SubZero 532

[air2spare]

has bad compressor on the freezer side and has R12. what are you guys using for a drop-in on this small stuff? I have some 409a sitting around

[skorepeo]

Low-Medium Temperature Refrigeration (R-12 type)


Ashrae #-----------components-----------charging

(trade Name)--------(weight %)----------(%original)


R-22-------------------pure----------------N/A


R-134a-----------------pure--------------- 90%


R-401A--------------22/152a/124-----------80-85%

(MP 39)--------------(53/13/34)


R-401B--------------22/152a/124-----------80-85%

(MP 66)--------------(61/11/28)


R-409A--------------22/124/142b-----------80-85%

(FX 56)--------------(60/25/15)


Overall Concerns: Match R-12 evaporator conditions (slightly higher discharge pressures OK).
Oil return must be addressed. Temperature glide not a problem in most applications.
Retrofit Recommendations (in order of preference based on performance/ease of use):
R-409A Better at lower temperatures, maintains performance, higher discharge T and P.
R-414B Better at warmer temperatures, lower discharge temp than 409A.
R-401A Good overall performance, need AB oil below 30F coil temps.
R-416A Biggest change in properties, poor low temp performance
R-406A Very similar to R-414B.
Freeze 12, Freezone, RB 276: Similar to 416A (134a based, not good in low temp)




Ashrae #-----------components-----------charging

(trade Name)--------(weight %)----------(%original)


R-414B-----------22/600a/124/142b--------80-85%

(HOT SHOT)----------(60/25/15)


R-416A-------------134a/124/600 ---------90-95%

(FRIGC FR12)---------(59/39/2)

Overall Concerns: Higher application temps will drive up head pressure and discharge temp.
These blends will lessen the abuse on the system but cost some capacity. Retrofit
Recommendations preference based on performance/ease of use):
R-414B, 416A Lower, or no, R-22 cuts down on discharge temperature/pressure.
R-401A, R-401B, R-409A for R-12 or R-500 air conditioning (direct expansion systems)


General Retrofit Procedure: Reciprocating AC and Refrigeration Systems
1. If the system is able to run – collect system data and operating conditions prior to retrofit.
2. Recover the R-12 from the entire system.
3. Perform any maintenance, repair or component replacements, and change filter/driers. If
needed (for low temperatures) remove mineral oil from the system and replace with an
equivalent amount of alkylbenzene oil.
4. Evacuate the system to manufacturer’s specifications.
5. Charge the system with the proper amount of the blend (usually 80% to 85% of the original
R-12 charge by weight). Be sure to remove liquid refrigerant from the cylinder to get the
proper composition (but flash the refrigerant before feeding into a running system).
6. Operate the system and record new system operation data. Make adjustments to controls
as needed to ensure proper operation.
7. Label the system with the new refrigerant and lubricant type.
Most Common Areas that Require Adjustment or Attention:
· TXV valve adjustment / superheat setting (use Vapor side of PT chart)
· Pressure controls (cut in / cut out)
· Pressure related switches or controls – difference from R-12 pressures
· Irregular frost formation with high glide blends
· High discharge pressure or temperature, high amps in high ambient temperature
conditions (abuse of compressor)

[air2spare]

I usually never do these appliance types but I have a good customer that asked to to do it so thanks again

[air2spare]

so AB oil it is then