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R438A substitute for R410A?

metlmunchr

Well-known member
Joined
Sep 10, 2011
Messages
1,280
A neighbor bought a new 6K btu GE window unit a couple years ago. Didn't use it until this summer and found it doesn't cool. One year warranty was already out so she bought a new one and asked if I wanted the old one rather than throwing it away, so I took it.

It appears to have lost the charge, or perhaps was never charged originally. I'll add a service port in the suction line to check for leaks and repair f there's a leak in a line. Coil leak is obvious junk.

To the question...... Does anyone know a reason why the unit can't be recharged with one of the R22 drop ins like 438a or 407c rather than the original 410a? Reason being I have partial drums of both drop ins but don't have any 410a. 2# cylinder of 410a is available for about $140, so that ain't happening to rescue a window unit.

Both drop ins are compatible with POE oil, and the mass flow rate per btu is near identical for 410a and both drop ins. The vapor enthalpy at a 40°F coil temp is a bit higher for 410a which would predict some loss of capacity with the substitute refrigerant but that's not a concern. Anyone know of anything else that would prevent the unit functioning? The goal is to get it working without spending any money, and then give it to one of the many elderly people in the area who can't afford a window unit.
 
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bonneyman

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Joined
Apr 22, 2010
Messages
8,855
Location
Desert SW
Since you got it for free just give it a whirl. Worst that could happen is the seals and windings in the compressor don't like the new freon/oil mixture and they fail. But you won't be out anything really.

Of course run it for a good week or so before you donate it to an older couple (very nice of you to think that!) just as an added check that it'll work.
 

NOEYEZ

Well-known member
Joined
Jul 1, 2022
Messages
48
A neighbor bought a new 6K btu GE window unit a couple years ago. Didn't use it until this summer and found it doesn't cool. One year warranty was already out so she bought a new one and asked if I wanted the old one rather than throwing it away, so I took it.

It appears to have lost the charge, or perhaps was never charged originally. I'll add a service port in the suction line to check for leaks and repair f there's a leak in a line. Coil leak is obvious junk.

To the question...... Does anyone know a reason why the unit can't be recharged with one of the R22 drop ins like 438a or 407c rather than the original 410a? Reason being I have partial drums of both drop ins but don't have any 410a. 2# cylinder of 410a is available for about $140, so that ain't happening to rescue a window unit.

Both drop ins are compatible with POE oil, and the mass flow rate per btu is near identical for 410a and both drop ins. The vapor enthalpy at a 40°F coil temp is a bit higher for 410a which would predict some loss of capacity with the substitute refrigerant but that's not a concern. Anyone know of anything else that would prevent the unit functioning? The goal is to get it working without spending any money, and then give it to one of the many elderly people in the area who can't afford a window unit.
It will work fine......pressure test first and repair any leaks...forget it if leak is fouind in the evap or condenser.....if it still has some pressure just try to pull a vacuum on the system first....this should boil off any water that may have entered the system from the atmosphere.....then use your 438a braking vacuum with refrig. first.....Don't allow any air to enter the system.....this unit probably holds just a few ounces of juice....don't want any air to enter and take up some refrigerant space........
Good luck!
 
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fitter30

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Joined
Jun 23, 2019
Messages
2,992
Location
Peace Valley,mo
410 -438 they don't run at the same pressures, compressors have different pumping capacity, expansion devices different design and R 22 uses mineral oil 410 poe oil their not compatible. Need anymore more reasons not to use the correct refrigerant. If you would decide to purchase refrigerant get one with stop leak. That small of leak would require a very good electronic leak detector with 500 lbs nitrogen pressure with refrigerant to find it.
 
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NOEYEZ

Well-known member
Joined
Jul 1, 2022
Messages
48
410 -438 they don't run at the same pressures, compressors have different pumping capacity, expansion devices different design and R 22 uses mineral oil 410 poe oil their not compatible. Need anymore more reasons not to use the correct refrigerant. If you would decide to purchase refrigerant get one with stop leak. That small of leak would require a very good electronic leak detector with 500 lbs nitrogen pressure with refrigerant to find it.
Best info up to date.....
 
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