Refridge Recharge

[djousset]

*Coming at this with zero knowledge base

I may need a control unit for the compressor and may also need a recharge for a very old polar mate system.

Is it safe/possible to remove the compressor unit and take it off the boat for diagnosis/recharging?

Can today’s HFC refrigerant be substituted or will I need a new setup?

[Tin Tin]

if you don't have the manual find it here, the trouble shooting guide should be your first port of call: http://www.tropicalmarineairconditio...ets/L-2058.pdf


The best way to get these going properly is to take the whole fridge out and take it to a DC fridge shop that does boat and RV fridge work.

[pcmm]

You can't really effectively recharge the system (not the unit) by taking it off the boat. If you can get then entire system out of the boat without damage, only then can you have it diagnosed, maintained and maybe get it back in. that's a big maybe though.

What issues are you having?

[JimsCAL]

If you remove the compressor (really condensing unit as it includes the condenser) you will lose the refrigerant charge. That is technically a violation of the law. Proper way is to recover the charge, not vent it to the atmosphere. Then when you reinstall it, you will have to evacuate the system, then recharge.

Chances are you unit uses R134a. There should be a label someplace to comfirm that. Just top up or recharge with that.

[Bowdrie]

How old is "old"?
Most any unit that was made in the last 35 years or so will be a 134 unit, (I forget when the change from R12 occurred).
If the male/female couplings at the unit are still operational then the condensing unit can be removed without loss of charge, but on old systems that is a big "if", over time the valves have a habit of sticking.
Sometimes it's just better to have a tech "scope out" the system before deciding to take things apart.
If it won't turn on/run then the problem is generally electrical, the control module or thermostat, maybe even just corroded/loose connections.
I would guess that on a system that old that it will be pretty simple to diagnose.
Although, a common source of leaks on old systems is because of corrosion that happens on the pressed aluminum evaporators.
Someone chips/scrapes ice off with a hard object, a bit of paint comes off, and now we have a spot for a potential leak over time.

[djousset]

Thanks for all the tips.

I found a label, it is R143a
It seems to cycle on and off frequently so I am thinking control module (those things are expensive!) I installed a new thermostat this season so no concerns there. Also keeping an eye on the evaporator plate for moisture/ice build-up to see if there is any sign of leakage. I reached out to one tech but ...... you know how that goes. Hence the plan to remove it and try to diagnose myself.

[Mnbear]

Try recharge your self. 134a and car recharge kit . 12 -15 lbs when running 25 when shut off. This worked for me. Good luck

[Bowdrie]

Originally Posted by djousset

I may need a control unit for the compressor and may also need a recharge for a very old polar mate system.
Is it safe/possible to remove the compressor unit and take it off the boat for diagnosis/recharging?

Originally Posted by djousset

It seems to cycle on and off frequently so I am thinking control module (those things are expensive!) I installed a new thermostat this season so no concerns there. Also keeping an eye on the evaporator plate for moisture/ice build-up to see if there is any sign of leakage. I reached out to one tech but ...... you know how that goes. Hence the plan to remove it and try to diagnose myself.

If the unit runs, and turns on/off with use of the thermostat then the control module would appear to be working.
PCMM, in post #3 is correct, the unit and the evaporator need to be connected together to be effectively charged/recharged.
With the compressor running and the fan turning, continuing to plan to remove that unit will only increase your problems, nothing to be gained going in that direction.
With a system that old if you did remove everything you'd best just put in a new system.
It cycles "frequently"? how much is frequently? Those types of systems will generally run around a 60>70% duty cycle unless one has a small box or one that is very well insulated with good seals on the lid.
Are you seeing any ice/frost build-up? if not, the unit probably is undercharged and, (assuming no visible physical damage,) there probably is a leak somewhere.
If I was looking for a leak the first two places I would investigate are the spots where the tubing goes into the evaporator, and, (don't laugh,) the cap and Schrader valve that is used to access the system.
Someone will need to find that leak and fix it.
Then the unit will need to be vacuumed and recharged.

[SV Confianza]

We'll need more info about how often it cycles on and off. Also need to know if it is still cooling, somewhat cooling, or not cooling at all.

Your system has a Danfoss compressor (probably BD35F, maybe BD50F?). They actually use very little refrigerant, and you have to be very careful not to overcharge them.

If you attempt this yourself, find the service valve (usually the top left one sticking out), and you can connect a car recharge kit to it. Do NOT use anything with stop leak or any additives, just R134a. There's an adapter that goes onto the service valve so you can connect the quick connect fitting.

If you're not comfortable that you have the right valve, DO NOT ATTEMPT. You can seriously injure yourself trying to charge the wrong side.

To charge, you'll want the fridge running (powered on, thermostat turned all the way down to run). Open the valve to the can to charge (can watch some YouTube videos on this). Since these use so little refrigerant, you'll want to count to a whole two Mississippi and then close it again. That's it. Then let it run for 20 minutes and see how it is cooling. Overcharging is very easy, and there's a number of problems that it can cause (but shouldn't kill it).

The "cycling" could also be the compressor trying to start, failing, and then going into its wait period. It might never be starting. Then it will try again in 20 seconds or so. This can also happen if the controller has gone bad (has happened to us).

You can use an LED to get the error code that it is throwing in this cycling case. This is a pre-made one - https://coastalclimatecontrol.com/sh...mbly-p95699140

You can also use an analog voltage indicator/multimeter/probe with a light to do the same thing by just touching the error light contacts. I haven't had luck using a digital one, since it doesn't reset fast enough for how quick the lights are supposed to flash.

Before I end up typing a whole novel on this, just send me a direct message if you want some better help. Might be easier to just walk you through it.

[fourlyons]

Good advice above. The spec sheet for this unit says Grunert added dye to the original charge. You can buy a cheap black light and use it to look for leaks.

Also, if you recharge the unit you will know it's correct if the evaporator frosts up, but not the tube returning to the condensing unit.

Wear gloves and eye protection when connecting hoses to recharge.

[djousset]

Thanks for all the good suggestions.

It does run and it does cool but the cycling is excessive. Not a battery issue so I suspect the controller. (pics below).

It's clear from these responses that this job is a stretch for my skill level. I think I can comfortably rule out a couple things by checking the connections, the evaporator and the tubing. The recharging process makes me nervous, I'll read up more on that.

[Mnbear]

First pic upper left is the valve to put 134a

[fourlyons]

Originally Posted by Mnbear

First pic upper left is the valve to put 134a

It's a little hard to tell from the picture, but isn't that the high pressure port? I would charge through the brass caped port on the right, the one coming off the compressor. That will be the low pressure side.

[Bowdrie]

Originally Posted by fourlyons

It's a little hard to tell from the picture, but isn't that the high pressure port? I would charge through the brass caped port on the right, the one coming off the compressor. That will be the low pressure side.

You are right.
In the upper part of the pic we see two tubes with kind of a horseshoe bend, one of the tubes with a foam cover.
The tube without the cover would normally be the high side tube, it looks as though someone retrofitted a Schrader valve there.
The Schrader at the right mounted on the little U-bend fitting right off the compressor is the low side connection that you would use for charging.

[djousset]

So green is the high pressure side valve and yellow is the low?