A/C tech ?

SS MAYFLOAT · Jun 27, 2008

Last weekend a friend of mine finally got his boat docked. He did his own A/C install. To install it, he had to cut the freon lines and rerouted them to be able to have the necessary space for the stuff to fit. I checked the system out and it looks okay, but he has problems. I know why, but he refuses to believe me.

When he got his lines all soldered in, he installed line tap valves (which I never use due to their ability to leak). He never evacuated the system. He was told by another pro that it was not necessary. Huh? I never heard that one. He then says that it works, but when it starts getting hot out, the amp draw goes sky high and trips his breaker. I told him it was because of all the non-condensables that is in the system and that it needs evacuated. Then he changes his story that his pro friend did the work.

I have never heard that you can successfully charge a system without pulling it into a vacuum. Has anyone else heard this? I have been trained that for a system to successfully be charged, a vacuum must be done. This just goes against all my training...........

I'll get him to log on later to see the responses......Thanks..........SS

TilliamWe · Jun 27, 2008

Re: A/C tech ?

SS, I wouldn't argue with you on this, so I'll ask a question.

If you can't sucessfully recharge a system without evacuating it, then how do those "do it yourself" refill kits work? I know you're gonna say "they don't work", but I know of a 1984 Ford Bronco II that it did work on. (I also know of a 1996ish Cavalier that is all leaked out due to a hole.) So is the difference the size of the leak?

But I do support you, if a system was opened up like that, I have never heard of not evacuating it!

ehenry · Jun 27, 2008

Re: A/C tech ?

I"m no A/C tech believe me. If it get past an automotive or farm tractor system I wont fool it. In my experience when you evacuate a system you're accompishing a couple things. 1. checking for leaks 2. removing any moisture in the system. A totally empty system will take freon wheather its had a vacume pulled on it or not. CHances are there is moisture in and it will cause problems.

I just had to plunk down $1875 bux for an evaporator to be installed on my home unit. Atleast your buddy did his himself and is still holding his cash......looks like he's fixing to have to unwallet some of it tho

dimock44 · Jun 27, 2008

Re: A/C tech ?

A long time ago use It was a widely used practice to dump Liquid freon into the liquid line until it was up to pressure and then open the suction line and dump the charge. Repeat 2 more times. I knew a guy that didn't own a vacuum pump for the first 3 years he was in business. Fastest way to evacuate is to pull 3 vacuums and break the first 2 with nitrogen and the third with freon. Most of the moisture leaves with the nitrogen which would normally have to be boiled off.

TommyA · Jun 27, 2008

Re: A/C tech ?

The purpose of putting the system under a vacuum state is to remove the moisture. By reducing the pressure in the system it lowers the boiling point of water and allows the moisture to leave through the vacuum source. A thirty minute vacuum is normally recommended then close the valve leaving a pressure gauge to see if the system leaks. If all is well you then add freon to the recommended pressures. Moisture in the system will freeze causing a blockage at the transition between high and low pressure sides thus preventing cooling. The DIY freon kits are good for bringing a system that is low in freon but are not really made for a full recharge that has not been evacuated. A system that still has freon in it will still be moisture free.

SS MAYFLOAT · Jun 27, 2008

Re: A/C tech ?

Just what I thought and trained. I know his high head pressure which causes his amp draw to go sky high is due to moisture and air in the system. Its gonna be real hot this weekend. I'll have him come aboard my boat when I crank the Tstat down to about 64. However, I find that a bit to chillin

BTW, my unit is a homemade unit made from an old window A/C. All I did was dump the old air cooled condenser and replaced it with a water cooled one. I use the lake water like in a regular marine unit. Works excellent and all I got invested is $300 for the water pump to circulate into the watercooled condenser.

I think I will offer to pump down his unit and do a proper evac on it free of charge. I know if I need help, the dock mates there will be glad to help without asking for $$$$$......Thanks,,,,,,,be back late Sunday, Have a great weekend

..........SS

TilliamWe · Jun 27, 2008

Re: A/C tech ?

That's a mighty nice thing of you to offer SS.

Tommy, thanks for the clarification on the DIYs working on a system with "low" freon, not "empty"!

SS MAYFLOAT · Jul 1, 2008

Re: A/C tech ?

I finally convinced him that he really needed to dump the system and do it right. Pumped down the unit, purged his system with nitrogen, evacuated it, and then weighed in the gas.

His evap temps before would only get down to about 50 to 55*. Now the output air at the evap is 41* and his amp draw is a lot lower.

Later Saturday night, I found a bottle of Jack Daniels by my cabin door with a thank you note on it