Cruisair all-in-one air con not cooling

[superheat6k]

That's great stuff and 100x better than my useless ramblings. I'm going to print it off because my brother has several of these very units and I have one similar. Btw, the compressor is a copeland (scroll) and they have data on their website too. I think you're right that there is no speed control on the motor. Anyway, many thanks superheat. This is a grand forum :encouragement:

No problem - this is part of my day job, though fortunately we mostly avoid single phase nowadays.

With the scrolls it is vital you never run them backwards. Horrible tinny things, extensively developed NOT to be repairable by our industry. We did try to remanufacture them, but they are so cleverly put together and welded closed that the work to repair one exceeds the cost of new, and Copeland control about 90% of the market for smaller scrolls, sharing the larger end with Maneurop (Danfoss).

The field guide I put up yesterday was first written to provide field engineers a reference for wiring a single phase compressor. We used to get so many back with start up faults because the engineers just don't understand how single phase motors work. If you mix up the Start and Run terminals the start winding will burn out immediately.

Phase shift in electrical motors flys over most peoples heads, especially those dealing in the field with these tiny compressors.

Speed control is mostly done now with V/F Inverters, and many smaller AC splits and the like will have special motors matched to the maker's own inverter so they are impossible to fix. Jimmy's compressor is a simple rotary vane, and at 17,000 BTU/hr thats about 1.5 American Tons or 5 kW. The rule of thumb is 1 HP of compressor power required per American ton (12,000 BTUs/hr or 3.517 kW cooling capacity (not input energy)).

Copeland have introduced the digital scroll which uses a fast acting solenoid valve to pulse the discharge to provide capacity control, but the main control of capacity on the smaller systems is simply the fan and the thermostat that turns the compressor off when the unit reaches temperature.

No problem presently with R417A, but I expect it will become scarce in the next 5 years or so along with most other HFC refrigerants, R410A, R407C, R422D, etc, Even R134a will be mostly gone in 10 years time. Not sure what the answers will be for AC on boats, as most new gases will be flammable to one extent or another. Watch this space !

 

[jrudge]

This is almost as good as Anna geek 500 things you never knew about a battery.

The knowledge in the forum is truly outstanding.

 

[jfm]

...backed up by the forum parts supply chain. Jimmy will have new capacitor tomorrow morning

 

[rafiki_]

No problem presently with R417A, but I expect it will become scarce in the next 5 years or so along with most other HFC refrigerants, R410A, R407C, R422D, etc, Even R134a will be mostly gone in 10 years time. Not sure what the answers will be for AC on boats, as most new gases will be flammable to one extent or another. Watch this space !

I don't think flammability is a serious issue Trevor. Daimler tried this tack with the German authorities, and have only proven that 123af is less flammable than engine coolant, pas fluid and brake fluid.

 

[jimmy_the_builder]

...backed up by the forum parts supply chain. Jimmy will have new capacitor tomorrow morning

Right-o. Thanks to jfm's personal chandlery I now have a 20+3 run capacitor; is this a safe substitute for the existing 25+5? I'm inclined just to give it a try, on the basis that if the compressor itself is nfg (as I suspect) then I've kinda got nothing to lose.

 

[jimmy_the_builder]

Right-o. Thanks to jfm's personal chandlery I now have a 20+3 run capacitor; is this a safe substitute for the existing 25+5? I'm inclined just to give it a try, on the basis that if the compressor itself is nfg (as I suspect) then I've kinda got nothing to lose.

Ok. Tried it. Didn't work. Must be the compressor itself.

 

[jrudge]

To prove that can you get your controller to run jfm compressor ?

 

[jimmy_the_builder]

To prove that can you get your controller to run jfm compressor ?

Not, not readily. I'm at the point where I need to admit defeat - we haven't found a root cause of the failure, and changing the compressor is complicated, so I'm going to come back down next week and meet with Phil Hooper and give it to them to resolve.

 

[jrudge]

Was wondering if you could just run wires form your board to the other compressor. It starts ( for a second or 2) or it does not.

 

[superheat6k]

There will be revised rules in the new version of EN378 when this comes out.

The use of flammable refrigerants will likely be determined by free volume of air within a given space governing the quantity of refrigerant that a system will be able to hold.

In this regard boats are very different to cars, where most of the AC kit is in free atmosphere, not an enclosed space.

Regardless many of the gases in current use will not have viable non HFC replacements, notably R407C and R410A.

R134a already has R1234YF and mid blends with higher Global Warming Potential CO2 tonne ratings per KG.

We are advising our industrial clients not to use R410A as new equipment. Most former new stuff that was using R22 / R407C is now designed for use on R134a.

R22 replacements such as R417A, R422D and R438A will likely not have further long term replacements.

The complexity of the new F Gas rules is that it has been calculated on the CO2 tonnes number for each refrigerant, and the higher the number the less available it will be. R404A will be banned from 2020. Trying to explain these rules to layman is very difficulty.

Marine leisure use of refrigerants is a tiny tiny fraction of refrigerant volume. The biggest issue will be for those with existing systems trying to maintain them when they lose their gas for some reason after say 8 - 10 years service.

