So i have a small 4000btu wine cooler that is for cooling down a wine room. The issue is the air coming out is not very cold. This system uses a capillary tube and a hermetically sealed pump so its just like a refrigerator. It uses r134a as the refrigerant. When i turn in the unit the condenser gets hot and the evaporator gets ice on the first tube going into the evaporator. The temperature of the air coming out drops to 63f and then stays there. Once the air reaches 63f the condenser starts to cool down. After running for a few minutes the pressures look like this. It’s currently 75-80f out. Does this indicate a clogged capillary tube? Also when i turn off the unit i can hear a sort of gurgling.
Help diagnosing small ac issue.
- Thread starter joegreen
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no the ice clears up . yes it has been charged to .53lbs which is what the label says
I think its undercharged. At 75-80f i'd be expecting pressures of 45 low side, 170 or so high side. Is there a fan on it, and is it working?
Did you charge it? DId you purge the lines of your gauges and the refrigerant line? It takes little air/moisture in a small system to not cool well. I might vacuum the whole thing down well if you are not sure.
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Owen Lucas
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Dumb question, but did you pull a good vacuum before charging it? I'd empty the system, flush with nitrogen and pull a long vacuum + recharge. Make sure there is no air in your lines before recharging too, as mentioned earlier a tiny amount of air, that could be present in your lines could be causing a problem. The tool below can help you purge out any "de minimis".
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So the system is from 2015 so its fairly new and its very clean inside. The unit had this cooling issue when i got it. I checked for leaks and there were none so i refilled the system. I drew about a 4 hour vacuum with my 2 stage vacuum pump. Yes i purged the refrigerant lines on the gauge set before filling the system to limit any air intake. After a refill it still has the same cooling issue. If i remove the ducting from the condenser the high side pressure will start to climb into the 200-250 range which leads me to believe the pump is working properly and i capable of making good pressure. What else besides a clogged capillary tube can cause this issue assuming the charge is correct and there is no air or moisture in the system?
Owen Lucas
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Could be just a faulty unit, maybe using a thermal imaging camera could be helpful to see if something odd is going on.
Yeah i wish. Im just a home gamer
Expansion valve?
this unit does not have an expansion valve just a capillary tube which is a fixed length and inner diameter that meters the refrigerant.
What did u used weight the charge in? Do u have valves at the end of the suction hose? Did u only put in the .53 lbs and not figger in hose volume lost and when removing the hose from schrader? Did u install a schrader ? Your short agree with Spasm 3. System like yours are critical charge lose 1 oz its short.
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I use a small digital scale i can weigh the 12oz cans on. A little guess work was involved but i put in a little more than the .53lbs to try and compensate for losses.
I took off the capillary tube and tried to suck through it with my mouth and it felt like there were no restrictions. I know not proper or scientific. Anyway i reattached it and drew a couple hour vacuum. I then recharged and added a little more refrigerant than the last time. The temperature on the evaporator side still dropped exactly to 63f. I was looking at the label today and see it lists the high and low side pressure. Is this the pressure i should be seeing when properly charged or is this a max pressure i might see on a very hot day? Maybe this indicates my pump is bad if the high side pressure is too low. Also included pic of how im weighing the refrigerant in.
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This is likely your issue, not enough airflow across the condenser.
I would leave the ducting off for a day or more and see how it affects performance, not just pressures.
Hmm. I don’t see how there isn’t enough airflow across the condenser. The unit is very compact and uses solid foam to direct the air. When there is good airflow across the condenser the high side pressure stays low. When i remove the ducting around the condenser the high side pressure starts to rise as the airflow across the condenser dramatically decreases. Here is what the unit looks like.
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Oh, I see how it is arranged now. Perhaps the problem is on the evaporator side then. Make sure the fins are clean on both sides and that all fans turn on and appear to be running at the same speed. Perhaps there is a leak somewhere causing a portion of the air to bypass the evaporator?
If only part of the evaporator is getting cold it's either undercharged or the metering device is plugged,stuck etc. You said it's a tube. I'm not familiar with that but I'd guess it's like an orifice tube. Gotta be one of those 2
Your suction pressure is lower than it should be. Lack of airflow across the evaporator will cause low suction pressure. Low on charge will cause it to be low too though. This thing being a critical charge unit you have to make sure it has exactly the right amount of refrigerant in it. Needs to be within an ounce of what it calls for. When you are charging it leave your high side hose off. The amount of liquid refrigerant that the hose will hold is enough to throw your charge way off. Also if the capillary tube was plugged your head pressure would be excessively high which it isn't.
Checking your superheat at the compressor would tell you a lot about whats going. That might be something your not familiar with doing but its easy to figure out. Take the line temperature of the suction line at the compressor and subtract the evaporating temperature and that gives you superheat. Low superheat would indicate lack of airflow across the condenser and high super heat would be low on charge. Example would be anything less than 6 degrees being low and even being zero because its possible to have no superheat at all. A superheat reading over 30 would say to me low on charge.
Checking your superheat at the compressor would tell you a lot about whats going. That might be something your not familiar with doing but its easy to figure out. Take the line temperature of the suction line at the compressor and subtract the evaporating temperature and that gives you superheat. Low superheat would indicate lack of airflow across the condenser and high super heat would be low on charge. Example would be anything less than 6 degrees being low and even being zero because its possible to have no superheat at all. A superheat reading over 30 would say to me low on charge.
