Results 1 to 13 of 49
09-04-2012, 01:00 PM #1
Cant get bubbles out of sight glass
Went on this call at a church, back for leak check today, but pressures where I left them. Turned the unit on and it was 76 inside and turned down to 72. Pressures were 200/75. Coil split was 18, and sweating all the way through on all u bends. Super heat was 2 to 3 and subcool was 1 to 2, with bubbles in sight glass, but very minimal, almost milky looking. T-stat satisfied in a half an hour. Went over evap coil with leak detector and nothing. Went to outdoor unit and found a leak on top of suction service valve with cap off( not shrader portion) tightened cap up and not leaking. Found a leak on true suction service port. Seemed like someone had over tightened the shrader b/c could not get core tool on shrader, so leak locked cap. My boss says to keep throwing refer to it but that goes against the grain. Indoor piston(#83) low super heat(measured at service valve), but has low subcool, and bubbles in sight glass. Added a total of 7lbs counting both visits. I knoiw it has to be overcharged, but delta t good and RH 50% db 70 wb 60. Outdoor unit Trane M# 2TWA0048A3000AB S# 3471N213F, indoor unit is 4 ton dont have numbers though. I wonder if the comp valves are bad? Should have tried to pump down. At a loss with this one, any help would be appreciated.
09-04-2012, 01:26 PM #2
Bubbles in sight glass
Posted this problem in cant get bubbles out of sight glass but didnt go through, so try again. What would cause low super heat, low subcool, sight glass bubbles. Indoor temps are RH 50%, db 70, wb 60. Set stat from 76 to 72 and satisfied within 45 minutes. Pressures are 79/205, sh 2 to 3, sc 1 to 2. No temp drop across sight glass, valves all the way opened. Boss said to keep charging it so I did, about 7 lbs worth, still bubbles. Trane hp M# 2TWA0048A3000AB S# 3471N213F. This thing has to be overcharged, but temp split is good, supply 73 and return 53. I probably should have tried to pump down b/c I think the compressor valves may be bad. Indoor unit is also 4 ton but dont have numbers. I am at a loss with the bubbles in the sight glass, any help is appreciated.
09-04-2012, 02:47 PM #3“I am glad that I paid so little attention to good advice; had I abided by it I might have been saved from some of my most valuable mistakes.” - Edna St. Vincent Millay
The critic is a prisoner to his own experiences and perspectives, erroneously believing his limited experiences are the sum of all truth.
No Guns…No Freedom…Know Guns…Know Freedom.
09-04-2012, 03:14 PM #4Professional Member*
- Join Date
- Dec 2002
- SouthEast NC ICW & Piedmont Foothills
4 ton hp; no reason for a site glass; especially if it's at the hp
what Mr.B said!It`s better to be silent and thought the fool; than speak and remove all doubt.
09-04-2012, 03:57 PM #5
09-04-2012, 04:17 PM #6
Pumping down and starting fresh with new refrigerant and filter drier would be my guess...adding refrigerant to a system with non condensables would not help anything.
Checking compressor amps and system pressures would give you an indication of id the compressor is bad or not.
What refrigerant are you running?
09-04-2012, 04:44 PM #7Regular Guest
- Join Date
- Jul 2010
- From AZ to N.E. OHIO
Sounds like its overcharged, does the system need a fan cycle control installed? Cooler outside than inside. what were the pressures before adding refrigerant? R-22?????
09-04-2012, 04:58 PM #8Professional Member
- Join Date
- Apr 2011
Suction pressure doesnt look like the valves are bad, what was the temp outside? You said the glass was "milky", could there be moisture in the system, has anyone had the system open? Think I would try removing the charge, replace the dryer, pull a good vacuum and recharge with new refrigerant.
09-04-2012, 05:00 PM #9
How is your airflow? Belt drive? Sheaves/belts/etc in good shape?
09-04-2012, 06:26 PM #10
What was the pressure and superheat subcooling after you added all the refrigerator
Sent from my PC36100 using Tapatalk 2
09-04-2012, 06:58 PM #11Regular Guest
- Join Date
- Aug 2012
Based on the those measurements and your observations I would suspect contamination of the refrigerant (R22/R410a mix).
Recover the refrigerant and try a clean charge in it.
09-04-2012, 07:43 PM #12Regular Guest
- Join Date
- Nov 2011
09-04-2012, 07:49 PM #13
You are over charged.
First sight glass charging is wrong with those conditions
AC unit are designed at 95f
When it's around 70 condenser is too efficient and subcools gas faster than normal.
So sight glass will not be clear.
Go back to basic
Check superheat chart and input your conditions
I believe it's 16 SH
ignore sight glass.
If they are going to run Ac with these conditions
Then you will need a low ambient control
To prevent freeze ups