R290 top up

Hi guys new to this site,
Looking for advice on r290 , I've never worked on this before in my many years I've been in the trade, but came across a fosters fridge the other day that was sat at 28 degrees, everything was working (evap/cond fans, comp etc) pressures where -11inhg low side and 50psi high side , after researching what the running pressures should be I've come to the conclusion it's low on gas, I've arranged to pressure test and recharge but the drier is in the most horrendous place as is almost impossible to replace and braze with out burning the side panel which cannot be removed,
Would anyone just Risk not changing the drier ? And please correct me if any of my assumptions on the pressures are wrong
Thanks

Depending on the fridge model it can be possible to remove the condensing section to make repairs.

Unfortunetly this is not one of those models the condensor and comp are sat on the top and the drier is sandwiched between the condensor and the side pan of the unit

Maybe advisable to get a basic 1/2 HC course under your belt to ensure your up on the safety side of these refrigerants. A1 rated evacuation pump and recovery machines required.
R290, as with other HC known to readily mix with oil which moves through the system freely. On integral type systems such as a Foster unit, blocked drivers are not un common I believe.
I would cut out the drier and blow through the system with OFN as part of the repair process to eliminate a blocked drier.
As with HFC Foster units some times the 1/4 pipe, drier , capillary assembly can be manipulated into a more easily accessible position to cut out the drier, and a new item soldered in.
For safety purge through entire system with OFN to remove all traces of R290 prior to undertaking any hot work.

Condensors block with dirt then block capillarys prone to this fault we have had same issues with access either reposition drier or use lock rings we tend to use lock rings more on the flammable gas as I like my eyebrows !

Thanks for your helpful reply Yes I think I'm going to arrange a HC course for future reference, but for the time being I will wheel the fridge outside and let the gas go into the atmosphere then chop out the drier and try re position it, Inwill have to make do with my standard vacuum pump this time (hoping that is safe to use)

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There is a lot of hype and fear regarding HC's.
Treated with respect it is no more risk to you than
the older R22 refrigerants.

I would highly recommend doing the HC course minimum
one day but recommended if you want to buy the stuff.

Venting in the carpark is an option but I would recomend
purging with Oxygen Free Nitrogen (OFN) while you attempt
to braze in the new dryer.

Actually you need to purge OFN and vac the thing 3 times before
attempting to remove the dryer (if you unbraze it).

You do not have to buy a new vac pump, what you do need though
is an extension lead and only ever switch it on the wall 3 mtr away.

Use a dryer with a schrader charging stub pre-fixed into it, that way
you can measure the high and low side.

Rob

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