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carrier 950mt
19-06-2016, 03:27 AM
I work for a truck dealership and many of our trucks have carrier 950mt units. We attempt to do the majority of repairs but we have no way of recovering the 404a. My question is this.. Am I able to convert an old R134a recovery machine to recover and charge the 404a? I can not seem to find any info on doing this conversion. Any help and suggestions would be appreciated. Thank you.

Rob White
19-06-2016, 10:58 AM
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As long as the machine is working, with no leaks it would be fine as it is.

As far as the recovery machine goes, it's not bothered what refrigerant you use with it
as long as it is within the pressure capabilities of the machine.

404 works slightly higher than 134 but as long as the safeties are ok, I see no
reason why you could not use it for 404.

If it is a mobile car / truck AC R134a machine they might have oil seperaters
on and things like that for recycling the refrigerant.

Just make sure it is working correctly and make sure it is safety protected
for the 404 and it should be fine with little or no modification.

Rob

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carrier 950mt
19-06-2016, 12:47 PM
Thanks Rob, So as long as everything is working properly, I should be able to just switch out the tanks and fittings? Would the scale be affected at all? I am fairly sure the 134a tanks were depleted before we put it off to the side. If so can I use the same tank or should I put in a empty 404 tank?

Rob White
19-06-2016, 01:19 PM
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The tanks (cylinders) would need to be completely empty and then vaccumed
dry / clean to ensure no air, moisture, contaminants and or other such rubbish is inside.

As for the cylinders there is no real reason why they would not be ok.

My only one concern would be the discharge hp switch setting.

On modern recovery machines they are set to trip in the high side at about
24 - 25 bar range (340 - 360 psi) but the 134 may be set lower, maybe
about 18 - 20 bar (250 -300 psi). This is not a problem but it might slow
the recovery down of the 404 and might cause issues in warm weather
because it would shut down on hp too soon.

It would be ok and perfectly safe, if anything the safety margin is better with
404 than with the 134 but for good optimum performance check out the highside cutout.

Weight scales should have no effect, your only weighing liquid and the scales don't know
the difference between any of the refrigerants.

As for the fittings, yes the car / truck AC fittings would need replacing for standard
fridge fittings but only on the connection end all the other fittings are fairly standard.

regards

Rob

Magoo
20-06-2016, 02:12 AM
Hi carrier.
further to what Rob advized, your recovery bottles should be certified tested and have releif valve at 400 psig. Fill rates dependent on vessel volume which will be stamped on vessel as WC /water content, fill to 70% of that volume by weight to be on the safe side. for what ever refrigerants weight per liter or US gallon.

Magoo
20-06-2016, 02:45 AM
Hi again carrier,
get your employer to splash out and supply a decent recovery unit, preferably and oil less compressor system, will not break the bank to purchase, names are Yellow Jacket, Appion and Rothenberg there are more available as well.