Cruisair all-in-one air con not cooling

[rafiki_]

Time to get another boat J

 

[jfm]

VF looks very nice - you are visible loud and clear!
I dunno what to suggest re airco. When the control board demands compressor, are you getting 230v at the compressor motor? I think that's pink and white/red but I'm not sure because I think there is a switching transistor thing there that chops the A/C sine wave to control speed. Not 100% sure but the three wires and the "SCR" on the diag suggest this. You'd still see some RMS ac voltage though if you used an ordinary multimeter, even if not 230, if the compressor has been asked to run

 

[jimmy_the_builder]

VF looks very nice - you are visible loud and clear!
I dunno what to suggest re airco. When the control board demands compressor, are you getting 230v at the compressor motor? I think that's pink and white/red but I'm not sure because I think there is a switching transistor thing there that chops the A/C sine wave to control speed. Not 100% sure but the three wires and the "SCR" on the diag suggest this. You'd still see some RMS ac voltage though if you used an ordinary multimeter, even if not 230, if the compressor has been asked to run

Thanks J. I'll get a meter on it when we are back on berth. For now, however, faced with gruelling F1 winds and overnight lows of 22c, we have decided to tough it out at VF tonight

 

[jfm]

Thanks J. I'll get a meter on it when we are back on berth. For now, however, faced with gruelling F1 winds and overnight lows of 22c, we have decided to tough it out at VF tonight

When are you back on berth? Do you want me to get jenny to deliver the dji? Is in my garage ready to rock. You need an ipad ideally, or a phone. Dji Go from the app store. And a usb lead

 

[jimmy_the_builder]

When are you back on berth? Do you want me to get jenny to deliver the dji? Is in my garage ready to rock. You need an ipad ideally, or a phone. Dji Go from the app store. And a usb lead

Ooh yes please. We'll definitely be back late Friday afternoon because we are suppering in Vauban. Shall I call her to find a convenient time?

 

[jfm]

Yep. Let me text her first as she knows nothing of this. I'll text you

 

[superheat6k]

SCR on the compressor refers to the connections Start Common and Run. The start capacitor connects the power from the run terminal and causes a phase shift to make the compressor turn.

If you have power at the compressor it should run.

To have the thing in permanent cooling I would suggest the wire from the controller to the reversing valve 2nd from right should be disconnected, but this won't stop the compressor running. A stuck reversing valve can cause LP trips, and a light tap with a mallet might release it.

I would check to see if you have both HP and LP switches (not shown in the photos) and see if these have small rubber dimples on the side opposite the pressure connection. If so press these and see if the thing starts.

Running in dehum mode simply runs in cooling mode at low fan power, causing a cold cooling coil with low fan speed, so the moisture condenses out, but not much cooling occurs. Extended running might cause the gas to migrate to the condenser, leading to an LP trip if this unit has one. The LP switch might be colour coded blue, HP red.

The wiring diagram and unit look simple enough. It doesn't look like the compressor is speed controlled, but I do need to study th diagram a bit more.

If power has been getting to the compressor and it isn't running will likely kill it, but simple enough to check with a simple multimeter. Disconnect the power, pull off the connections on the CSR terminals. Then measure the resistances

Common Run - Lowest for this size compressor around 1-2 ohms

Common Start - quite a bit higher ~ 5-7 ohms

Run - Start - higher agin and also CR + CS so 6 - 9 ohms

I suspect the power simply isn't getting through to the compressor.

A final check is to see if you have gas inside the unit. This is a really basic check - remove one of the schraeder charge valve caps and briefly depress the valve pin and see if it hisses fairly hard. With the unit off and assuming your ambient temperature is around 25oC it should be about 8 bar with R417A, so you will definitely know if there is a decent as charge. If you have a gauge with schraeder lifter then you can accurately measure the pressure within.

R417A is also sold as Isceon MO59 (Du Pont now Chemours).

If you can undertake these checks then let me know what you find. Fault finding by forum is not easy, so if you PM me I can give you my direct contact details.

