Air Conditioning - 4 ton scroll amp ?

I have a 5 year old ruud uamb048jaz & an 18 year old ruud air handler that has a new efm & a 5 year old 4 ton evap coil with txv. I am getting the following reading on the cond. while its running
8.5 amps on start wire to comp.
14.5 amps on common to comp
13.5 amps on run to comp.
pressures 58/190 charged with help of sight glass I got about a 15-20 degree t/d from return to register depending on how hot it is outside
I change the filter every 3 weeks & hose the c-coil once a month. My electric bills suck & I know the main reason is because the attic insulation sux & it's almost impossable to add more insulation because of the design of the attic with all these vaulted ceilings.

FYI I do have an epa license but haven't done a/c in a long time hurt my knee now I do mainly appliance repair & sheetmetal work.

So whats the question?

sorry forgot about that part. Are these compressor readings normal? What kind of amp draw should a 4 ton copeland scroll be pulling?

The AMP draw for the unit should be on the name plate.Like all the 4 ton different units from one company have different AMP draw and Max fuse.

also.

Might also take some line temps to go with the pressures.

If you take the access panel off to lok at the compressor nameplate look on the back for a charging chart.

Just because the sight glass is clear doesn't mean it's charged correctly.

Airman, I don't if it's the way you put or that and your pic - but you had me laughing!

Chris

The questions to that answer are as follows we will list the Question and then the Answer for clarity sake.
Question #1 Should we be giving specific DIY advice here that would encourage a non EPA certified individual to grab a set of guages and test their unit??
Answer. Probably Not
Question #2 What information would be appropriate for this particular poster that may actually help him and still not encourage people to break the law?
Answer. Specific prudent steps should be taken prior to hooking up gauges these are
A. Evaporator/Condenser coils and blower wheel to be thoroughly cleaned and a new return filter installed.
B. Ductwork manual and or motor controlled dampers to be checked verified as operational and positions noted on a ductwork schematic, all supply and return openings to be verified as unobstructed. Airflow velocity and static pressures of the duct work to be checked (a shortridge instrument works well here).
C. Next we can tackle the electrical checks if we have the instruments and skill needed. Verify Voltage at disconnect and then at contactor. Check/replace capacitors. Check amp draws on compressor/condenser fan and blower motor. All readings should be written down and saved for future reference.
D. Once we have achieved steps A B and C we can check the system internal pressures if we have the Equipment/EPA cert and skill sets to do the job safely. Post the following info (after the unit has run and stabilized) for a fun internet diagnosis. Outside ambient air dry bulb temp. Return air wet bulb temp. Return air dry bulb temp. Supply dry bulb temp. Low side pressure and line temp at outlet of Evaporator. High side pressure and line temp at outlet of condenser. Also note if when your dog lies down to sleep does his head consistently point North or South. Has nutin to do with AC just a survey!

mrfixit, did you notice this in the first post?

FYI I do have an epa license but haven't done a/c in a long time hurt my knee now I do mainly appliance repair & sheetmetal work.

and the poster was asking about the electrical current draw of his unit. He didn;t ask about any of the actual epa type stuff.

The plate on the unit says
max breaker 45 amp (which is what I have)
min breaker 35 amp
comp RLA 19.3
LRA 137

contactor readings are fine/ caps are good/ cfm pulling 1.8 amps.

& on the EPA cert... I have a 1, 2 & 3 Universal certification from Ferris State University. I would give you my licence # to prove it but It is my social security # so that ain't happening.

I know my questions may seem stupid being that I am certified & all but I haven't worked refrigeration in a while & I tend to foget what I learned if I don't use it on a regular basis.

I need to get a temp probe for my meter to measure for super heat more exactly. All I have is my regular meat probe style thermostat.

I was only asking for opinions on the amp draw of the compressor to see if that was within the normal range.

so anyway, if the tag actaully lists the compressor RLA, it would seem you are well within the engineered current draw. Actually if the last spec you gave is actually a compressor spec, your current is low, which could be indicative of a low charge or a failing compressor (internal bypass causing a reduced load)

So, as long as the pressures are good and the thing cools as designed, it would seem all is well in freon land. The unit may simply be inefficient or additional insulation needed (I know, I read) may be the reason. for the expense.

I would tend to worry about the current draw less and the pressure readings and performance more.

You had pressures and said your were EPA certified. Good enough for me.

Your RLA is 19.3 and high leg is 14.5 sounds fine.

But, I would check the charge more closely than a clear sight glass. Look in the unit for a charging chart.

Does it have a txv in the air handler? If so you'll need to charge for subcooling not superheat.



Chris

what is the best way to measure for subcooling. I do have a e-coil with a txv. Is there a specific temp prob you all use or just a regular temp themocouple that would plug into a muli-meter. The way I was shown to charge a unit with a txv was by using the sight glass. There is a temp chart inside the condenser access panel but its hard to read. My amperage reading was actually about an 1.5 higher a little while ago but a friend of mine that does a lot of commercial & residential work gave me a can of "zerol ice" (http://www.zerolice.com/contractor.htm) he had a lot of success using it. A lot of the units that had compressor blankets on them after he put in a can did not need the blanket anymore. They ran more quiet and energy efficient. I saw it first hand on my unit it dropped the compressor amps a lil & it was quieter. I'm not trying to sell this stuff just putting it out there if no one has seen it before. I do appreciate all of the helpful posts you have been putting up.

