Adding Freon to Isotherm ASU 3751Refridgeration unit

[rajhnsn]

I replaced the thru hull under the galley sink this past winter. The thru hull acts as a water cooling system for the refrigerant for the Isotherm ASU 3751 condenser. The tubes that connect the condenser to the thru hull have "quick connect" fittings but they screw together. When I took them apart I heard a hissing sound, presumably the freon leaking out. Now that it is all back together the cold plate does not get cold. Does anyone know how to add freon to this unit and how much to add?

 

[SEMPERAVANTI41]

You are going to have to evacuate the system, which may require the installation of a service valve (if not already present). I would contact Isotherm to get the exact quantity of freon required and the type. My understanding is in a small system like this the charge is critical for proper operation.

 

[Marmalade]

I had this issue with a brand-new Isotherm Compact 2013, and reached-out to Isotherm/IndelWebasto and this is what they said to do. Worked perfectly, just added a little at a time, has worked fine 2+year now.

Email text and attachment from Isotherm below. YMMV

"Regular R134A from an auto parts store is fine, I have customers use this all the time.
You will have to find an adaptor for the fill port, as the car use a different size, you could find it on a refrigeration/air conditioning store.
The service port is a standard ¼” SAE male flare fitting with a Schrader valve, see instruction attached that could help.

Thanks

Operations and Technical Manager
OEM Sales
Isotherm Marine Refrigeration"

 

[rajhnsn]

This is exactly what I need. I'll let you know how I make out. Thank you very much.

 

[Crusty Ol Salt]

Just remember too much is just as bad as too little

 

[deander]

That's very good to know. Where and how do you T in a fill port?
I have a new unit to install (Isotherm 3751) and was wondering about the thru hull. I have a 1979 Pacific Seacraft Orion. The galley sink drains through a 1 1/2" groco bonze ball valve with a flange with two bolts and backing plate. Seems like a more secure arangement than the heat exchanger thru hull from Isotherm with the ball valve above that. Are you happy with the thru hull from Isotherm with just the large nut to tighten it down tight?