You will find a decent explanation of how a single phase compressor works here ...

https://www.dropbox.com/s/qhkkox4xfaoqc5o/ThermaCom Field Compressor Guide.pdf?dl=0

Also a simple check is the overload klixon on top of the compressor just above the terminals in the diagram. Check for continuity (0 ohms) across the two wires. If these do operate sometimes a rap with a screw driver handle will reset the bimetal strip inside the thing.

 

[jfm]

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:

 

[jimmy_the_builder]

SCR on the compressor refers to the connections Start Common and Run. The start capacitor connects the power from the run terminal and causes a phase shift to make the compressor turn.

If you have power at the compressor it should run.

To have the thing in permanent cooling I would suggest the wire from the controller to the reversing valve 2nd from right should be disconnected, but this won't stop the compressor running. A stuck reversing valve can cause LP trips, and a light tap with a mallet might release it.

I would check to see if you have both HP and LP switches (not shown in the photos) and see if these have small rubber dimples on the side opposite the pressure connection. If so press these and see if the thing starts.

Running in dehum mode simply runs in cooling mode at low fan power, causing a cold cooling coil with low fan speed, so the moisture condenses out, but not much cooling occurs. Extended running might cause the gas to migrate to the condenser, leading to an LP trip if this unit has one. The LP switch might be colour coded blue, HP red.

The wiring diagram and unit look simple enough. It doesn't look like the compressor is speed controlled, but I do need to study th diagram a bit more.

If power has been getting to the compressor and it isn't running will likely kill it, but simple enough to check with a simple multimeter. Disconnect the power, pull off the connections on the CSR terminals. Then measure the resistances

Common Run - Lowest for this size compressor around 1-2 ohms

Common Start - quite a bit higher ~ 5-7 ohms

Run - Start - higher agin and also CR + CS so 6 - 9 ohms

I suspect the power simply isn't getting through to the compressor.

A final check is to see if you have gas inside the unit. This is a really basic check - remove one of the schraeder charge valve caps and briefly depress the valve pin and see if it hisses fairly hard. With the unit off and assuming your ambient temperature is around 25oC it should be about 8 bar with R417A, so you will definitely know if there is a decent as charge. If you have a gauge with schraeder lifter then you can accurately measure the pressure within.

R417A is also sold as Isceon MO59 (Du Pont now Chemours).

If you can undertake these checks then let me know what you find. Fault finding by forum is not easy, so if you PM me I can give you my direct contact details.

You will find a decent explanation of how a single phase compressor works here ...

https://www.dropbox.com/s/qhkkox4xfaoqc5o/ThermaCom Field Compressor Guide.pdf?dl=0

Also a simple check is the overload klixon on top of the compressor just above the terminals in the diagram. Check for continuity (0 ohms) across the two wires. If these do operate sometimes a rap with a screw driver handle will reset the bimetal strip inside the thing.

Wow. This is very helpful, thanks. (And especially thanks for talking all the considerable time necessary to write all this stuff up, really appreciated).

Resistance at the compressor, with everything disconnected:
S-C 4.9 ohms
R-C 2.4 ohms
S-R 7.1 ohms
(bear in mind these are readings taken on a cheapy Maplin multimeter)

With a voltmeter connected, what seems to be happening at start is that mains voltage briefly appears across R-C, and then disappears. At the same time, a smaller voltage (I saw maybe 15v ac) appears over S-C and similarly disappears. This cycle of attempting to start the compressor appears to repeat every 30-40s or so. (I stopped after 3-4 attempts).

I haven't found the HP switch - this is the pair of yellow wires that run prominently across the circuit board in the photo above - they disappear into the loom and I don't yet know where they emerge. Should I expect this switch to be in the vicinity of the aircon unit, or is it remotely located with the raw water pump?

There is no LP switch - it is shown as optional on the wiring diagram and on the circuit board the two connectors to the LP switch are just shorted with a white wire loop.

A brief press of the 'suction' valve produced a hiss.

