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SCS Basement AC tripping breakers
#1
Hi all,

Looking for some advice for a friend with a 98 Vantare that has a SCS basement unit along with 2 separate CruisAirs with SMX controllers...never heard of this setup before...
Anyway....he is having an issue that I would like to help resolve with your collective help.

The basement air starts and runs fine for about 10 minutes and then it trips the breakers. What would cause that and when to start the investigation to address this problem ? He says that unit would put out cold air fine and sometimes run for 15-20 min then trip the breakers and sometimes as short as 10 min. Must be a amp surge somewhere inside......

Any thoughts ?
Marius
1997 #440
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#2
Bad capacitor?
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#3
Others may offer better advice...but I will tell you where I would start.

I am not familiar with the cruise-airs or the SMX controller, but I would start by trying to isolate the components.

On the SCS, there is a wiring diagram inside the cover that covers the wiring. This diagram will show you where the two plugs are that control the compressors. Once you find the compressor wiring...use a clamp on ammeter to figure out what the amp draw is. There are other posts on the forum that will tell you how many amps are normal, but I remember something like 15 on one and 13 on the other.

Understanding the amp draw is the first step to figuring out a breaker issue.

In my case, I had a strange case where the AC wire that fed the SCS unit was shorted somewhere that I could not get to. The solution was to run a new wire back to the breaker box. (This was a very unusual situation but it was easy to find since my units were drawing a normal amount of current before the breaker tripped).

Bill
Bill Johnson
2003 Newell #653 Quad Slide Cat C-12 engine with Motorcycle lift 
2011 Jeep Wrangler, 2018 BMW 1200GS Adventure Motorcycle
Auburn, Alabama
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#4
I agree with Bill. Pull the access cover for the circuit board on the SCS. Look at the schematic printed on the back of the access panel. Put clamp on ammeter on each compressor, and also the evaporator and condenser blower motors. The compressors should be pulling 11 to 14 amps depending on outside temps. Each blower motor should pull around 2 amps.

A question to ask about the shutdown is, does the inside or outside blower motor quit before the breaker trips? reason being is tha either motor shutting down while the compressor is running will cause high head pressure in the compressor causing high amperage draw.

You could have a bad capacitor for either compressor or blower motor.

You could also have a compressor heading to failure. I have had one compressor failure in the SCS units and the early warning signs were sporadic breaker trips.
Richard and Rhonda Entrekin
99 Newell, 512
Subaru Outback Toad
Inverness, FL (when we're home Cool )
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#5
Are the SCS's same as the older RVAC units?

When we got our coach both of the boards were stripped of the units and they were just being used for the blower motors.
I had a high school friend of mine wire it all up "mechanically" with just capacitors, relays, and timers, works like a charm.
1996 45' Coach 409      Formally owned by a rock star.

60 Series DDEC III, tuned, No Limit Manifold, S475 turbo and Fluidampr

Purchased wrecked, currently redoing all interior and RF wreck damage.
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#6
I thank you all for good leads. Will tell him what you all suggested and hope he gets to the bottom of it.
If not, he is passing with the bus through northern Indiana early July and I'll take another look at it.
Marius
1997 #440
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