Recharging freezer

[Hedges]

Some years ago my upright freezer stopped keeping things cold enough Recently measured about 32 degrees F, and it varies with ambient. We started calling it the "Deep Fridge".
It takes the same R134A as my car, 6 oz., so I decided to try refilling it.



I have a refrigeration manifold and pump from Harbor Freight, so didn't buy a kit with hoses. I just bought the following piercing valve:

2 Pack BPV-31 Bullet Piercing Tap Valve Kits Compatible With 1/4" 5/16" 3/8" | eBay

Find many great new & used options and get the best deals for 2 Pack BPV-31 Bullet Piercing Tap Valve Kits Compatible With 1/4" 5/16" 3/8" at the best online prices at eBay! Free shipping for many products!

www.ebay.com

This one is "Chinco" brand. I've read reviews mentioning lesser makes with metal debris that didn't seal, and another might be the name brand.

Lately 12 oz. cans of R134A have been $20 + $10 deposit and Winchester Auto and Auto Zone. At O'Reilly it was $7 + $10 deposit (I guess they didn't get the memo.)

I have a small scale for selling recreational ... (um, never mind), which I put to use measuring weight of refrigerant can:



Based on later readings, I think my attempt to weight the can with hose attached had error.
I tried to evacuate the hose, but without a good valve at the can was unsuccessful so pressure purged it.
Anyway, after putting in a couple ounces, I monitored the freezer. It got down to 15 degrees F.

I tried more later, intending to get close to 6 oz. Don't know how low it had been.
I also tried measuring temperature of discharge and suction lines. Readily available suction line was too close to compressor, so above room temperature. So much for making this a science.

What remained in the can I put in my car, which I had only charged with a single can before. Careful weight indicated car got 8.3 oz.

Final weighting of empty can (3.42 oz.) showed contents had been 12.21 oz, so refrigerator got 3.91 oz (less whatever was lost purging hoses.)



Freezer now runs about 5 degrees F, saw 0 degrees once.

Seems like thermostat at warmest setting doesn't cycle off even at 5 degrees F, need to determine what range it is supposed to have. Possibly replace; that would let freezer run a bit warmer and not operate compressor constantly.

 

[Supervstech]

Thermostats are coil temp release type. Meaning they have a range of scale depending on the ambient to coil surface spread. If the warmest setting won’t shut off when box is at 5F, there may be insufficient refrigerant in the system to get an evaporator temp below the minimum setting.
those surface condenser models are terribly difficult to recharge… not to mention, there is a leak somewhere.

Did you have one or two hoses connected for charging?
Each hose can hold 3 oz… so, very little may have made it into the freezer.

 

[Hedges]

I had two hoses connected, middle one from manifold going to can and low side with gauge going to piercing valve.

What does "LS 140 PSIG" "HS 320 PSIG" on label mean?
I was seeing near vacuum on suction side with compressor running. So I doubt I left 3 oz + 3 oz in the hoses. And still put 8.3 oz in the car (and hoses.)

Thanks for the tip, maybe I should run a thermocouple to return side of evaporator, watch that while adding more?
What temperature should I look for (doing this in a 70 to 85 degree house)?

Leak somewhere maybe, but must be almost imperceptible as it has been limping along for years. Unless on low side, and that has stabilized at 0 PSIG?
The unit is going on 21 years old now.

Difficult how? I did it, but not sure how much I did. Suction was slow enough didn't form ice like recharging the car, and I simply warmed the can with my hands for the second shot.