The 'klixon' on the compressor shows zero ohms.

So the one thing I can't definitively prove is the HP switch. I am hunting for that now.

Again, many thanks for the guidance.

 

[jimmy_the_builder]

Found the HP switch - sorry about poor photo quality, it's a bit inaccessible:

It's the green thing in centre of pic, yellow wires, red dot in middle.

 

[jimmy_the_builder]

Found the HP switch - sorry about poor photo quality, it's a bit inaccessible:

It's the green thing in centre of pic, yellow wires, red dot in middle.

I can't feel any give when I press the red dimple. However, with the loom disconnected, this switch reads zero ohms.

 

[jimmy_the_builder]

Does the HP switch relate to the refrigerant pressure?

Is there a switch that relates to raw water flow? (Or would there be some other indication of no raw water flow? I'm going to get lots of 'I told you so's about this - but my raw water outlet is below the water line, so there's no visible (or audible...) tell tale. However with the pump running if I begin to close the outlet seacock you can hear the pump note change as it works harder against the reduced outlet size.

 

[jimmy_the_builder]

Final comment for now - in the start cycle, mains voltage appears on the compressor C-R terminals, but it seems to bog down immediately, the voltage falls to about 150v and then to zero.

Could the compressor be seized?

 

[Portofino]

Would not have thought so ,it would hum and buzz a bit and maybe warm up , plus comp will have been running when in dehumid mode -so unlikely ceased .
If its cutting out something is telling it .
Have you tapped reversing valve few times ,simultaneously starting it @ cold or heat .
If its jammed twixt two maybe comp is told to stop .needs to be fully one way or t,other to allow comp to start
That's what you are seeing I suspect
Your screen will tell you stuff like Lp low pressure etc so it's gotta be something that's NOT displayed normally -assuming the diagnostic function still works .

It's unlikely to be a raw water pump issue -comp starting -nope
Comp should work without water pump initially for a few mins ,then pump raw water turns on to start cooling the refrigerant . After it detects its ready to needcooling .Not necessarily both comp + pump come on together
Also put your hand on the raw water pump should vibrate when it comes on .

 

[jfm]

You'd get "hpa" error code on the cabin display panel if there was no raw water flow. Sounds like your pump is running ok - ref your close-the-seacock trick

If comp were seized I don't see why the volts across it would fall as you describe

Control board failure? (does happen)

 

[jimmy_the_builder]

Would not have thought so ,it would hum and buzz a bit and maybe warm up , plus comp will have been running when in dehumid mode -so unlikely ceased .
If its cutting out something is telling it .
Have you tapped reversing valve few times ,simultaneously starting it @ cold or heat .
If its jammed twixt two maybe comp is told to stop .needs to be fully one way or t,other to allow comp to start
That's what you are seeing I suspect
Your screen will tell you stuff like Lp low pressure etc so it's gotta be something that's NOT displayed normally -assuming the diagnostic function still works .

It's unlikely to be a raw water pump issue -comp starting -nope
Comp should work without water pump initially for a few mins ,then pump raw water turns on to start cooling the refrigerant . After it detects its ready to needcooling .Not necessarily both comp + pump come on together
Also put your hand on the raw water pump should vibrate when it comes on .

Yep have tried multiple starts in heat and cool; same behaviour. Similarly have tried multiple starts while tapping reverse cycle solenoid/shuttle valve. Again no change.

 

[jimmy_the_builder]

You'd get "hpa" error code on the cabin display panel if there was no raw water flow. Sounds like your pump is running ok - ref your close-the-seacock trick

If comp were seized I don't see why the volts across it would fall as you describe

Control board failure? (does happen)

Hmm. How about failure of start capacitor? Could that explain the low volts observed on the start circuit?

 

[superheat6k]

The compressor is trying to start then. Do you have an amp clamp ? Knowing what amps the run winding is passing (R-C) would be useful, but as there is no voltage on the Start winding (S-C) is would go for either the run capacitor, or if there is one the start cap and its relay.