This is a changing picture, and I don't expect the Brexit decision will affect anything seen as environmentally beneficial, although not sure this latest round of changes was that well understood by the Politicians that brought it in.

 

[superheat6k]

Ok. Tried it. Didn't work. Must be the compressor itself.

The 25 + 5 will be 25 for the compressor and 5 for the fan.

As these things have enormous tolerances a 20 is not that much different.

As your resistances are OK I suspect the controller. You need to see voltage between the common and start at start up. Have you tried the hot wiring to bypass the controller - not as permanent fix just to test the compressor.

 

[jimmy_the_builder]

The 25 + 5 will be 25 for the compressor and 5 for the fan.

As these things have enormous tolerances a 20 is not that much different.

As your resistances are OK I suspect the controller. You need to see voltage between the common and start at start up. Have you tried the hot wiring to bypass the controller - not as permanent fix just to test the compressor.

Thanks for this. I haven't tried hot wiring it yet - I was concerned by your comments about fatally damaging the compressor. I'll re-read your guidance now.

 

[superheat6k]

Thanks for this. I haven't tried hot wiring it yet - I was concerned by your comments about fatally damaging the compressor. I'll re-read your guidance now.

If you have diagnosed a duff compressor, trying to hot wire it won't do any more harm.

Wire live or neutral to the Run terminal, then connect the Cap from the Run to the Start terminal (use the higher MFD connections).

Then when you are ready connect the opposite feed (Neutral or Live) to the common using a switch in the feed, or even just a socket plug.

Clamp the amps on the start feed, this should show about 2-3 a initially then this will reduce to about 0.5a if the compressor runs, but you will know immediately.

If it hasn't started straightaway turn it off.

Leave for 5 minutes then repeat this time with the hard start device in parallel with the capacitor.

Your diagnosis is a seized compressor, but until you see some power on the start winding you cannot be sure of this. If the start winding is not receiving power via the Capacitors then the motor will oscillate at locked rotor amps (as observed already), but won't start.

 

[jimmy_the_builder]

If you have diagnosed a duff compressor, trying to hot wire it won't do any more harm.

Wire live or neutral to the Run terminal, then connect the Cap from the Run to the Start terminal (use the higher MFD connections).

Then when you are ready connect the opposite feed (Neutral or Live) to the common using a switch in the feed, or even just a socket plug.

Clamp the amps on the start feed, this should show about 2-3 a initially then this will reduce to about 0.5a if the compressor runs, but you will know immediately.

If it hasn't started straightaway turn it off.

Leave for 5 minutes then repeat this time with the hard start device in parallel with the capacitor.

Your diagnosis is a seized compressor, but until you see some power on the start winding you cannot be sure of this. If the start winding is not receiving power via the Capacitors then the motor will oscillate at locked rotor amps (as observed already), but won't start.

Can I try this test using the 25mf capacitor that I already have here? (you previously suggested a 10mf but I don't have one).

 

[superheat6k]

Can I try this test using the 25mf capacitor that I already have here? (you previously suggested a 10mf but I don't have one).

Yes. My suggestion of 10 MFD was a bit low. I couldn't see the value on the picture of the capacitor.

If you study our field guide this explains in more detail how a single phase motor works and what the capacitors are doing. As yours has a hard start device I suspect you don't have a separate relay to switch a start capacitor. If your run cap is ~ 25 MFD then I would expect a start cap to be around 100 - 150 MFD.

I will PM you my number if you want to have a chat.

 

[jimmy_the_builder]

So, a bit of a disappointing update to the thread: I spoke to Superheat6k on the phone, brilliantly helpful, thanks T. The eventual diagnosis was either a failed hard starter or a locked compressor. I then spoke to Matt Fry at Dometic who very kindly sent me a replacement hard starter, which I tried on the boat this evening. Unfortunately this didn't make any difference, the compressor won't start and it is still pulling locked rotor amps. So it looks like it's either a replacement compressor, which is a big job - or a complete replacement all-in-one unit, which ironically is probably an easier job, but more costly. I suppose I'm a bit surprised that the unit has failed after only four seasons light occasional use. Next challenge is to actually get a local agent to come and do the job...

 

[rafiki_]

Ummm, not good J, bad luck. Hope you get a rapid solution.

 

[petem]

Yep, bit of a bummer but looks like it's been a good learning experience.

 

[superheat6k]

What current are you measuring on the start connection when the compressor starts ?

Your diagnosis might be definitive, but only if there is some current through the start winding. In view of the diagnosis I would suggest a hot wire attempt to start the compressor, and I would use a 100 - 150 MFD capacitor. If it already knackered blowing the motor won't make things worse, since for a burnout to contaminate the system the compressor has to be spinning during the burnout.

 

[Deleted User YDKXO]

I suppose I'm a bit surprised that the unit has failed after only four seasons light occasional use.

Which is why I'd be very surprised if you've got a failed compressor. I've had a number of Cruisair and Condaria a/c units on boats which have been older than 4 yrs and never had a major problem with any of them save for a sticking seawater pump and a failed condenser. I'm certainly no expert but the failed condenser caused the exact problem you've got ie the compressor not kicking in