Refrigerant Overcharge

 
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Old 06-12-2009, 03:16 PM   #1
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Refrigerant Overcharge


OK, so now I get to display my lack of knowledge. I am here to learn so hopefully I can find some way to give back as well.

Can Refrigerant Overcharge cause icing?

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Old 06-12-2009, 08:01 PM   #2
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Re: Refrigerant Overcharge


I have seen systems 100%-200% overcharged, showing normal or freezing temps, they might have air in the system also & dirty coils or air filters that were not checked.

Best course of action is recover refrigerant, weigh in new charge AFTER cleaning coils & air filers.

Amazing that compressors even withstand this.
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Old 06-12-2009, 08:52 PM   #3
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Re: Refrigerant Overcharge


Overcharge can cause icing as the evaporator gets flooded with liquid refrigerant, not all of it boils off to a vapor and some can slug back to the compressor and wreck the valves.
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Old 06-13-2009, 12:44 PM   #4
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Re: Refrigerant Overcharge


An over charge in its self won't cause freezing(of the coil).
There are usually other things at work that cause it to freeze because of the over charge.
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Old 06-14-2009, 10:03 AM   #5
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Re: Refrigerant Overcharge


The simple answer is yes. A fixed orifice system is more susceptible to icing than a TXV.
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Old 06-15-2009, 02:15 PM   #6
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Re: Refrigerant Overcharge


Overcharging is the most common rookie mistake! And it's the worst thing you can do to a compressor. Most of the time it's caused by a plugged air filter or dirty evap coil.
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Old 06-16-2009, 11:45 PM   #7
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Re: Refrigerant Overcharge


hvacwalter
Why are you asking this question.
If you have a specific situation then please list all the info you can.
Equip brand, year, size, lineset size, refrigerant, equip location ie. residential, commerical, crawl, basement, upflow, counterflow etc.
Only then can we try to accurately find a solution to your problem.
If you are just asking for general education then I am sure that we can help you with this, however, keep in mind that there are several factors involved with A/C and or refrigeration that can cause or create the illusion of overcharging.
Taking the time to learn basic fundamentals will be well worth the time and money.
Please do not try to learn by takng the quick answer and running with it. Learn how to ACCURATELY DIAGNOSE the problem/s to determine proper service.
Always start diagnosis by VERIFIYING THE COMPLAINT!!!! if you cannot verify the complaint, dont fix anything. there is nothing wrong with circling in a holding pattern.
many times a 10 min interview which involves YOU actually listeneing to your customer will shorten hours of diagnosis.
Always verify the repair. sometimes this requires a call back or another visit, but it must be done.
Let us Know!!!
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Old 06-17-2009, 01:00 AM   #8
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Re: Refrigerant Overcharge


Yeah, and don't forge the DNA sample too! LOL
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Old 06-17-2009, 09:49 PM   #9
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Re: Refrigerant Overcharge


The first rule is when confronting a problem, go back to the basics & think about it awhile. Unfortunately, this business is very scatter-brained in education & training because what we do is educated guesswork. I don't think we should be so hard on someone in the trade earnestly trying to learn or find a solution. In the heat of battle we all can end discombulated, tired at the end of the day. Suggestions regarding the basics to be posted are helpful though. We all were once rookies, actaually still are.
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Old 06-17-2009, 10:32 PM   #10
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Re: Refrigerant Overcharge


Quote:
Originally Posted by gene2 View Post
The first rule is when confronting a problem, go back to the basics & think about it awhile. Unfortunately, this business is very scatter-brained in education & training because what we do is educated guesswork. I don't think we should be so hard on someone in the trade earnestly trying to learn or find a solution. In the heat of battle we all can end discombulated, tired at the end of the day. Suggestions regarding the basics to be posted are helpful though. We all were once rookies, actaually still are.
i concur.
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Old 06-19-2009, 05:58 PM   #11
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Re: Refrigerant Overcharge


I've seen compressors encased in ice due to overcharged conditions.
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Old 06-22-2009, 04:25 PM   #12
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Re: Refrigerant Overcharge


if the unit is grossly overcharged the evap pressure and boiling point would be higher than normal, this would get you further from freezing. however a slight overcharge could cause freezing if it's compounded with a low load situation (not enough air going over the coil). the overcharge usually is caused by not properly evaluating the unit and assuming low pressure meant low charge.
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Old 06-26-2009, 12:37 AM   #13
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Re: Refrigerant Overcharge


