R12 to R134a

[fireblade]

FIrst would like to say what a great forum,
This is my first entry, so sorry if i mess up !

ex Hotpoint engineer of 24 years, always done fridges/freezers,
but only the electrical side of things till last year for which i now involve myself in the refrigerant cycle.

Im converting a fridge/freezer that is R12 to R134a,
Thats a new R134a compressor and dryer.

The unit.. R12 specifies 280grams, not sure how much R134a to charge ????

Thanks for all info.

fireblade

[Abe]

One way is to charge it till the low pressure pipe starts sweating....Thats the line back to the compressor.

Ensure no liquid gets back into the compressor, watch the "ice line"

Will take a little time to charge it correctly.........called " critical charge"

[Andy W]

Use R49 instead and reduce charge by 8 - 10%.

[slingblade]

A good starting point here is to charge 280g of 134a. if it goes BANG you were wrong. i dont think this is at all likely though.

[Toolman]

Just use same charge as the "OLD GAS " if the compressor is a ball of ice after its down to temp you have overcharged it and adjust accordingly .

[fireblade]

Thanks for the info guys
will let u know the outcome

[NoNickName]

Please use MP39 or similar.

[John Wood]

I reckon you will need about 250g of R134a

[The MG Pony]

you do realize that you need to change the oil to POE right?

[Langer]

you do realize that you need to change the oil to POE right?

Sure he's changing the compressor!

new compressor comes with new oil.

[Andy W]

Sure he's changing the compressor!

new compressor comes with new oil.

Thats fine as long as it is a R134a compressor as there are still some R12 compressors for sale, electrolux for one still sell them.

[Langer]

Thats fine as long as it is a R134a compressor as there are still some R12 compressors for sale, electrolux for one still sell them.

If he's changing out an R12 pot for a 134a, there's no
need to do anything else. Just fit the 134a pot in, you're not going to flush out a Domestic and change the cappillary line.

[Andy W]

If he's changing out an R12 pot for a 134a, there's no
need to do anything else. Just fit the 134a pot in, you're not going to flush out a Domestic and change the cappillary line.

As a precaution I would blow the system through with OFN before fitting the new compressor and filter drier.

[Langer]

As a precaution I would blow the system through with OFN before fitting the new compressor and filter drier.

True, but i woundnt spend too much time on it though.

'Tis only a domestic after all.

[Andy W]

True, but i woundnt spend too much time on it though.

'Tis only a domestic after all.

Doesn't take long, I use a VAX 4 access fitting attached to a piece of 1/4" ID plastic hose, this is my quick coupler for blowing through pipe work with out having to solder stubs on first.

[The MG Pony]

If a job is worth doing it is worth doing right, if not then why do it at all?