Post a reply to the thread: russell walk in cooler
You may choose an icon for your message from this list
Please enter the name by which you would like to log-in and be known on this site.
Please enter a password for your user account. Note that passwords are case-sensitive.
Please enter a valid email address for yourself.
Will turn www.example.com into [URL]http://www.example.com[/URL].
close the liquid line service valve. Pump it down and do the temp pressure check on the high side verses the ambient at the condenser.
Originally posted by refer dude 2479 That is easy to eleiminate or prove. Pump it down and do a pressure temp check. Looks like thats the way to go. Perhaps dandyme could just shut down condensing unit and wait for 20 minutes and tell us the box temp and his suction press/temp.
That is easy to eleiminate or prove. Pump it down and do a pressure temp check.
#18 psi suction if box was 40deg or so. Its 53deg air in to evap, so normally you would expect 30-35 deg evap temp w/r12? Looks more and more like its not r12 in there.
Wow, talk about over doing the simple. If you think the gas charge is wrong or contaminated pump the system down and let it set. measure the ambient temp and compare to the refrigerant pressure. Check your temp pressure chart to see if the pressure matches what it should be for R-12. This should take all of about 15-30 minutes tops, including a small break for restroom and coffee if required. If the system looks like it is still R-12, focus on the compressor. It is not doing its job. TX valve is not starving the coil!!! If it was the pressure would be lower than it is. Starved coil does not cause increase in suction pressure. You need at least 18# suction for R-12 to make a med temp cooler. To quote the great Scotty from Stat Trek.... "I can not change the Laws Of Physics Captain"
Dan... Just hate to say this but, 1. One of your guys may have mixed the refrigerant by mistake. Or.. 2. If it was ever low on refrigerant and there was a blend in the system you have to determine if fractionation has occurred. (Loss of component blend) 3. If a zeotropic blend was used, a full sight glass indicated an overcharged system. 80% charge when replacing 12. You need to see those bubbles. If you see your TXP hunting you can rule out the valve being bad but not its adjustment. If you can't get the evaporator suction line temperature below 50 degrees then take this 10 minute step before evacuating and virgin charge. Take a suction line temp at the evap coil. Run the TXP in (counting the turns) two turns. After a few minutes recheck the temp on the suction line. You need to get that suction line temp down a good 20 degrees, 50 is way too high. If the temp goes up, reverse the TXP 4 turns out and recheck suction line temp. If no change, recover and virgin fill and mark the system with refrigerant type for the next guy. The above posts are good and directing you to the correct area. With that system clean and the compressor good, 50 degree suction line at the evaporator, fan blades turning the correct rotation then this issue can be corrected. It has to be one of three things or a combination of. 1. Overcharged, remember you said the hi pressure limit was kicking from time to time 2. TXP out of adjustment or bad 3. Refrigerant mixed or fractionated
Lusker: Been doing this restaurant for several years. All records show to be R-12, never changed over-we don`t know why. Sight glass clear. Contamination has crossed our minds. Owner wants issue resolved before his vacation 07-04-04.
Dan... Is this a new customer? Have you or your guys worked on the box before? Are you sure you have R12? Could you have non-condensables in the line or a mix of refrigerant? It acts like it has 22 in it with a 12 power element. What size TXP? and is it an R12 head? With a blend like R414B (Hotshot) your superheat says you are starving the coil. How is the sight glass? Full or bubble? [Edited by lusker on 06-17-2004 at 11:04 PM]
Issue not resolved yet. Compressor pulls down to 20" vac. Haven`t spent much time on this box, we can`t seem to get there until midafternoon--------that bites, guy comes in at 8:00 every morning. This unit also has an intermittent high head trip out. I was really hoping the condenser would not pump down.
dandyme: I curious what you found out and how you repaired this. I sure would like to know so I can store that info up in the brainbox.
Thanks.... ucp-yes, 1st thing after I walk in, jab temp probe in coil. Evap & Cond coils already clean. pumped down last night.........didn`t bypass lp cutout....shutdown at 5#
The higher head pressure could also indicate there's a blend of some sort in there and the hack that put it there didn't mark the unit. I'd still guess bad valves. Close off the suction and see how low it'll pump down. If it won't go to at least 10" Hg, replace the pump.
[i] If TXV was starving coil suction would be low not high. If you want to maintain regular cooler temps with R-12 you need at least an 18# suction. Check the chart. [/B] Your right, I think we all are trying to get him there.
read this post. same problem almost http://hvac-talk.com/vbb/showthread.php?threadid=53788
P.S. another random thought. High discharge might be another indicator of bad compressor not dirty condenser. Broken disch valves will reduce refirerant flow thus high suction, but cause an awful lost of heat to be passes to the high side due to disch gas entering and leaving cylinder with broken valves. Lots of heat generated but no refrigerant flow. Thus the high subcooling. Focus on the compressor.
Originally posted by ucp R12 34psi = 36deg 185psi= 132deg My first impression is metering device is starving evap. Head pressure is a bit high also but it might be dirty or high ambient. I would suggest looking at expansion valve adjustment/replacement and checking/cleaning condensor coil both. If TXV was starving coil suction would be low not high. If you want to maintain regular cooler temps with R-12 you need at least an 18# suction. Check the chart.
change the compressor. 34# suction will not get you close to temp.
checking/cleaning condensor coil both. I agree with ucp, clean the coils then check your system
R12 34psi = 36deg 185psi= 132deg How did you get evap coil 46deg, thermometer inserted into coil? Let me know if Im wrong. Evap superheat is 50deg minus 36deg, 16deg evap superheat. Condensing temp is approx 132deg minus 72deg liq line temp, total subcooling 60deg. Air in 53deg minus 36deg boiling point, 17deg temp difference. 4 deg drop across evap coil. My first impression is metering device is starving evap. Head pressure is a bit high also but it might be dirty or high ambient. I would suggest looking at expansion valve adjustment/replacement and checking/cleaning condensor coil both.
won`t bring box below 53 deg suction 34# Head 185# 4 deg drop across coil 53-49 evap coil 46 deg suct line @ evap 50 deg liq line @ evap 72 deg Russell cond RC11/2H12 mod 89F10374 ser Russell evap AE36-140 010521 is this unit overcharged R-12 system box 12x8x7 any suggestion??????? [Edited by dandyme on 06-15-2004 at 11:54 PM]
Forum Rules
