Adding 507a to 404a-any problems?

[TJ D]

Hi all, I need one of our reefer pros to weigh in, if you don't mind.


I might need to add just a touch of refrigerant to my 404a system, and the local guy here in Spain insists that 507a is totally compatible, no worries at all to top up with it. I know the composition's nearly the same, but I'm reluctant to add anything other than 404.


Anybody got a definite answer on this one?



Thanks much, TJ

[TJ D]

bump...

[LeaseOnLife]

here you find the ingredients for each: R404a has a a tiny bit R134A, R507 does not. Will that make a difference, likely not:


R404A / R507 - Friedrichs Kältemittel - Friedrichs Kältemittel


Would the cost to evacuate, recycle and fill with R507 be too much? Then you know what you have, and not some unknown mixture.

[OzePete]

Hi TJ, All components of a refrigeration system are engineered to suit the various factors relative to the chosen refrigerant. Different refrigerants may differ only a little and often will work but they are different and there may be long term consequences if used.

I would also suggest leak testing to find out why the system is short, repair any leak, replace the filter dryer with a type 030 or 050 if possible, evacuate and regas with R404a.
Then you can relax knowing your system is operating as intended.

Cheers OzePete Ozefridge | 12 Volt Refrigeration Systems

[Richard Kollmann]

Originally Posted by TJ D

Hi all, I need one of our reefer pros to weigh in, if you don't mind.


I might need to add just a touch of refrigerant to my 404a system, and the local guy here in Spain insists that 507a is totally compatible, no worries at all to top up with it. I know the composition's nearly the same, but I'm reluctant to add anything other than 404.


Anybody got a definite answer on this one?



Thanks much, TJ

My solution is more practical in that the two refrigerants are comparable having only a slight change in temperature. Purge servicing equipment with 507a and add the correct amount of 507a refrigerant. If system"s refrigerant loss of more than 10% results in in the next six months then I would find and correct the leak and dehydrate before adding refrigerant again.

[TJ D]

You guys are the best, as always. Thanks for the advice, guys. I'm not actually sure that I have lost any refrigerant-it looks more like an intermittently failing control module at this point-this on a system that was installed in March and has only seen about 40 days of actual use since installation.


I located a module here locally, and will install a new one today, and see what happens.



The saga of the freezer here on Rocket Science has really morphed into a bit of a black comedy at this point, I'm afraid.


Normally, I wouldn't even care that much, but we've got a transatlantic coming up shortly, and we'd really like to have the freezer working reliably for that.


Hope springs eternal.

[OzePete]

TJ, Usually a failing module dies permanently, rarely do they act up intermittently.

You may simply have a bad case of the most common problem that DC fridges suffer from... failing power supply.

Suggest you check the supply voltage at the module. Check with a multi-meter both before it starts, when it starts and while running. (Usually the top two terminals on the module) If voltage dips to less than say 11.00 VDC, you may have a good fridge unit and bad power supply! (Battery, supply wiring etc.)

Cheers OzePete

[TJ D]

Originally Posted by OzePete

TJ, Usually a failing module dies permanently, rarely do they act up intermittently.

You may simply have a bad case of the most common problem that DC fridges suffer from... failing power supply.

Suggest you check the supply voltage at the module. Check with a multi-meter both before it starts, when it starts and while running. (Usually the top two terminals on the module) If voltage dips to less than say 11.00 VDC, you may have a good fridge unit and bad power supply! (Battery, supply wiring etc.)

Cheers OzePete

Yup, that was job 1. All's good on power. We're currently dockside, 13.1 at batteries, 13.1 when idle right at the unit, goes to 12.85 when both units are running. We ran AWG 6 to the units, wire sizing's good, connections are good.



That's not it...


It was also my understanding that modules either work or don't, but Seafrost said that they've heard of some intermittent failures, failing to start more and more often until it finally dies completely.


What we're seeing is a 'motor start error' code from the unit, which can mean 3 things:

1. Overcharged-I think that's not possible, we didn't add any refrigerant.
2. Trying to start a warm system-it happens when cold too.

3. Module failure.



Really, the only thing that fits here is a failing module, even though it makes little sense to me.



I'm sure open to ideas here, though.

[TJ D]

Well, we installed a new module, and we are still getting the motor start failure error. So, it's apparently not the module.


I can't imagine that I've got an overcharge situation happening, as we never added any gas, and the new unit was shipped with the correct charge.



I can't see any connection between temperature and when the compressor will and won't start, it just seems to try and try and then eventually it does kick on and work fine.



I really wonder what the heck is happening here.

[Richard Kollmann]

One thing for sure is motor start error is not an indication of loss of refrigerant. With error codes of three flashes or more it is difficult to tell whether it is module or excessive refrigerant pressure. If system was not running for more than a few days and ambient temperature higher than normal then an overload code is possible especially with this refrigerant.

The two things I would try first is check to see if ground wire from module to battery connections are good.
Second I would use ice to bring temperature down inside freezer box and place a plastic bag of ice on top of compressor for several hours before trying to power up system.