Amps look a bit low pressures look a bit low 58 puts the evap coil in danger of freezing up, a more desirable number on the low side would be 70 72 normally on a nice 85f day but I dont really know your outside or inside ambients, all that other stuff I listed is good to get information and can really help fine tune a system but only people that do this for a hobby (like me) would mess with it on a little residential system I guess.

Sub-cooling is measured the same as superheat except it is done on the liquid line & the temperature is compared to the high side gauge rather than the low. Subcooling will, like superheat, vary with conditions. The information here may help.
http://www.udarrell.com/ac-trouble-shooting-superheat-subcooling.html

Note: If the condensing unit, evaporator coil, & air handler (or furnace) are ARI matched, you should be able to obtain charging data from the manufacturer.

You may have been "shown" how to charge with a sight glass but (there is always a but) that doesn't mean the charge is correct. IF you do have a txv there are times a properly charged system may show bubbles in the glass.

Since I don't know if you were ever taught this or may have forgotten about it let me explain subcooling and superheat.

We want subcooling to ensure we have liguid at the metering device, keeps our evap coil from becomeing a block of ice. R-22 boils at -41 degrees, but lets use water. As you know water boils at 212 and condenses at 212, so water at 112 while warm/hot is actually subcooled 100 degrees.

On the flip side we need superheat to ensure that we have only gas and no liquid returning to the compressor, but we don't want too much as the gas returning also cools the compressor motor. Water will change to steam at 212, so steam at 222 is superheated 10 degrees.

Charge for subcooling if you have a txv, superheat for a piston or cap tube.

All that said, If I were you I'd call the manufacturer get them to email a charging chart.


Chris

Jarredsdad, I really appreciate all the time you have taken to explain this. It is much appreciated you are very helpful. I installed this condenser about 5 years ago & I changed the evap coil at the same time. I would have put in a new air handler but would have been a nightmare to do the way the old one & ductwork is burried in the attic rafters. So I just rebuilt the air handler new coil/ horizontal drain pan & a ran a new properly sized line set. Vacuumed the whole set up for hours. When I charged the unit it was the first time I was thrown that my gauges weren't at the usual 70/200 psi neighborhood so I had my buddy come by & double check it & got the thumbs up from him (he is really good). I wasn't trained as well as I should have been (never went to school for it.. it was on the job training) for a company that did service contract work that would start their ac guys day with 10 calls + adds. Hence my lack of superheat & subcooling charging. Then I blew out my knee real bad & never made it back out to field work again. I worked in the company's repair shop on washers/dryers/microwaves/icemakers that couldn't be repaired in the home. They had me doing sheetmetal work making a/c schrouds(doghouses) & drain pans for units that the parts were NLA even that old fat slab york that had all the little seperate drain troughs under each part of the coil, kind of like the new rheem w-coil pans. I got real good with the sheetmetal & a torch. We used to pull coils from the contract holders house & I would presure test them & do the leak repairs & someone would reinstall them (the company never wanted to buy new coils unless they had to). The majority of refrigeration work I did was on home refirgerators where I only had to use a scale to charge them and a ton of window units. I know I am running on here but I do appreciate you all showing me the right way to do things. I only work on my equipment & my families, no more service work. Here are a few little tips I can contribute to some of you:that product " Zerol Ice" does work lowering the amp draw & making compressors more quite. I had a lot of success using "Superseal" for sealing refigerant leaks in the past only seen it fail once(give it a shot on a window unit), & for some techs that are iffy about doing leak repairs on aluminium try using a laco heat stick (http://laco.com/ProductDetails45.aspx) it works on copper too but it works great on like the old carrier coils. Just need to clean the area of any oil.. heat the loop a little bit just to warm the metal & rub the stick on it. I tested it on a coil I was going to throw away, fixed the leak, charged the coil with 600 psi nitrogen & it never leaked. Thats when I started trusting it.. never had it go bad on me. Anyway thanks again guys.

Thanks for the tips also.

I tyried a different aluminum stick a couple time never any good luck with it.

I'll try yours, can't hurt.

Keep in touch, let us know what the final outcome is.

"Vacuumed the whole set up for hours.", how many microns is that?

Chris

I too want to thank you for the aluminum repair tip. I've never had any luck trying to repair aluminum coils but I have never tried the Laco product.

If you can provide make & model numbers for the condensor & evaporator, I might be able to find some specs. If I can't get specs, I should be able to give you an idea as to what to look for in subcooling.

The vacuum pump I used had a micron gauge on it I think it was like 500 microns I pulled on it.

I think I can make out the chart on the condenser cover. I'll probably tackle that this weekend. I'll post back what I find.

The Laco heat stick is great, really reliable & easy to use. Just clean the area good. If the loop is ugly clean it up with sandpaper and some solvent to remove any oil residue if its not that ruff than just use a solvent like acetone etc. to get rid of the oil & lets the stick seal smoother. You don't need much heat so you don't run into putting a hole in the aluminum. I used to just wave my torch back a forth with just the end of the flame. Then you rub the stick over the area and it melts on the loop just like a crayon would. You should be able to pick it up at any supply house like Johnstone or Marcone appliance parts. Even the aluminum solder & flux repair kits aren't that bad to use just takes a lot of practice. Find an old aluminim coil that going to get tossed take it home & practice I got to the point with the aluminum solder kits that I could braze beer cans together. But once you get used to that stick you don't want to bother with the extra work with the aluminium brazing kits.

You guys are the best... thanks

Finally got a chance to check the charge today. It was 90 degrees outside. Chart on the unit said at 90 the high side should read 214 for factory sub cooling charge. I got 60 with suction line temp of 45 over 215 with a liquid line temp of 93. I got good air flow with an 18 degree td.