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Rational SCC Oven Burner Blower Issue
I work in-house and, among some very diverse equipment, I also maintain twenty-one Rational ovens. Twelve are relatively newer SCC-line units and seven of those are gas heated.
On separate occasions, two of our ovens began displaying RESET GAS. One was very persistent and wouldn’t heat in one of its two modes (STEAM or AIR). I found and fixed the problem, which I’ll allude to below.
The other oven’s problem was very intermittent. Function testing it the DIAGNOSTICS panel would only zoom in on which heating mode had the problem, but that was it. The oven would do everything as advertised and I’d simply have to tell them “Call me if it acts up again.” So it’d be fine for a day or two, then all of a sudden it just WOULDN’T. FINALLY – I once again did some function testing and found the problem.
While function testing the burners and noting their sequence of events, I noticed one burner’s blower motor would ramp up to speed (RPM displayed on control panel), then arbitrarily drop out. Through several test cycles, there was no consistency in that event. Sometimes it’d stay running and sometimes it wouldn’t come on at all.
In doing some testing, the ignition module (which also controls the blower) appeared to be doing everything right. I got down to scrutinizing the burner blower and its connections when…AHHH…the wires going into the motor’s connector…fell out in my HANDS!
Here’s a photo of the connectors I’m talking about. On floor model units, there are TWO hot air heat exchangers, so the will be THREE burner blowers:
Those are each five pin connectors with three wires to connect to the burner blowers – AND are a cheesy setup. The plugs are assembled similarly to quick-splice connectors (pictured below) that don’t require stripping the wires. I refuse to use that type of wire splice as it is, so having a factory connector which assembles that way on a high end combi-oven is a bit disappointing.
The blower leads themselves are already smaller gauge wires and I’ve discovered that vibration from the motor eventually causes the connector to gnaw its way through the wire strands one at a time. If this is happening, ultimately the blower will begin working intermittently or not at all – although the wires may appear intact while looking at the plug.
So, if you happen to notice that a blower isn’t running or it sporadically stops running, carefully mark each wire so you remember where they go – j-u-s-t in case. THEN – give those wires each a gentle tug. You might find one (or all three) will drop right out of connector.
If those wire connections are falling apart in your hands, don’t despair for not having another wire harness on your truck. à° _à°
With a little study of the plug, you’ll find that after unhitching a few locking tabs, the connector can be pried apart (an inner section will slide out of the outer section) far enough to open it up. Remove any remnants of the old wire strands and insulation, then lay the marked and freshly trimmed leads back in there in their assigned locations and compress the plug back together. The act of compressing the connector together will complete the connection – just like those dastardly wire splices I’d mentioned earlier.
If you happen be called to work on an oven on which those wires have already “taken the leap” out of the connector, carefully study upon the OTHER burner blower’s wiring. It’s wired the same way, so it can serve as your wiring diagram.
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14 Replies
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Personally, I would have thought of using a soldering iron and heat shrink tubing. Contact grease is also included with most blowers now in the direct factory pack. The wires are numbered on the rational wiring diagram and I would note the alteration. So long as the diagram is still in the plastic bag in the unit or hasn’t fallen down unto the abyss below the front control. I’ve found the diagram resting on the spray roller a couple times. rational-online.com, if you have a user account has quite the vast volume of information regarding these issues including many issues resolved. They also tend to resolve them quickly.
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You bring up some great points. I’ve only dealt with these Rationals for three years now and it sure seems we had a LOGIN ID and PASSWORD for their website when I hired on. Somehow it got lost between someone else being the duty expert and then up to my taking the helm when that other guy left without so much as a “See Ya!”. Along with Rational’s website changes over the past year, I’ve wondered where that info LOGIN went and whether there’s still exclusive access for tech data. I’ should look into re-establishing that resource.
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Insofar as my original post is concerned, I was merely bringing a trending problem to light. Our property has eleven (or twelve…I can’t remember) SCCs. Three electrics (for sure) and the rest being gas. Our use of those ovens tends to be a good, central testing ground for their durability and exposure to their inherent problems.