If you can get a 10 MFD Cap and hook it across the wires going to C&H on true capacitor and see it that starts it.

The HP switch isn't the issue. I expect if it trips the red dot will pop up. If it were tripped the compressor will not try to start.

You can hot wire a compressor with mains Live via a switch onto the common with neutral connection to Run, and also to Start via a 10MFD capacitor, and with a 100 MFD wired with it in parallel but if it doesn't run immediately disconnect it. If you are not familiar and confident with 240v circuits then do not do this. But this will prove if the compressor works and therefore the problem is something else.

In normal start mode the 100 MFD start cap would be disconnected after a few seconds.

So have you a separate Start capacitor ?

I noticed another component top right on the wiring diagram that looks like a start capacitor switching relay, and a thing below it with triangular shaped ends. These could be a start relay and start capacitor.

Both Start (~100MFD) and Run (~10MFD) Caps connect in parallel between the Run and Start, the purpose of the relay is to turn off the start cap only as the compressor starts running, the Run caps stays in circuit the whole time. This thread isn't the place to explain why, beyond the fact that higher capacitance causes a higher phase shift and hence greater start torque.

I notice also that the fan works, as the run cap also seems to provide the running start coil for the fan, suggesting the run cap is OK.

Be aware that tests of this nature can be terminal for the compressor, but as it might already be goosed I feel they are worthwhile checks.

DO NOT CONNECT POWER TO THE C-S TERMINALS WITHOUT POWER TO THE R-S, AND SUITABLE CAPACITORS WIRED IN. IF YOU DO THE WEAK START WINDING WILL TRY TO RUN THE COMPRESSOR AND IMMEDIATELY BURN OUT.

 

[jimmy_the_builder]

I do have an amp clamp - on the 'run' circuit the current draw is intiially 25A, falling to 20A, and then to zero. On the 'start' circuit the current draw is 1A, then zero.

From the wiring diagram, I think this must be the run capacitor:

And this is the component identified on the wiring diagram as 'assist start ptcr'. Is this a combined relay/capacitor?

I don't have any spare capacitors on board. Is there any way of testing the start component using a meter?

 

[superheat6k]

Ok so when you start the main run winding is pulling lock rotor current to try to get the compressor started. But there is virtually no current on the start winding. After a few seconds the current reduces to 20 the 0a. I suspect this is the klixon on top of the compressor opening to protect the winding. Bear in mind your max run current for the whole thing is just 4.7a, so if it is pulling 20 - 25 a something is going to get very hot.

Do not try to start the compressor too often because each time it try to start there is a heat build up within the windings, and this can cause a burn out. We reckon no more than 6 starts per hour, and do not leave the motor struggling to start. If it doesn't go straight away turn it off. Leave at least 5 minutes between each attempt and extend the gap the more you re-try.

I am still not sure if the device shown on the left side of your wiring diagram is a start relay, but anyway the run capacitor should be in circuit all the time with a small current say 0.5 a to maintain the rotary motion of the rotor. Remember the run capacitor still connects to the start winding, and this confuses people.

I would try a new capacitor. If there is a washing machine shop nearby you might be able to get a suitable run cap there.

Your capacitor is effectively two caps in one - one part to the compressor start winding the other to the fan.

Two separate caps will do the same thing. The black disc device is a hard starter, designed to increase the starting phase shift. I googled this and this confirmed this is a hard start device.

I would disconnect this and then try without it in circuit then again with a new run cap. I suggested ~ 10 MFD but see what is written on the side as I can't quite see the value (uF or MFD) in the photo.

Unless you have a high voltage megger it is difficult to test a capacitor. If you do with it set to 250v or 500v connect the leads across the terminals going to the compressor (disconnect from comp first) and charge with the meter for a few seconds. Then short it out with a screwdriver and if it works you should get a decent crack out of it. DON'T USE YOUR FINGERS FOR THIS TEST.

If you the cap won't take a charge it is u/s. This would be my first thing to change here.