404a freezer

[spst460v]

hey people i do commercial hvac not refrigeration, i could really use some good advice on this. i have a hobart freezer (df2) reach-in type. it quit cooling and i found that the drier was restricted so i replaced it and recharged the unit by weigh in specs on the data plate. on start up the comp did ok, but my pressures were 220-5 w/ a 92 outdoor ambient and a 85 cabinet temp, the press seems a little low to me but it should have a proper charge i charged it per data plate. i let it run for about 20-30 min and noticed the pressures so i examined again, and found frost at the inlet to the evap coil but the rest of the coil was not even cool, is there another restriction that i missed? the inside temp never moved either. i shut the system down and came back and restarted it and found the comp stayed in the start cycle for around 20-30 sec. with lra's @33.6 and kicked over to run cycle w/rla's @ about 6.8. what he heck did i do wrong? i blew nitrogen through the system while brazing, had a deep vac. charge par data plate seems good. what's up?

[R12rules]

Assuming you used the very same sized drier aas the factory one ... so the charge is flowing evenly ... I see you musta had a pluged condensor. Pluged with dirt on the outside, I mean.
A dirty condensor on these four o four units heats the poe oil to where it burns a sludge on the inside of the cap tube. And this restricts it forever.
Forever!
So you must replace your cap tube now. Then repeat what you already did.
And it wouldnt hurt a bit if you did an oil change on your compressor, while your at it.

Jus measure what comes out and pour in new poe of the same amount.

I tip over the compressor and use nitrogen to pressure it out then use the vac pump to suck back in the new oil.

The only other thing you might do is try cuttin goff six inches of your entry cap tube and then putting the system back into operatin. Sometimes this works. But most of the time ... it doesnt.


If you were spending this kind of time on a cryogenic system ... this is small money we are talkin about here.
But since this is a small fractional horsepower fridge ... your gonna hafta make each and every footstep count.

Everyone here has been in your shoes and they did exactely what you just did.
When we worked with real freons, we never had to deal with crap like this. It just didnt happen.
But since dupont has become so high and mighty as to fool even our congress and to even delude our industry leaders, cough, cough .... we are stuck playing patsy for these chemical conglomerates!
And we're the one's who have to spend all this time and energy figuring out the idiosinkracies of these blended blends!!! AUGH!!!

The end user isnt always happy with us nor the bill when we are finished and the unit is once again running.


anyway ... try this and let us know how it turns out.

inquiring minds want to know. :D