scs thermostat manual - Printable Version
+- Newell Gurus (https://newellgurus.com)
+-- Forum: Technical Discussions (https://newellgurus.com/forumdisplay.php?fid=3)
+--- Forum: Air Conditioning (https://newellgurus.com/forumdisplay.php?fid=8)
+--- Thread: scs thermostat manual (/showthread.php?tid=173)
+- Newell Gurus (https://newellgurus.com)
+-- Forum: Technical Discussions (https://newellgurus.com/forumdisplay.php?fid=3)
+--- Forum: Air Conditioning (https://newellgurus.com/forumdisplay.php?fid=8)
+--- Thread: scs thermostat manual (/showthread.php?tid=173)
RE: scs thermostat manual - Wanderman - 08-21-2021
Just took a trip down to the coach and took a look at the rear house electric panel. I noticed there was an extra box with 2 110v romex leads going into it labeled A/C #1 and A/C #2. Inside the box is a contactor. If you recall from a previous message my AC breakers 1, 2 and 3 are mislabeled in on the panel cover.
I wonder why this box is in here? Anyone else have one? And where is #3? Is A/C #1 the front and #2 the back or vice versa? If so why only 2 leads when there are 3 breakers listed for AC.. I know one is a dual compressor (the back one) and the front is a single.
Hmmmm
RE: scs thermostat manual - Wanderman - 08-21-2021
Also, anyone know what the start and run capacitors used are? I may as well replace them at this point.
There's also a "start assist" tiny black one, not sure if it's worth replacing.
I am REALLY hoping the fan motors and compressor aren't seized.
Did find a company that will rebuild this board, if I can't. Assuming that's the issue. Sure seems like no 120v power to anything past the board.
RE: scs thermostat manual - Richard - 08-26-2021
Rick,
Any update on the AC measurements now that you have a working tstat?
RE: scs thermostat manual - Wanderman - 08-26-2021
Not yet Richard...between the rain and work I haven't had any time to get underneath there. Today was brutal outside 100deg and crazy high humidity. Supposed to get a break in a day or two.
It's high on my priority list!
RE: scs thermostat manual - Wanderman - 06-29-2022
OK so the Front AC saga continues. Today I got underneath and tested the board and components. The board is bad. Removed and examined...the traces are cooked. I will rework that for a spare. Swapped in a known working board, and two new capacitors. Immediately I can turn on the FAN (AUTO/FAN switch to ON) and it works! I can also vary the speed with the HI/LO Fan switch.
Now the odd news. Setting FAN to AUTO and either speed, moving the main switch to COOL and making sure the thermostat is set many degrees cooler than the displayed room temp...does NOTHING. No fan, no compressor, nada.
With Richard's excellent instructions I tested the thermostat by bypassing various functions and testing the compressor by jumping 12V power (RED) to the YELLOW (Y1) wire. Immediately the compressor fires up and with the fan in the ON position I get great cooling...the AC works!
This is a brand new RV Coleman mach two stage thermostat sold to me by NEWELL as a direct replacement. I have the same on on the rear Dual Compressor SCS2702.
I checked and rechecked the wiring as the colors change between the SCS harness and the thermostat.
Only thing I can think of at this point is Newell sold me a bad thermostat(?)
Any other ideas before I call and complain
RE: scs thermostat manual - Richard - 06-30-2022
There can be up to a five minute delay before the Tstat tells the board to activate. The delay is built in to keep you from short cycling the compressor.
If you suspect the Tstat, put it on the bench, feed 12V to it, and measure the outputs of the different functions with the meter. The point is to isolate the Tstat from the board in diagnosing the issue.
RE: scs thermostat manual - Wanderman - 06-30-2022
Richard,
I will test the Y1 output from the tstat today, but sending 12V to the Y1 wire leading down to the new board starts the compressor without a problem. I waited MANY more than five minutes as well.
I don't recall whether, when set to AUTO, the circulation fan starts immediately and then after the delay the compressor kicks in. I am also unsure whether there are 2 fans On fore the condenser and one for the circulation since the board only has the 3 connector one for the circulation fan and the compressor connector. Only other external wiring is power in and the tstat.
At least i have cold air and "normal AC amp loads all around.
Rick
RE: scs thermostat manual - Richard - 06-30-2022
Some of the newer Tstats have a freeze protection feature. IIRC, it’s two additional black wires. Since the SCS units don’t have that, those wires must be tied together for the compressor to come on.
RE: scs thermostat manual - Wanderman - 06-30-2022
Richard,
GENIUS! Instant fix. the two GRAY wires for the freeze protection circuit on the tstat from Newell allowed the compressor and auto functions to, umm, function! I now have 8.8amp draw with fan on low 59 degree air flowing nicely into the salon.
I cannot thank you enough!!
Rock On!
RE: scs thermostat manual - SouthernDevGirl - 10-28-2022
I stumbled on this post while searching for something related and I have a quick question / suggestion...
I've never used a thermostat that doesn't simply close a circuit on the hot/cold signal line, once the temp-threshold is crossed. For this reason, typically any "dumb" thermostat should always be able to replace an existing thermostat, no matter how proprietary or odd the original appears to be. This goes for RV units as well (with the exception of the thermostats that have the multi-zone controllers built-in, those typically use serial communications or other approaches).
I'd assume that someone has already tested the existing circuits for continuity by crossing the temperature thresholds to pin-out the wiring; however, I don't see that mentioned here.
Has anyone tested the continuity on pins and moved the temperature thresholds, to determine if your thermostats can be replaced with generic $20 units from Amazon?