SMC Discussion Areas

Calling on your expertise to help me figure out the icing issues. This is after running about 12 hours. Thermostat is barely on. Temps inside machine aroun 37f-38f. Machine in garage, ambient temp ~ 70f. Compressor cycles on every 3-4  minutes and runs a minute or two.

(https://www.hostpic.org/images/2009242106540120.jpg) (https://www.hostpic.org/view.php?filename=2009242106540120.jpg)

Many thanks.
Jim

Looks to be a possible case of an overcharged system or a restriction in the accumulator, the rest of the evaporator is frost-free, so the freon starts evaporating just beyond the last row of coils suggesting a flooded evaporator  , can you check the evap - low side pressure at that system tap I see in the picture, should be sbout 15-20 psii for R12

Thanks JohnieG.

I wish I had a set of guages to hook up and check pressures, but sadly I don't. Maybe I can find a cheap set at Harbor Freight nearby. The picture might be somewhat misleading as the coils would ice over if left running.

Jim

I'm not a soda machine compressor expert, but most AC systems freeze up when they are LOW on freon.

Is the fan behind the evaporator working?

I'd imagine that if the evap' fan wasn't running the entire coil assembly would be Iced, not just the accumulator? 

Yes. The fan is working fine. The whole unit would frost/ice over if left running for 2 or 3 days. Door seals appear to be fine too.

That’s because they run R22 ( newer systems R410 or other R22 replacement) , it has a much higher system pressure but a lower temperature glide, an HVAC system is a medium/high temperature application really designed for dehumidification of the home, it operates well above freezing.  but when there’s a leak & lower pressure at the evaporator the R22 will quickly slip below 32-F & ice over the coils.

So as the pressure in the system drops, the temperature at the evaporator actually gets colder, but there’s less gas in the system to absorb the heat from the passing air, so an under charged refrigeration system will tend to only frost up at the end where the capillary tube enters the larger evaporator tubing,  on an overcharged system the freon doesn’t begin to transition back to a gas until it’s well towards the end of the evaporator coils ( a flooded evaporator) usually leading to the suction line icing as well, sometimes all the way back down to the compressor,  

The added service value & the spare can of freon I see leads me to believe that it had a leak or someone thought it was low on freon & the system was recharged & possibly over charged in the process if the person adding R12 to the system didn’t use a scale or otherwise install the correct charge.

I suspect that is the case (overcharged). When I got the unit it came with 3 extra cans of R-12. I have no idea when or how much was added. Would it be as simple as vac'ing out the unit and recharging to proper level?

Thanks again.

I am certainly not an expert but it might be time to get a local technician to take a look at the Freon level.  If the unit is overcharged then a local tech could recover the extra without releasing it into the atmosphere.  Good luck and please keep us updated on what you find.

Just thought I’d give this a bump... any resolution to the icing problem?

Sam wants to know

Guess the machine fell on him....   :laugh: