View Full Version : RTAA unloading issues
08-15-2008, 07:12 PM
Working on an RTAA300, circuit 2, which has a CHHB100 compressor. The compressor already has the lip seal kit on it from several years ago. When it starts for the first time after an extended shut down or over the weekend it cranks up at about 135 amps. It runs for 10 to 15 seconds and cuts off with no alarm and then restarts and will unload down to 40% like it should. I keep getting the 195 code for low evap temp because I am starting at close to full load at some point, when I am not there, of course. My subcooling and superheat are perfect at full load so this is an oil control issue. I can pull my load and unload wires off the board and at any % of load I hold steady. I don't think my slide piston is leaking by. My unload stays energized at shutdown for 60 minutes. Why do I keep loading up on shutdown and is it normal for the 10 to 15 second cycle I explained earlier. Seems different from the way all the other RTAA machines I work on act. Thanks for your input.
08-16-2008, 12:21 AM
When was the last slide valve piston rebuild? Sounds like its due.
Take the pill filters out also.
08-16-2008, 09:49 PM
If the pill filter is taken out do you risk getting dirt into the valve or is it strictly overkill? Come to think of it I have never seen anything in a loader filter.
08-17-2008, 12:59 AM
My understanding is the pill filter is installed to catch any manufacturing debris that may be in the system. Removing them after the machine has been in service for a while poses no problems.
08-18-2008, 10:43 AM
I am experiencing the same problems with a rtaa185. See my post for some other ideas that the guys have posted.
08-18-2008, 06:33 PM
If my old mind serves me right, there is a re-route kit to the compressor to relive the pressure. I will have to find the bulletin.
08-18-2008, 07:06 PM
He already has the lip seal kit on it . My first bet would be the pill filters . Take them out you dont need them . Then once you get it going steal power from the terminal strip in the bottom right of the panel (top connection is 110volts) remove the load unload wires from the board and excersize the piston. dont load it to fast you will trip it out , you should be able to get the amperage down as low as 40% check item 27 menu 2 if you cant then you have a stuck piston . Time for a piston rebuild
08-18-2008, 08:07 PM
Thanks for the replies. Did some research on this compressor with the customer and it has not had new rings on the piston so I am going to pull the pill filters and re-ring the piston at the same time. Amazingly it was not in alarm this morning. I also found out this has been a problem for about 18 months. The lip seal kit was installed in 04 and an oil filter about a month ago but customer says problem still persist. Keep giving ideas and I will post with results. Thanks again.
08-19-2008, 09:08 PM
...When it starts for the first time after an extended shut down or over the weekend it cranks up at about 135 amps...
"First Start Syndrome
This is a phenomenon that is seen on older compressor on the first start of the day. The compressor will start loaded the first start only or after the compressor has been off for at least 8 hours and then compressor will operate normally. This may cause High Pressure Cutout and/or Low Oil Flow Trips. This happens as the seal ring on the piston begins to wear. This can be corrected by simply replacing the piston."
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