I got a service call to a store with a Trane Voyager series rooftop package unit. The call was for a very loud squeeling noise coming from the unit. I was called out last year for this same problem and after some troubleshooting and some calls to some other service techs, decided that the valves for the number 2 circuit compressor were shot. Unfortunately, I was not the one sent out to replace the compressor. However, the noise stopped after the new compressor was installed. That was last year around june.
Well, I got called out again for noise comming from the same unit. I get on site, make a wild guess that it is the circuit two compressor again, and bam! I've located the noise. Sure enough, it's the circuit two compressor. Crap. I know it is the compressor because I shut everything else off to locate the noise - the cond. fan, the blower fan, the circuit one compressor. The noise starts just as the compressor pressures get up towards 125 discharge. Then it keeps getting louder and louder until you can hear it in the parking lot.
Now, while I'm looking at the compressor, I look back and see that the liquid line filter does not appear to be new. In fact, it still has the trane paint on it and I can't think of one of our techs that has that paint on their truck. I was trying to look at the label to see if it was new or not so I had to stick my head in over the compressors but under the control box. Hidden up behind that is a suction line filter on circuit two. (brazed in, not replaceable core type) and for some reason, it looks brand spankin new.
After a little research, I find out that back in 2004, we had replaced the compressor due to a burnout, and no one had ever followed up with acid tests or removed the suction filter.
I also find out that the tech that replaced this compressor last year for some reason changed the suction filter, but not the liquid line filter.
I know I should've found that suction line filter last year, and that's on me. However, that bastard was hidden pretty damn well. My question is whether or not that suction filter could've been the problem all along. The pressures don't really reflect it, and I haven't been able to find my notes from last year, but here is what I've got this year.
Trane model # YCD150C4HBB , serial # R25104819D, 460 volts, 3 phase.
With both stages running, blower on, and condenser fan running, here are details.
Circ 1, comp amps 6.7, 7.9, 7.6 (10.6 max), press 65/225, ret air 72, sup air 56, superheat at compressor 21 degrees, no subcooling possible
circ 2, comp amps 7.3, 8.2, 7.4 (10.6 max), press 67/240, ret air 72, sup air 46, superheat at compressor 24 degrees, no subcooling possible
I took the supply air readings 15 minutes after stage one on and ten minutes after stage two on (noise was unbearable)
Blower fan and condenser fan rotating correct and amp draws and voltages ok. Voltage for unit is 494, 496, 494