Recharging Danfoss BD35

[Boatwright]

Any advice on correct low-side pressure after recharging an Isotherm BD35 Compact system. We have the small oval evaporator in a combined refrig / freezer with a circulating fan.

After an unfortunate defrosting with a chef's knife accident last season, I recommend hot water to loosen up the frost, and promise to be more patient in the future with the thin gauge aluminum. We have the system sealed up, vacuumed, and leak tested. After recharging using the 5 second squirt method with the box cold and the compressor running we are seeing low side @ 1 to 4 PSIG. Surface temp of the evaporator is 10 - 15 deg F.

We are in the ball-park with the liquid line on the low side is about 6" from the evaporator. However, this unit originally came precharged and I am wondering what the correct factory spec low-side pressure ranges should be.

[Bowdrie]

Originally Posted by Boatwright

Any advice on correct low-side pressure after recharging an Isotherm BD35 Compact system. We have the small oval evaporator in a combined refrig / freezer with a circulating fan.

After an unfortunate defrosting with a chef's knife accident last season, I recommend hot water to loosen up the frost, and promise to be more patient in the future with the thin gauge aluminum. We have the system sealed up, vacuumed, and leak tested. After recharging using the 5 second squirt method with the box cold and the compressor running we are seeing low side @ 1 to 4 PSIG. Surface temp of the evaporator is 10 - 15 deg F.

We are in the ball-park with the liquid line on the low side is about 6" from the evaporator. However, this unit originally came precharged and I am wondering what the correct factory spec low-side pressure ranges should be.

I can't off hand give you the factory specs for your particular compressor/evaporator combination.
When I had to recharge the 12V cap-tube evaporator units without knowing the specs I went for ~3>5 lbs on the low side.
Your results for pressure and frost-back show that you're well within the ballpark, probably in the infield.
Because absolute pressures will vary with temp the factory specs for pressure(s) would be at certain temps.
Most often a charge for these types of units would be specified as a certain number of ounces/grams by weight.
But when combinations of compressors/evaporators get mixed all is out the window and that's when the tech has to "play" with pressure/frost-back.
It sounds like you're doing ok.

[sailormed]

Boatsright:”After an unfortunate defrosting with a chef's knife accident last season, I recommend hot water to loosen up the frost...”

No meddling with hot water. Just put a fan in front of the open refrigerator, if possible remove or open the ice cube compartment. In less then 30 minutes all the frost can be removed, the evaporator plate cleaned and the fridge is back in business. Most boats have 12V fans installed, use a removable one, ours have clips to position the fan where needed.