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Give the guy a break hes just rusty, I didn't start working in the field until a couple years after I graduated at first I too did not remember many things I was taught.......and after a few year I still don't LOL

"It's still a good practice to write down the gross weight, so if it accidentally gets lost you can still figure it out by math. (accidentally touching a button, bumping the scale and causing the battery to jump and rebooting, etc)"

Point taken, I believe I have done all of the above at one time or another. LOL

Originally Posted by Black Adder

forget all the adding and subtracting when weighing in charge, just hit the tare button on the scale when the bottle is on there and it will zero out. stop adding refer when it reaches the desired amount, in your case 5.5 lbs.

It's still a good practice to write down the gross weight, so if it accidentally gets lost you can still figure it out by math. (accidentally touching a button, bumping the scale and causing the battery to jump and rebooting, etc)

hey.... you just posted that figured out manually what sh and sc should be.....ummmm.....

how?

cause with txv you charge by sc.....
cause with piston you charge by sh...

so how exactly do you have the magic number for both????

forget all the adding and subtracting when weighing in charge, just hit the tare button on the scale when the bottle is on there and it will zero out. stop adding refer when it reaches the desired amount, in your case 5.5 lbs.

I am going to give out one more bit of advice. It is my opinion that your unit does indeed have a TXV but it is inside the evaporator cabinet.

It is not metering correctly. As you add refrigerant your head pressure climbs and your unit shuts off on high pressure switch,

Open that evap cabinet. I think there you will find your problem. A restricting TXV.

Good luck.

Originally Posted by commtech77

Fieldpiece does make a tool that has a T attached to the top of it and you can run in series to a reclaim. set up.

But I hear you. It doesn't come with a thermal nuclear particle accelrator that breaks down the R410A on a atomic level turning it to a lemon fresh scent of oxygen and confetti.

ROFLLLLLLLLLLLLLLLLLLlll

That sounds fair; I will find the schematics for the unit online and double check a few things. I do know from talking to a tech at a company here in town that overcharge and undercharge are the 2 most common problems he runs into following up previous techs. If all the members that list themselves as HVAC techs make this mistake, how can this be so? Poor training, not paying attention to their gauges, not reading the manufactures specifications? I cannot believe all of them are not good at what they do. However one old timer told me if he wants to add some refrigerant, he just hooks straight on and puts the bottle upside down and more or less swishes it back and forth until he thinks it is about right. I asked him how he knows what to charge the customer and he said he wins some and losses some but he saves time. Not very scientific sounding to me even with his 30 years in the trade. No kidding everyone you talk to seems to have their own way of doing this.

Yes experience is everything in this trade but not that kind of experience. cheers

Thanks for the advice

Actually school should give an idea of what a overcharged system acts like.

Lets assume you paid attention but are just rusty. Type in over charged AC unit on your search engine. and you'll come up with numerous resources and generic troubleshooting charts that have been around for ever.

Based on the luck you've had so far what makes you think you at are capable of resolving this issue.

It' s basic stuff you're running into. AC 101 kind of issues.

So even if its your unit you're asking qualified individuals to step you through something you dont seem to have a firm grasp on.

Its up to those guys whether or not they want to participate in your folly.

A good HVAC tech is dependant on quality tools but tools do not make the tech.

Knowledge and experience do. I know that unit has to have a schematic on it. With it you should be able to know for a fact if it does or does not have hi pressure switches.

If you are what you say u are then a sincere good luck to you as you progress into the field of HVAC.

Understand it is a field thats heavily dependant on hands on experience to grow as a technician. Maybe if you have a choice chose your battles a little better.

Charging equipment seems to trip up to many people that HAVE experience but just dont follow good service practices

Sounds great guys.

Let's clear up the following:

I did go to trade school last year and I did pay attention fully.
I do have the EPA Universal cert for handling refrigerants
The unit belongs to me so I am only destroying what is mine and I am using it to do exactly what is needed field experience.

I have a recovery unit, recovery tank, vacuum pump, micron gauge plus a good set of yellow jacket gauges.
I have manually figured the super heat and sub cool and they come out from 18 to 22.
I have pulled the front on the A-Coil and there is no txv on the A-Coil. I wish there was since all of the Install information that came with the install indicates a TXV.
Finally I agree, it is probable there are non-condensable in the line due to the fact that the compressor is stalling and when adding just a little more 410 the high side (discharge) pressure shoots up to over 600psi. I don't believe that is normal.

No amount of practice in class will teach you what a compressor greatly overcharged will act like or what the low and high side pressures will indicate in all scenarios. In class everything is done to lab specifications and hits the mark most of the time. No extremes tend to occur and all EPA rules are followed. A perfect world.

Once again this is my system so before I go out and do serious damage to someone else’s unit, I would rather destroy mine if that is what it takes.

