e34 - what does the AC refrigerator switch do

[redbeard1]

Hello all,

I'm having trouble figuring out what the AC refrigerator switch does on my boat. Our newly purchased boat (PC 34-200) has a refrigerator that looks like the factory setup so I thought others might know what the AC refrigerator switch does.

Using refrigerator while sailing - no problems here. I flick the DC switch marked refrigerator and 5 seconds later the cooling unit is humming.

Using refrigerator with shore power - Switching on the AC main switch + AC refrigerator switch seems to do nothing. To use the fridge on shore power, I need to turn on the AC main switch, then the AC battery charging switch, then the DC refrigerator switch.

The refrigeration unit works very well and my above workaround seems to work fine. I only ask because I assume if the factory put in an AC refrigerator switch then it must have a purpose.

Any thoughts?

 

[fool]

Hello RedBeard,

Some compressors are both AC/DC and some with an automatic switch. When hooked to shore power and the AC circuit turned on the 'fridge runs off of AC even if the DC switch is on. But with the DC switch on and a cut in power to the AC, either by unplugging or flipping off the AC switch, the compressor will automatically run off of DC. This is the way my Vitrifrigo compressor is rigged to run the ice box.

Nothing wrong with running the unit on battery or with a charger attached. From what I've been told it won't harm the battery although I imagine there is some loss of efficiency in the calculations. I'm sure there will be someone with more experience making calculations than I.

Cheers,

Max

 

[redbeard1]

Thanks for the reply Max.

Good to know my workaround should not damage anything.

I am still curious why my ref. unit will not work when 1) connected to shore power, 2) AC Main switch on, 3) AC refrigerator switch on, 4) DC refrigerator switch off.

Speculating out loud, I'm pretty sure my unit (Frigoboat Paris 35) only works on DC power. Maybe this Paris 35 is an aftermarket replacement put in by the PO. That would explain an AC switch that does nothing.

Alex

 

[Christian Williams]

My Dometic is DC only. Check the identification stuff on the compressor unit and Google it to see if your brand model has an AC option.

My electrician says running a DC frig off batteries kept up by a ("smart") shore charger is good for batteries.

 

[EGregerson]

AC Dc

I don't have the 'factory' reefer setup, but i have the breakers for both DC and AC on the Electrical panel; and an after market reefer system. (works great). The AC default should kick in when it senses AC power is present; so the master AC breaker needs to be 'on'; as well as the Refrigerator circuit breaker. if ur AC reefer circuit switch is inoperative, but the battery charger circuit works to power the fridge, i suspect the wire is connected to the wrong breaker.

Caveat: u may be running off DC only even tho u have the AC breakers on; and have the DC breaker on. Does it run with only AC main and AC Refrigerator breaker 'on'?

 

[Loren Beach]

More Fridge Trivia

Our '88 model has the same panel as my friend's '86 E-38. Probably common on late 80's EY and Olson's.
PSC did use a different arrangement of breakers, so this trivia might not help too much.
On ours there is a marked DC breaker for the fridge, but no breaker for an AC fridge option.

When I installed a fridge conversion kit many years ago I put in a Frigoboat system and it was all DC. Recently it was replaced with another brand of fridge that was also built to run on only DC.

When the boat is at the dock, it is plugged in to shore power and in turn the battery charger is on all the time.
As Christian stated this does no harm to the batteries at all.

When away from home dock, our stock 55 amp Moto alternator keeps the house bank charged up and we can anchor for two days and nights and still start up the diesel with our house bank (two Trojan GC batteries).

Loren

 

[redbeard1]

Thanks Christian. I just finished reading the manual and can find no mention of AC. I'm thinking the unit is DC only. I also have a good battery charger so I think my "workaround" of using AC main + AC battery charge + DC refrigerator switches will be okay.

Egregerson - Thanks for reply. Away from shore, unit will only run on DC refrigerator switch on. On shore power, unit will also only run with DC refrigerator switch ON. On shore power, I will also turn ON the AC main + AC battery charge to keep my batteries from running down. If I run AC main ON + AC battery charge ON + DC refrigerator OFF, unit will not run.