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Those wires I’d referred to AREN’T marked, Their just WHITE and terminate into two different styles of connectors at each end. But as you said, if the wires come loose, the wiring diagram could be referenced with regard to their connector pin numbers. I haven’t looked to see how clearly those connectors are marked, but most types of connectors (Molex, SMT, etc.) require a magnifying glass (for me) to make out their raised numbering. In the case of this little ole foot-and-half-long or so wiring harness running from the ignition module to the motor, luckily there will be another identical harness there operating another burner that can offer a quick reference. There’s two burners on stand-mounted units and three on floor-units, so the extra wiring harness is there for the referencing.
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Lastly, I sorta snickered at your comment regarding wiring diagrams in the units. Even in-house, they’re not all there (I might work on replenishing them, now that you mention it).
Not too long ago, I was weeding through our three tech training CDs (C-Line, CPC-Line & SCC-Line of Rationals) to put just the diagrams WE need as immediate access onto our shop’s computer and also as a hard copy of each. As I’d said before, they’re primarily not in the units…and accessing them on CD is a headache. We don’t need anything in Espanol, Francais, Italiano, Deutsch or German. We don’t need diagrams for the MANY circuit configurations in which they’re offered internationally.
So during my weeding through the CDs, I found their list of SCC-Line diagrams ALONE (including CMs) has 741 different diagrams to cover those m-a-n-y circuit configurations.
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I only needed FIVE...and THAT gave me a headache. I can’t imagine what their tech support has to deal with.
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Oh…as a side note. You’d mentioned contact grease. Other names for that are dielectric or marine grease.
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I believe Rational DOES provide a little dallop-packet of that for connections made with RJ45 connector cables (looks like a large phone jack connector) which is an ethernet cable. However, they appear to prescribe limiting that only for the RJ45 connections. The convection blower motor uses RJ45 connections. I don’t know if they condone its usage on ALL pin connectors, but I don’t see any problems with it myself.
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FWIW, I have several cans of marine grease that I’d ordered awhile back for use on Frymaster fryer Molex connections.
We have the dreaded NIGHT-CLEANERS who populate our kitchens in the wee hours of the morning to liberally (and ignorantly) spray harsh chemicals all over our kitchen equipment in their cleaning endeavors. The connections down there at our many Frymaster unit’s transformer boxes have failed many times due to those chemical’s corrosive affects.
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Being weary of having to constantly fiddle with failed fryers for that reason, I started using the marine grease on all the Molex connectors in Frymaster fryers. It’s been some time now since we’ve had any problems with those fryers.
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So I guess this was my testimonial for the benefits of contact grease.
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I use only a small amount included in the packet so it lasts me quite a while. We have iPad Air’s and iPhone 5S’ so we store a lot of data in the cloud. Personally I use a Note 3 because its better for signatures and its bloody fast. So how that is relevant is that my google drive contains all the model and serials for said locations and relevant parts manuals and notes related to the piece of equipment. Its very simple to pull up a wiring diagram or find the part number.
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Contact grease was an amazing invention. I will let the other tech’s know what you have found. Not everyone of them is tech literate in regards to computers but as the younger people come in; its a great resource for them to learn quickly without calling me for what they should do. Rational is a hardcore piece of machinery and we don’t let amateurs touch them generally other than a descale. The night cleaners i’ve actually trained in a couple locations so that they understand what they are dealing with. The department heads know how much mistakes cost. The cooks on the other hand dont care at all. I’ve had a spray wand ripped out of its mount and cover everything with water on a SCC 202G. It cost thousands of dollars to repair.
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>RJ45 connections
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Well you won’t have that connector for long.
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Have you seen the new molex style network cables used on the -we units yet?
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Good to see you here, Bad Bozo!
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No, haven’t seen the -WE units…nor 5 Senses (are they different?). Just the original SCC-line. I hope they’re reliable. I’ve not had any issues with our older SCCs with the RJ45s yet.
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no i havent
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No you haven’t…what?
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I’m guessing he has not seen the new molex style connectors?Â
Or the general forum etiquette of necroing old posts. Ah well. I’m glad someone is reading back into the archive in any case. -
Is the connector a molex? with open tube
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