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SCS 2702 basement air rebuild
#11

(08-09-2026, 01:05 PM)whited44 Wrote:  So I was able to temporarily hook this up and test it today. However only 1 of the compressors is running. 

I’ve attached a diagram for some diagnostics help.

On compressor 1 on the control board the black wire goes to the right side of the capacitor 

And compressor 2 on the control board the yellow wire goes to the left side of the capacitor.

Could compressor 2 wire be on the wrong side of the capacitor??  I wired it the same way as I took it apart with all new capacitors.

Here is the wiring diagram from my unit, hopefully its the same:
   

Jeff LoGiudice
Temple Terrace, Fl & Loudon & Monterey, TN
1984 Bluebird Wanderlodge PT40
1998 Newell 2000 #490
1986 MCI/TMC 102A3 (sold)
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#12

(08-09-2026, 03:03 PM)[email protected] Wrote:  
(08-09-2026, 01:05 PM)whited44 Wrote:  So I was able to temporarily hook this up and test it today. However only 1 of the compressors is running. 

I’ve attached a diagram for some diagnostics help.

On compressor 1 on the control board the black wire goes to the right side of the capacitor 

And compressor 2 on the control board the yellow wire goes to the left side of the capacitor.

Could compressor 2 wire be on the wrong side of the capacitor??  I wired it the same way as I took it apart with all new capacitors.

Here is the wiring diagram from my unit, hopefully its the same:

It appears that it’s wired correctly unless the wires on the capacitor need to be on a specific side of the capacitor??  Or does it not matter one side or the other

Also does the board need 2 grounds one for each compressor?? Or does it share a ground meaning of one is hooked up it’s good to go??

Dennis White
1997 Newell Coach 454
Canfield OH
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#13

Dennis use the compressor that is operating as a guide to wiring the one that is not. There should be no difference between them. Also make sure the thermal overload hasn't popped or gone bad, disconnect the black lead and use your multimeter to read across the thermal overload you should read 0 ohms. If all is ok then swap compressor 1 and 2 and see if it fires off, if so then its the control board not calling for it to come on or some compnet that has failed ie fuse, breaker or relay.

1999 45'  #504 "Magnolia"
Gravette, Arkansas
1996 40 XL Prevost Marathon 
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#14

To me it looks like your compressors are wired differently. one cap is going to the start windings, one is going to the run windings.  the compressors have 3 wires  c common  r run s start  the are usually marked on the compressor or in the plastic cover,  one line goes to common on the compressor, ( should be neutral  but either one will work) the other line goes to one side of the run capacitor ( should be the identified side of the cap which plates are closer to the case so if it shorts out it will blow the fuse, but it will work either way) the other side of the cap goes to the start windings, the hard start kit goes across the run cap, I have found that the biggest hard start kit that I can put on that compressor works best, if i have a kit that goes from 1/4 to 1 hp or one that goes from 1 to 3 hp I have found that the one from will 1 to 3 might work when the one from 1/4 to 1 might not, so I always put the biggest one I can on.

John Kosir
712 2004  45-8
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#15

(08-10-2026, 04:06 AM)Jack Houpe Wrote:  Dennis use the compressor that is operating as a guide to wiring the one that is not. There should be no difference between them. Also make sure the thermal overload hasn't popped or gone bad, disconnect the black lead and use your multimeter to read across the thermal overload you should read 0 ohms. If all is ok then swap compressor 1 and 2 and see if it fires off, if so then its the control board not calling for it to come on or some compnet that has failed ie fuse, breaker or relay.

Do you happen to have a link or part number to the thermal overloads??  Are they available??

I'm going to wire the non working one same as the working one exactly even though I think it's that way already
I think swapping 1 with 2 is a great idea.

Dennis White
1997 Newell Coach 454
Canfield OH
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#16

They are generally located on the compressor where the terminals go into the housing. Best thing to do is to read it out with an ohm meter first and see if it is defective.

1999 45'  #504 "Magnolia"
Gravette, Arkansas
1996 40 XL Prevost Marathon 
Reply
#17

(08-09-2026, 04:22 PM)whited44 Wrote:  
(08-09-2026, 03:03 PM)[email protected] Wrote:  
(08-09-2026, 01:05 PM)whited44 Wrote:  So I was able to temporarily hook this up and test it today. However only 1 of the compressors is running. 

I’ve attached a diagram for some diagnostics help.

On compressor 1 on the control board the black wire goes to the right side of the capacitor 

And compressor 2 on the control board the yellow wire goes to the left side of the capacitor.

Could compressor 2 wire be on the wrong side of the capacitor??  I wired it the same way as I took it apart with all new capacitors.

Here is the wiring diagram from my unit, hopefully its the same:

It appears that it’s wired correctly unless the wires on the capacitor need to be on a specific side of the capacitor??  Or does it not matter one side or the other

Also does the board need 2 grounds one for each compressor??  Or does it share a ground meaning of one is hooked up it’s good to go??

The ground should not affect the motor running however the board may use it, not sure. You could use you meter to see if you have continuity connecting the grounds. I am trying to remember if mine had both of the grounds hooked up to the board or not but cannot remember to tell you the truth.

Jeff LoGiudice
Temple Terrace, Fl & Loudon & Monterey, TN
1984 Bluebird Wanderlodge PT40
1998 Newell 2000 #490
1986 MCI/TMC 102A3 (sold)
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#18

Well I think this was my problem. The wire came off of the terminal on the compressor I have some new flag terminals ordered. The other compressor looks like it could use a new terminal too

Ohms all read zero on the thermal overload and between all terminals on the compressor so they all have continuity.


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Dennis White
1997 Newell Coach 454
Canfield OH
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#19

(08-10-2026, 05:30 PM)whited44 Wrote:  Well I think this was my problem. The wire came off of the terminal on the compressor I have some new flag terminals ordered. The other compressor looks like it could use a new terminal too

Ohms all read zero on the thermal overload and between all terminals on the compressor so they all have continuity.

I have used these to fix the compressor terminals before, they work great:
https://www.supplyhouse.com/Qwik-Product...NvEALw_wcB

Jeff LoGiudice
Temple Terrace, Fl & Loudon & Monterey, TN
1984 Bluebird Wanderlodge PT40
1998 Newell 2000 #490
1986 MCI/TMC 102A3 (sold)
Reply
#20

Good find! This has been a problem for some time. 

You can drill a hole use a terminal and use a brass screw and nut. I would wire wheel them to see the brass shine first then put some of this on them.

https://www.amazon.com/gp/aw/d/B0D6R543V...c219e&th=1

I use this on all my electrical connections most certainly on battery connections.

1999 45'  #504 "Magnolia"
Gravette, Arkansas
1996 40 XL Prevost Marathon 
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