RTAAO8O Low Evap Temp

[PACKLEADER]

Trane RTAA0804XLO1A30CB S# U00508585
Trips on Low Evap Temp,not on initial start-up but after unit approaches set point and unloads then when it loads up again it jumps fron 48% to 98% and the suction pressure drops around 28psi and the Evap Temp sensor reading also drops to 17 degrees and locks out

[aejlpnk]

Check the load signal and the load solenoid. May have a faulty valve.

[engine chiller]

They are 3 things that i can think of:

1 unloader valve problem(could be strainer under valve body)

2 load sol valve stuck open.

3 low cw water.

[jemawalton]

Sounds like the piston is sticking. The load solenoid continues to apply pressure gradually until it builds up enough for it to move and then Whamo!

[PACKLEADER]

Sounds like the piston is sticking. The load solenoid continues to apply pressure gradually until it builds up enough for it to move and then Whamo!

THE MALE UNLOADER PISTON

[jemawalton]

You lost me on that one. I am refering to the piston upon which the load and unload soleniod valves apply pressure in order to cover or uncover more of the rotors in order to load and unload the machine. Check the pressure on the piston as it relates to the actions of the load and unload soleniod valve.

[mtntom]

Sounds like the piston is sticking. The load solenoid continues to apply pressure gradually until it builds up enough for it to move and then Whamo!

Whamo-Tried and true technical term

[PACKLEADER]

Thanks Guys for all your support,this is a great site to ba able to access:

[ndchandler]

Dunno if you got it workin or not.....

I had a RTAA300 doing the same thing on one of the circuits. Check the temp sensors. Mine were close, but when the approached setpoint temps were like 5 degrees and circuit locked out on low evap temp.

My RTAA had to run a while after start up before it would do this.

[nlp]

Had one doing this and low oil. only when outside temp changes. Never had any training on it, man. says clean coils and the charge was wrong. I said dirty oil filter. After several days of many people scratching heads. I pumped machine down changed filter ( man. said filter should never need changing ) Unit has been running fine for 2 years. Oh yea man. said other side slide valve was bad filter also.

[Chiller Guy]

Check the thermistors for proper values/readings. If in doubt strap a thermistor on the suction line (10,000 ohm @77 degrees F) and temporarly wire it in for a check. That is pretty much the standard sensor all over that machine.