Use of Dye in a Refrigeration System

[Mayball]

During my work on pleasure boat refrigerators and air conditioners, I occasionally inject dye into some of the systems to locate elusive leaks. Lately, I have used Mastercool Fluorescent Dye. On a recent job with a small cap tube refrigeration system, I had evidence of insufficient cooling by the keel cooler condenser (climbing discharge pressure before a full charge of R-134a had been added). The keel cooler is a small bronze plate, with a cupronickel loop cast in it, located on the outside of the hull and connected to the copper discharge and liquid lines through a sealed thru hull. Thinking the cooler was too small to function in the warm Mexico waters, where I work, I contacted the manufacturer.

The manufacturer said the keel cooler had been tested in water warmer than one would encounter anywhere and that the cause of the problem was almost certainly the use of dye or stop leak added to the system. I had not added anything to that system but pure R-134a and had vacuumed the system well before that. I replied that I could see where stop leak could affect heat transfer, but not dye which resides in the oil. He replied "please take my word for it that it is not simply a matter of the keel cooler tubes have been coated with some foreign material".

Has anyone come across evidence that refrigerant dye adversely affects heat transfer in a system?

[Jeremy Martin]

I've used Yellow Jacket dye multiple times and never had a problem. 'Course, that's on mostly A/C and walk-in cooler/freezer systems where heat transfer is probably not as critical.

You sure you don't have noncondensable gases running up the head pressure? Did you bleed the air out of your hoses before you added refrigerant?

[Mayball]

I did vacuum the system before charging, and my hoses were included in the system vacuumed.

[nike123]

Heat transfer of condenser can be judged by condenser approach value!
First make sure that there is no incondensable gases inside, than make sure that water flow is sufficient and in right direction.
Than take full set of measurements and it will be visible.

[monkey spanners]

Would think a blocked cap tube more likely than the dye insulating the inside of the condenser.

[Mayball]

nike123, With a keel cooler, there is no water flow unless the boat is underway, but the condenser should be able to function adequately when the boat is at anchor or tied up to the dock.
monkey spanner, With a blocked cap tube, the compressor will shut down because the electronic controller will sense too high a current draw. However, if the cap tube is only restricted, it could explain the problem I am having. Frankly, I think the keel cooler is too small for the warm Mexican waters, and the manufacturer rep is just blowing smoke.