With these Blended refrigerants letting out refrigerant is never a good idea to correct an overload condition. The only way to rule out module is by trying a new module. It is always a good idea to carry a spare module anyway on a blue water cruising boat.

[OzePete]

Hi TJ,

If you are sure that there is no voltage drop at the top two module terminals upon start up, try these things:
1: Disconnect fan wires from module and try.
2: Add a wire link between the bottom and third from bottom terminals on the module and try.

BTW did any additional refrigerant get added?
And when it eventually does start, do you notice any frost / cold sweating momentarily on the suction pipe where it connects to the compressor?

Cheers OzePete

[TJ D]

Originally Posted by OzePete

Hi TJ,

If you are sure that there is no voltage drop at the top two module terminals upon start up, try these things:
1: Disconnect fan wires from module and try.
2: Add a wire link between the bottom and third from bottom terminals on the module and try.

BTW did any additional refrigerant get added?
And when it eventually does start, do you notice any frost / cold sweating momentarily on the suction pipe where it connects to the compressor?

Cheers OzePete

Pete, I was at the fuel dock when it finally started, but once it starts-operation is normal. Both plates frosted, temp drop about what I'd expect it to be in this awful heat, etc.


The damned thing just won't start up until it's tried a couple hundred times, it seems. Box/plate temp doesn't seem to have any bearing on this either.



No refrigerant has been added.



Right now, I've got a tech on the way, and we're going to take a look at pressures, etc. He thinks that the system may be a little overcharged despite none having been added. Since we had the same thing with a new module, it may well be the case.



Is the jumper wire something that I can do as a semi-permanent fix?







A

[TJ D]

[QUOTE=Richard Kollmann;2703634]One thing for sure is motor start error is not an indication of loss of refrigerant. With error codes of three flashes or more it is difficult to tell whether it is module or excessive refrigerant pressure. If system was not running for more than a few days and ambient temperature higher than normal then an overload code is possible especially with this refrigerant.

The two things I would try first is check to see if ground wire from module to battery connections are good.
Second I would use ice to bring temperature down inside freezer box and place a plastic bag of ice on top of compressor for several hours before trying to power up system.

With these Blended refrigerants letting out refrigerant is never a good idea to correct an overload condition. The only way to rule out module is by trying a new module. It is always a good idea to carry a spare module anyway on a blue water cruising boat.




































i/QUOTE]


Hi Richard, we will investigate the wiring a little more. It is doing this with a seriously cold box too. I ran it down to a plate temp of about -12f, and it still won't start up until after a long session of trying.



Operation is normal, as far as I can tell, once it actually starts.



We installed a brand new module a couple of hours ago, and there is no change to the problem.



Thanks for all the help, much appreciated.

[OzePete]

Originally Posted by TJ D

Pete, I was at the fuel dock when it finally started, but once it starts-operation is normal. Both plates frosted, temp drop about what I'd expect it to be in this awful heat, etc.


The damned thing just won't start up until it's tried a couple hundred times, it seems. Box/plate temp doesn't seem to have any bearing on this either.



No refrigerant has been added.



Right now, I've got a tech on the way, and we're going to take a look at pressures, etc. He thinks that the system may be a little overcharged despite none having been added. Since we had the same thing with a new module, it may well be the case.



Is the jumper wire something that I can do as a semi-permanent fix?







A

TJ, From what you have described and specially that you have replaced the module and confirmed that the DC power supply is not dropping off at start up we can assume that the module is not the problem and the supply voltage is adequate.

REFRIGERANT: If the system is over charged to the point of restricting start ability, there would be frosting on the suction line when running and as the evaporator temperature lowers. (If it is a capillary system). If no suction line frosting occurs when the plates are very cold then it is not overcharged.

Another possibility gas wise is if the refrigeration unit is located much lower than the freezer cabinet and in a relatively cooler position.
Also check by feel the temperature of the compressor after it has completed a long run period. It should be quite warm, not cool / cold. (Refrigerant will migrate and condense into liquid inside the compressor during off periods if the compressor is relatively cold when off. This will hydraulically restrict motor startup which relates to what you report.)

ELECTRICAL: The suggested link of the thermostat terminals will eliminate any issues regarding the thermostat. (unlikely but possible) and removing the fan and trying is to eliminate the possibility of the compressor's module being corrupted from the fan's processor. (also rare but does happen)

The other rare issue could be high transient voltage shutting down the module. To check this remove everything from your battery supply terminals except the fridge unit and test run. (Again very rare but we are hitting the bottom of the barrel here!!!!)

Cheers OzePete

[Richard Kollmann]

The tech will not have much success checking pressure if he can not get the compressor to run. It would help to know the compressor model and module part model. Most of Seafrost small compressor systems have adjustable low pressure regulators has anyone tampered with this valve's adjustment?

It is important to know at what point of time does this compressor start rejection problem begin, First start up or after thermostat cycled unit off and tried to restart again. Off cycle time is also important to allow low pressure regulator to bleed down high pressure. Hopefully the off cycle is at least five minutes as this type flow control is not always internally equalized.