Question on adding gas to BD35 compressor

[Warby12]

Hi, our fridge (Isotherm, Danfoss BD35 with a thin evaporator plate), is not cooling well. There is only frost on 50% of the plate and it's only using 2 and a bit amps. From all the wisdom gleaned from this site, this suggests low on refrigerant. The performance has gone down very slowly over the last year.

I guess it has a small leak, possibly from the quick connectors, which I cannot sort right now, maybe in a couple of months.

I think I will try adding a little gas, and before I buy a charging hose and some R134a, I just wanted to ask you wise people if a standard hose will connect to the can of 134a in the pic below and then to my compressor's service port on the BD 35 (also pictured with green dust seal on it).

No adaptors needed?

[Warby12]

Oh yeah, I also trouble shot by bypassing the thermostat, checking voltage, checking field windings and earth leaks on the compressor terminals, and swapping in known good controller module. I've done my best
In quite hot weather today (30C) with thermostat bypassed, it's run hard and well but with low amps and 50% frost.


So what hose do I need, if anyone knows?

[Coolerking]

The fitting on the unit is 1/4" male flare.
you need a gauge set that allows you to get from the can you posted to the fitting on the unit, its under the green shrink wrap, while being able to control the flow of refrigerant into the system.

[wingssail]

Originally Posted by Coolerking

The fitting on the unit is 1/4" male flare.
you need a gauge set that allows you to get from the can you posted to the fitting on the unit, its under the green shrink wrap, while being able to control the flow of refrigerant into the system.

Take the dust cover off and inspect the fitting. Probably Coolerking is right, after all he is in the business, but mine was a simple shrader valve, and the store where I bought my can of R34a had a hose and gauge and an adapter that fit my shrader valve. I was able to screw on the adaptor the connect the hose and gauge, and proceed according to the instructions to refill my system.

Since your system is not totally empty maybe a shot of gas will do it. Try 3 seconds at a time and leave it for 10 minutes. It might take a few. Don't rush things, an over filled system can damage the compressor.

Put you fingers on the joints and fittings, if you find one which is oily, that's your leak. A small bit of tightening might cure it. Some people swear by "stop leak" but I don't know the long term consequences. Just putting in gas occasionally seems like a no-brainer to me.

[Warby12]

Thanks Coolerking, from what I can understand the r134a can (on order) has a 1/2" acme thread and as you say the unit has a 1/4" male flare. Just gotta get a hose to connect them with a valve on the can end of course.



Do I need any odd adaptors for the gauge set?


(This is just to get us home, where I'll have it leak tested and regassed by a refrigeration guy)

[Warby12]

Hi wingssail, Yes it's definitely a schrader valve. I took the dust cover off and it measures 11mm (or 7/16ths approx) across the thread. Seems a bit big for 1/4"?

I am will dig deeper. I need to order something soon as it's getting hotter and we won't be near reliable help for a few weeks at least.

Thanks for your help

[Dsanduril]

Don't get terms confused, a Schrader valve is actually smaller and finer threads. It is the standard valve on automobile tires (and many bicycles).

A 1/4" SAE flare uses a 7/16-20 male thread. That's a 1/4" SAE flare (with a small cap on the flare).

[Dsanduril]

Or it's new enough that the black is a Flare Seal.

[Warby12]

Got it! That makes more sense (confusing)



Thanks guys, I've done an order, fingers crossed.

[wingssail]

Originally Posted by Warby12

Hi wingssail, Yes it's definitely a schrader valve. I took the dust cover off and it measures 11mm (or 7/16ths approx) across the thread. Seems a bit big for 1/4"?

I am will dig deeper. I need to order something soon as it's getting hotter and we won't be near reliable help for a few weeks at least.

Thanks for your help

Yes, I recognize this fitting. Right now I don't know what it is called (It is 2:00am and I have been into the rum tonight) so you have to get to a store or find out the name of this kind of fitting.

That is a common fitting.

[Coolerking]

The black rubber o-ring is meant to stay in the cap, take it off the fitting before you attach the gauges.

[Warby12]

Originally Posted by Coolerking

The black rubber o-ring is meant to stay in the cap, take it off the fitting before you attach the gauges.

Thanks for that, I did wonder

[s/v Jedi]

Can’t you reach the quick connectors? All you need to do is take them apart, replace the O-ring and screw them back together. When that’s done, top up the gas and you should be good to go

[Warby12]

Hi S/V Jedi, the connectors are behind some cabinetry, (which I put in ). I'll be cutting some access and leak testing them.


I will try and track down replacement o-rings to have them ready for the evacuation to come.

[wingssail]

Originally Posted by Warby12

Hi S/V Jedi, the connectors are behind some cabinetry, (which I put in ). I'll be cutting some access and leak testing them.
I will try and track down replacement o-rings to have them ready for the evacuation to come.

My point above is that since your unit is still partially working I'd suspect that a shot or three of gas will put you right. I would not take apart the quick disconnect fittings unless you are equipped to vacuum the system and completely refill it. Plus, of a certain age the fittings are not reusable without gas loss at least.

A real easy leak check is to wipe the fittings with your finger. The gas has oil in it and if it is leaking out there will be wet oil on the fitting, usually the high pressure side. Even then, you could stop the leak with a little tightening of the fitting (use care and two wrenches so as not to break the solder joints). AND they sell stop leak which is supposed to be good.

So my recommendation is, do not open those fittings unless you have to.