Help wiring a dual compressor condensing unit.

[Okolowicz]

If there are any A/C experts here, I am in need of some help. I have a Rheem RASL-048JEC condensing unit which has two compressors. Each compressor is controlled by its own board and each board has a Y1 and Y2 connection point.

I know the Y1 and Y2 from inside house needs to go to the Y1 and Y2 on the condensing unit. However, I'm confused because there are two Y1 and Y2 points on the outside unit (1 for each compressor).

Here are the options:
1) Connect the Y1 from inside (t-stat and air handler) to compressor #1 and Y2 from inside to compressor #2

2) Connect Y1 from inside to Y1 on both compressors and Y2 from inside to Y2 on both compressors

3) Something different

Thanks

 

[Ohmthis]

Looking at the diagram, they should be wires (factory installed) off of one board that should go down to where the line (power) and 24v go. From there you would wire nut the wires. we need to know which air handler/furnace you have to see the inside connections. But here are the wire colors.
From Inside Outside unit
R (red) Red
C (common usually blue). Brown
L (need more info) White w/red
Y1 (compressor yellow). Yellow
Y2 (compressor 2). Yellow w/ blue
1 (need more info). Yellow w/ pink
2 (need more info). Orange w/ white
Give us the air handler or furnace info and we can help farther.

 

[bonneyman]

Worked on a Trane two-compressor unit 2 weeks ago. It had to have a signal on both low and high speed to get the unit to come on "high".

Strange bird.

 

[bonneyman]

OK, just happened to find some on-line product sheets. Looks like the unit runs on first compressor (50% capacity) most of the time and then the second compressor comes on when it's really hot. They appear to be in tandem (sharing the same line set) so, I'm assuming there are two 2-ton compressors.

Maybe you'll find something that will help here.

http://cdn.globalimageserver.com/fetchdocument-rh.aspx?name=rasl-jec-specification-sheets

 

[Ohmthis]

Yes, that is how they work, I believe your L wire may be the signal and 1 and 2 wires are for solenoids. Do you have any info on the air handler? That would be helpful to us.

 

[Okolowicz]

Condenser is a Rheem RASL-048JEC
Air Handler is a Rheem RHPNHM4824JC

Thank You!

The manual makes it seem pretty straightforward to rewire the air-handler for a conventional t-stat. I've already run new wire from t-stat to air handler (replaced 18/4 with 18/7).The air handler connection points are well marked as is the new t-stat, so I don't think I'll have any issues. Outside is another story. I'm assuming the Red (R) wire and Common (C) wire will stay exactly where they are. The Y1 and Y2 are where I'm stuck.

I know they need to be connected but can't tell which compressor they need to be attached to. Here is a link to download the wiring diagram:
https://dl.dropboxusercontent.com/u/4716709/diagram 1.pdf

 

[bonneyman]

The Trane unit I worked on earlier with the two compressors were 3 tons and 5 tons, respectively. And only one compressor runs at a time. Three tons for low, five tons for high. (Unlike this Rheem unit where both comps run for high). But both compressors shared piping and oil return. Which meant if one comp burns out it takes the other one out with it.

From the on-line material I can't tell if that applies to the Rheem duo as well

 

[Okolowicz]

bonneyman,

Assuming I did it correctly, you helped me figure it out. While the manual was confusing, looking more closely at the wiring in the condenser it appears the two compressors are already wired to run in tandem. It appears all i needed to do was connect the Y1 and Y2 (from t-stat and air handler) to the Y1 and Y2 on "Compressor A." I made no connection to Compressor B. It is definitely cooling the house well.

Is there a way to test that that each compressor is working as it should?

Lastly, the manual is confusing regarding the dip switches. If someone could provide any insight, I'd be grateful.