In summary, I think my DC refrigerator switch needs to be ON even if I am on shore power because my ref. unit cannot accept AC. I think the AC switch may have been installed for another ref. unit that has since been removed or in case a DC/AC unit was ever to be installed.

Thanks for all replies. This website is great.

 

[fool]

Manuals for the Paris 35 (f) are easy to find on Professor Google. Near as I can tell by a quick read Frigoboat is mostly 12/24V, with no AC connection.

Not too surprising this is an aftermarket installation. I'm under the impression that 30-40 y/o compressors are a bit long in the tooth otherwise...

 

[tmjkelley]

Our '88 model has the same panel as my friend's '86 E-38. Probably common on late 80's EY and Olson's.
PSC did use a different arrangement of breakers, so this trivia might not help too much.
On ours there is a marked DC breaker for the fridge, but no breaker for an AC fridge option.

When I installed a fridge conversion kit many years ago I put in a Frigoboat system and it was all DC. Recently it was replaced with another brand of fridge that was also built to run on only DC.

When the boat is at the dock, it is plugged in to shore power and in turn the battery charger is on all the time.
As Christian stated this does no harm to the batteries at all.

When away from home dock, our stock 55 amp Moto alternator keeps the house bank charged up and we can anchor for two days and nights and still start up the diesel with our house bank (two Trojan GC batteries).

Loren

I'm about to install a fridge conversion in the galley icebox with the compressor under the port settee. I'm having a problem getting the AC from there to the distribution panel on my E34. How did you do it?

 

[HerbertFriedman]

On my 87 E34, I just replaced the port refer with a new Frigobot unit. It came equipped to run on DC only but as an ad on, the tech who installed the unit put on an AC switch unit (made by Frigobot). The old unit was also wired to run either on AC or DC so the wire from the house panel was already in place. According to the tech, when the AC (shore power) is on and the ckt breaker marked "P&S ref" is switched on, the refer runs on AC not DC. I am not sure why the Previous Owner wired the refer for both AC and DC operation but I chose to keep that arrangement.

The switch marked "P&S refer" powers both port and starboard units, the starboard unit under the nav table, no longer works but I have not chosen to replace it, I think the starboard unit is a freezer while the port unit is a refer, and I have no need for a freezer unit.

 

[Loren Beach]

Ac?

I'm about to install a fridge conversion in the galley icebox with the compressor under the port settee. I'm having a problem getting the AC from there to the distribution panel on my E34. How did you do it?

Not understanding the question. :nerd:
Since both our older and now the newer refrigeration compressors run on only DC, only a #8 pair (boat cable) of DC wires come from the breaker on the DC side of the panel. No AC is involved, and there is no such breaker on the stock panel.

Now you guys have me wondering if there are compressors actually wired for both DC and AC. Gotta say, I cannot see why.
Even if there is such a device, you still have to have your AC shore power on in order to have the fridge run all the time at the dock. We leave our fridge on continuously year round, except for mid winter when we are not using the boat at all.
We have done this since acquiring the boat in the 90's. The shore power has to stay on so that the charger can float the batteries, anyway. That way we have ample power for the DC automatic bilge pumps that watch over the boat when we are not there.

Mind you, I am not criticizing, but am a bit puzzled.

Aside: also a bit envious of the port and starboard reefer boxes on the E-34!

 

[Christian Williams]

To add to the confusion, both the AC and DC panels of my boat have a circuit breaker marked "Refrigerator".

The DC breaker goes to my Dometic, in the lazarette.

The AC breaker wires remain neatly coiled and secured under the cockpit floor, where the factory left them "just in case."

 

[HerbertFriedman]

Loren, I and the tech agree with you regarding the use of the AC power for the refer/freezer units because, as you and the tech agree, that at the dock where shore power is available, there is no problem using the battery to run the units and the battery charger to keep the battery charged. In my case, the PO wired both refer units directly to the battery bypassing the main battery switch so that that main battery switch need not be on. When I discovered this, I added a fuse to each refer line (at the battery).

The only situation I can see is that if the battery is not available (service issues or whatever), you can still run the refers off shore power. I guess if you have tons of food in the those refers, and did not want to risk spoilage, AC shore power would be needed, but that seems like a pretty poor argument to spend the money to add this AC power conversion. But I did it anyway.