I have never heard of an a/c system icing from an overcharge without other underlying conditions. Roboteq can you give some details on how these overcharged systems caused icing. I have only seen overcharged systems cause icing with refrigeration systems.
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Old 06-26-2009, 01:58 AM   #14
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Re: Refrigerant Overcharge


Quote:
Originally Posted by heatgain View Post
I have never heard of an a/c system icing from an overcharge without other underlying conditions. Roboteq can you give some details on how these overcharged systems caused icing. I have only seen overcharged systems cause icing with refrigeration systems.
Yes, there has to be other issues. The worse I have seen was with a system where the tech had charged a five ton piston metered system to the proper superheat, as per my instructions to him.

When the system, which was already oversized for the appliction most times (School rooms relying on the system to do the job empty or filled with heat producing children) did not cool despite the tech telling me the superheat was right on the money, I checked it out myself.

Well, I get to the job and sure enough, the system is running. A five ton, 10 SEER Goodman with a Bristol recip, it was just humming away....with the compressor and suction service valves encased in crystal hard ice.

I chip away the ice from the service valve and take my superheat. Yep, right on the money. Something that struck me as a possible indication of a problem that the tech did not bother to tell me was the suction line temperature was 4 degrees.

So, into the attic space to take a look at the coil. The coil was so covered with debris (this was a system put back into operation shortly after a major hurricane and it had run without a filter) that I could not even make out that it was a coil.

So, I cleaned up the coil as best I could, fired the thing back up and removed several pounds of refrigerant that the tech had added in order to get the superheat proper with no airflow.
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Old 06-26-2009, 09:53 AM   #15
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Re: Refrigerant Overcharge


simply put, in and of itself...NO. could you find an overcharged system icing..Yes, not due to the over charge but to another problem that exists!
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Old 06-26-2009, 03:06 PM   #16
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Re: Refrigerant Overcharge


Quote:
Originally Posted by RoBoTeq View Post
So, I cleaned up the coil as best I could, fired the thing back up and removed several pounds of refrigerant that the tech had added in order to get the superheat proper with no airflow.
I would think the superheat would have been low well before he got the proper amount of refrigerant into the unit, if he was actually measuring superheat, you should have found it undercharged after correcting the airflow issue

more likely he was trying to get the suction pressure up and wasnt measuring superheat
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Old 06-26-2009, 11:49 PM   #17
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Re: Refrigerant Overcharge


Quote:
Originally Posted by Swampfox View Post
I would think the superheat would have been low well before he got the proper amount of refrigerant into the unit, if he was actually measuring superheat, you should have found it undercharged after correcting the airflow issue

more likely he was trying to get the suction pressure up and wasnt measuring superheat
The technician was a government maintenance tech for the school system trying to get air conditioning up and running after a major hurricane hit. So, there is a very good chance he was trying to get the suction temps up, but, the superheat was proper when I first got to the job. The problem of course was having proper superheat with too low of a suction line temperature. The saving grace was a constant heat load.

I have pics of that job in my files somewhere if carnak says it's ok to post them now.
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Old 06-29-2009, 12:08 AM   #18
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Re: Refrigerant Overcharge


well what type of metering device was the system equipped with? a TXV system is charged via subcooling and fix orifice is done with superheat. maybe thats the problem.
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Old 06-29-2009, 12:55 AM   #19
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Re: Refrigerant Overcharge


Quote:
Originally Posted by nicktech View Post
well what type of metering device was the system equipped with? a TXV system is charged via subcooling and fix orifice is done with superheat. maybe thats the problem.
I'm not looking for a solution, I already resolved the problem. This was in 2005, not a current issue.

The system was fixed metered. That is why I told the technician to charge to proper superheat. I was giving these techs basic charging outlines for them to get many systems up and running and was not specifically going over this one system with them. This was just one of the systems they wanted to know if the hurricane had done damage to.

My job was to ascertain if the hurricane damaged the systems. There were hundreds of systems that needed to be checked for hurricane damage. This was just one that stuck out because it was operating with it's compressor encased in ice and was severely overcharged.
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Old 10-18-2010, 10:53 PM   #20
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Re: Refrigerant Overcharge


Quote:
Originally Posted by RoBoTeq View Post
I've seen compressors encased in ice due to overcharged conditions.
No you have not chubbles
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