experience with these sorts of faults from there own dealing with air con ! Many thanks Chris Just take it to a specialist a/c mister. Simples Link to comment Share on other sites More sharing options...
StuartO Posted November 15, 2017 Share Posted November 15, 2017 Our roof aircon seemed to be playing up some years ago, switching itself off when the compressor kicked in. It's a Dometic system and the normal startup sequence is a quiet period with a bit of fan noise for a minute or so then a lot more noise as the fan speeds up and the compressor starts. I can't remember the detail but I took it to a MH workshop and they serviced and tested it throughly (at my request) and it worked normally - and it has continued to work reliable ever since. No real discovery of the cause of what seemed to be a fault but wasn't. I should take yours to a suitable workshop. The one I used was in Clitheroe, Lancashire. The other coment I would make is that roof aircon has been the least useful accessory we've fitted and it isn't really worth its weight, which is considerable. It's only usable when you are on EHU, so only on camp sites mostly, and it is noisy - so my OH won't allow it's use at night. A battery powered fan on your bedside table is much better value! Link to comment Share on other sites More sharing options...
Geoff Cole Posted November 15, 2017 Share Posted November 15, 2017 Hi, If your air-con unit is low on gas the compressor will cut out to protect the system .This is the first thing to check before you go ripping things apart and not something you can do your self. You should be able to get this checked and refilled if necessary at a vehicle air-con specialist . Geoff C Link to comment Share on other sites More sharing options...
StuartO Posted November 16, 2017 Share Posted November 16, 2017 Geoff Cole - 2017-11-16 10:23 AMHi, If your air-con unit is low on gas the compressor will cut out to protect the system .This is the first thing to check before you go ripping things apart and not something you can do your self. You should be able to get this checked and refilled if necessary at a vehicle air-con specialist .Geoff C Do you know for sure that MH roof aircon units shut down if the gas pressure is low or are you just theorising? I assumed that low gas pressure was my roof unit's problem when I took it in but they checked and it wasn't. My experience with car aircon is that they fail by no longer delivering cool air if the gas pressure is low, rather than packing up. Car aircon units are mechanically driven via a belt and have an electrically controlled clutch inside the pump unit; I suspect that MH units are more akin to domestic mains-powered aircon and are fundamentally different. Automotive garages use re-gassing units which are in large floor-bound cabinets designed to be wheeled up close the the vehicle's engine compartment to connect up; I doubt they would have pipework long enough to reach a MH roof mounted unit. Link to comment Share on other sites More sharing options...
Charles Posted November 16, 2017 Share Posted November 16, 2017 StuartO - 2017-11-16 8:22 AMGeoff Cole - 2017-11-16 10:23 AMHi, If your air-con unit is low on gas the compressor will cut out to protect the system .This is the first thing to check before you go ripping things apart and not something you can do your self. You should be able to get this checked and refilled if necessary at a vehicle air-con specialist .Geoff C Do you know for sure that MH roof aircon units shut down if the gas pressure is low or are you just theorising? I assumed that low gas pressure was my roof unit's problem when I took it in but they checked and it wasn't. My experience with car aircon is that they fail by no longer delivering cool air if the gas pressure is low, rather than packing up. Car aircon units are mechanically driven via a belt and have an electrically controlled clutch inside the pump unit; I suspect that MH units are more akin to domestic mains-powered aircon and are fundamentally different. Automotive garages use re-gassing units which are in large floor-bound cabinets designed to be wheeled up close the the vehicle's engine compartment to connect up; I doubt they would have pipework long enough to reach a MH roof mounted unit.I think that's why Geoff said "specialist" AC garage. Any engineers that have to use some kind of machine to charge a car AC system certainly aren't specialist. It's impossible to say what's wrong with it without a detailed description of what happens at start up, does it trip anything? Unusual noises? Are there any error codes or flashing LED's? Usually fixed speed AC systems have a permanent run capacitor on the compressor start winding, there's no current relay. House AC systems don't have LP switches but do have temperature sensors on the heat exchanges so the microprocessor knows an abnormality and will shut down and display an error code. I've never worked on a motorhome system so they might be different. Link to comment Share on other sites More sharing options...
Charles Posted November 16, 2017 Share Posted November 16, 2017 Also the microprocessor knows how much current the compressor and fan motor are using so it can shut down with an 'over current' fault code. Link to comment Share on other sites More sharing options...
davidmac Posted November 16, 2017 Share Posted November 16, 2017 Hi my old Luxor motorhome had a roof mounted Dominic air con unit that we never used much because of the noise it made but I was having the cab air con regased so I gave it a try out to see if it worked but it did not seem to. I took the cover off of it but could not see any connectors that looked like regasing points. Put the cover back on and switched air con on and after about ten minutes it started to cool down so all was ok just takes a time to get going. As I could not see anything that looks like the the gassing points on my car or m/h I do not know if it is possible to regas the unit. Regards David Link to comment Share on other sites More sharing options...
Charles Posted November 16, 2017 Share Posted November 16, 2017 davidmac - 2017-11-16 3:19 PM Hi my old Luxor motorhome had a roof mounted Dominic air con unit that we never used much because of the noise it made but I was having the cab air con regased so I gave it a try out to see if it worked but it did not seem to. I took the cover off of it but could not see any connectors that looked like regasing points. Put the cover back on and switched air con on and after about ten minutes it started to cool down so all was ok just takes a time to get going. As I could not see anything that looks like the the gassing points on my car or m/h I do not know if it is possible to regas the unit. Regards David There's a 4 minute ish start delay to protect the compressor against trying to start up with a high head pressure. The charging points on a car since the introduction of R134a (about 1990) have been snap on type. Older cars and refrigeration systems have 1/4" gauge access points. Newer R410a AC systems (since about 2005) have a bigger thread but very similar. If they haven't got gauge ports it's easy to braze in a 1/4" T piece and charging stub in the suction. Anything can be recharged. B-) Link to comment Share on other sites More sharing options...
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