rtaa 185

[bcooling]

Hey Guys,
Had a post some time ago about a trane rtaa 185, that was tripping on loss of oil flow, or code 198. The second compressor did not trip on 199, it runs fine. The unit is a package not split.
I had alot of feed back and was offered alot of diagnostic tips, including Rtaa-sb-12. Have been through all points, the only deviation from norm is that the subcooling was a little low.

Now here is the punch line. I jumped the oil pressure wiring together and placed the ohm meter across the switch, and within 9-or 10 seconds the switch closed, yet the machine still shut down on code 198.

Now, can I swap the compressor protection module that operates compressor b to the a compressor. I dont believe their are compatibility issues. The A compressor is 100 ton. I am aware of the lip seal problem, yetI dont believe thats it because it shut down with the switch jumped out. The Compressor b is an 85. Has anyone had problems with the compressor protection modules just acting up and nothing be wrong with refrigeration or mechanical??

Thank in advance for the response, you Guys are always so helpful on this site.

[maxster]

check the wires into the panel from that jump and ring them out make sure the pin is solid onto the UCP.pull the pin off the UCP and jump it then put your meter on the pair of wires at the oil switch(hanging loose not connected).put your meter on AUDIBLE for OHMS and pinch the wire all the way up into the UCP moving it around as you go.if you solid and the meter stays constant could be the wires into the pin or the boot itself......that closure is nothing but that to the UCP that oil is into the hellical.

[chillrdude]

Originally posted by bcooling
Hey Guys,


Now here is the punch line. I jumped the oil pressure wiring together and placed the ohm meter across the switch, and within 9-or 10 seconds the switch closed, yet the machine still shut down on code 198.




If you jumped the oil pressure switch wiring together, the micro could not "see" the switch open within the allotted time frame (I think its like 6 seconds) thus it would have failed on 198. I'll find and RTAA-IOM-3 and verify the time, 9-10 seconds seems like a long time, what is your head pressure and have you verified the calibration of the oil switch, supposed to be set @ 50 psid.

The compressor modules are all interchangeable, just make sure the dip switches and overload settings are right for the 100 ton circuit and the 85 ton circuit.

[bcooling]

hey chillrdude,
head pressure is fine , I cleaned the coils for kicks anyway. the Calibration is fine. Correct me if im wrong but the oil pressure switch has to make within 20 seconds of compressor startup or the machine will fail on 198. If the switch does not open on shutdown then the machine locks out on 1A5. So if the switch was jumped on startup, then how could it lock out on 198, as it did. Wouldnt the jump simulate the ops making?? maybe i misunderstood your post.
Thanks

[chillrdude]

My bad, I misread your problem, thought it was happening at shutdown, Maxter's probably got it right, check the connector where the wires slide into it, and also check the wires out. was the switch jumpered before the compressor started or did you jump it out right after startup.

[service guy]

This may sound stupid but did you check wiring from oil switch to chiller control panel? I had the same problem recently and found a wire was rubbing against chiller frame repaired wire and never tripped out again.

[bcooling]

hey guys,

Thanks for the posts. The jumper was placed prior to compressor start. I have checked the wire connections in the pecker head as well as the connections on the compressor protection module. I will however trace the wires and physically look at every inch. It just seems that if the jumper was in place and the compressor tripped out on 198 code , that the problem may be in the compressor protection module. I am going to swap the a and b modules and see if b trips out on the same code. I am also going to check the model # of the oil pressure switch to see if it is the one that trane had trouble with.

Thanks again.
Bcooling

[mfriar]

if you switch modules you will have to set the dip switch code on the comp board as they r different for a 100 ton and a 85 ton. how long does the machine run at start up? make sure all cond fans work.a cond fan out will also make it trip on oil pressure

[bcooling]

I have checked the fans and cleaned the condensor. When it trips its usually within a minute. Other times the compressor will run for hours. Its an intermittent problem.
Thanks,

Bcooling

[mfriar]

it really sounds like a lip seal failure.i have put on several of the kits.there is a service bulliten that will walk you thru the check out procedures;i.e back pressure on the slide valve

[v1erne]

I just kinda skimmed thru this, the oil pressure switch is not supposed to "make" this would indicate too high of a drop across the oil filter. early rtaa had slow response to condenser fan control under high ambient/load situ.
hwat year is the machine