With that said, yes the tool from Fieldpiece is a SSX34 and it does indicate it can be used for calculating super heat and sub cool on a system in real time with built in pressure charts. Of course it is taking the line temp from suction or discharge line to calculate from. I have found that if the temp clamp is not insulated (as in a hot day etc.) the temp reading may not be accurate. But that occurs even using the gauge, you have to insulate the temp probe for a good reading. I will use the temp gun next time as suggested and see if it is right on. I will start carrying one with me. It has a T on top of the unit and can be used to charge through the unit by attaching (example) a line from the new tank of 410a to one side of the T. The other runs to the low side suction line since as you know 410 cannot be added except as a liquid. The unit in (real-time) will calculate the super heat or sub cool as it is being added. If you need to recover some refrigerant the recovery tank is changed with the virgin tank and as it is extracted, the sh or sc will be recalculated as it is withdrawn. Not sure why it is bad to use new technology if it works well. I was in the computer repair business for 15 years and if you did not readily adapt to new technology you were quickly left behind.

Yes easy to do (weigh the bottle first, write down the starting weight and calculate what should be added). According to the manufactures chart is should be 4 lbs 15 ounces under 15 ft. add 10 more ounces for the 40 ft. line set. I believe that is 89 ounces or rounded is 5.5 pounds. My line set as stated in and earlier post is 40 ft.

I do believe at this time it is overcharged and I think to get it back on track is best to just recover the refrigerant and pump it down to more or less 250-300 with the vacuum pump. Then weigh the new 410 tank and subtract the needed 5.5 pounds to indicate the stop point. At this point unless something else such as a restriction is causing this then the super heat should be right on.

Anyway I will follow this course of action.

Thanks for the suggestions.
wlamore

Originally Posted by commtech77

Fieldpiece does make a tool that has a T attached to the top of it and you can run in series to a reclaim. set up.

But I hear you. It doesn't come with a thermal nuclear particle accelrator that breaks down the R410A on a atomic level turning it to a lemon fresh scent of oxygen and confetti.

They don't? o well lol I'll stick to my 2 yellow jacket manifolds

Originally Posted by Bigpapi08

Why did you have to scare him away i wanted to know where he got his "purchased a new fieldpiece superheat/subcool monitor. You can add or subtract refrigerant via the tool" i need one of those so i dont have to carry a recovery machine or tank

Fieldpiece does make a tool that has a T attached to the top of it and you can run in series to a reclaim. set up.

But I hear you. It doesn't come with a thermal nuclear particle accelrator that breaks down the R410A on a atomic level turning it to a lemon fresh scent of oxygen and confetti.

Originally Posted by WMG

Check the return air and supply air and take difference which is the split. An Infrared thermometer makes it quick and easy, just the way I like it.

Quick , easy and inaccurate. IR theometers are only good for quick checks.

Plus if you're getting readings at the registers you're picking up heat added to discharge air from the 100 degree plus attics that are common in Texas.


Is it really that difficult to climb in the attic and do it right ?

Quick and easy is not a motto that inspires quality or accuracy. It sums up whats wrong with this industry in that techs dont posses the work ethic to give their customers 100% of their efforts.

Why did you have to scare him away i wanted to know where he got his "purchased a new fieldpiece superheat/subcool monitor. You can add or subtract refrigerant via the tool" i need one of those so i dont have to carry a recovery machine or tank

I told him last week that most HVAC problems aren't refrigerant issues. I guess he decided my information was wrong. Now he has a system thats overcharge and still not working right.

I also told him to give the sight his information so he isn't a guest anymore. At this point I think without having a moderator see his EPA number and confirming he has one I would be leery about giving him any more information.

He has " been told" of pressure switches ???


I guess that motivated him to go out and over charge a system.

Because ANYONE can do this kind of work. A chimpanzee with down syndrome and AIDS can do AC work in his sleep right ? Blindfolded in his sleep !

I think its funny. This is obviously a DIY scenario that's gotten out of control.

I wouldn't want to be the TRAINED TECHNICIAN that has do go clean up this guys mess.

Check the return air and supply air and take difference which is the split. An Infrared thermometer makes it quick and easy, just the way I like it.

I think he meant graduated from "EPA school", not trade school.

" However this a fixed orifice or at least no TXV is showing on the outside of the A-Coil."

Cmon man get a grip Most coils these days have the txv in the case not on the outside. Open up the damn thing and make sure of what you've got there. Obviously you have no business playing with the charge on this thing. I told you once and I'll tell you again, it's easy pull the friggin charge out and weigh it. Then weigh in the proper amount before you start adjusting things. I would say at this point you don't have a clue how much refrigerant is in that thing.

Originally Posted by commtech77

I suspect otherwise.

Someone who " graduated " recently would know what a high pressure switch is. What a low pressure switch is.

If your are using the meter to remove refrigerant where are you removing it too ?

Whats your high side pressure anyway ? Low side pressure ?

If you haven't recieved the minumum amount of eduction to know that these switches exist and are easy to spot on the schematic AND on the unit why are you monkeying with the charge ?

Chances are its seriously overcharged or you managed to get air in it or both.....and you need to move from a DIY save a buck mindset to calling a proffesional before you do major damage to a very expensive component.

I like your post! There aint no way this guy went to trade school. And if he did he must have been a sleep the whole time.