Using the Tech Sheet Schematic to Root Out Appliance Gremlins
tech sheet schematic troubleshooting
If you don't have much experience using schematics to solve problems, this article will give you some good, practical foundational information that'll help bring you up to speed. This won't be a theoretical primer on basic electricity and making electrical measurements-- I expect most of you reading this already have that-- nawsir, we's just gonna jump right into real-world appliance problems and get stuff fixed using schematic diagrams.
In this excursion into Appliantological Excellence, we're going to review three recent service calls I did on two refrigerators and a front load washer where I used the tech sheet schematic to ruthlessly hunt down the troublesome gremlins and terminate them with extreme prejudice. In all three cases, you'll see the actual schematics used and how they were crucial to planning and executing my victorious assault.
Fixing A No-Drum Movement Problem In A Frigidaire Front-Load Washing Machine
We've all been on the no-spin complaints in these Frigidaire front load washers. As long as the drum moves during tumble, you know with 98.76% certainty that the problem is a bad door lock assembly, like in this case. Easy repair, badda-bing, badda-boom, skip n' pluck to the next job and life is good.
But what about the case where the drum isn't moving at all, no tumble, no spin, no nuttin'? Could be a bad motor control board. Could be a bad motor. Could be a bad wire connection. Could be lotsa things. But when we're on a service call, "could be's" don't do us any good; we need to slam-dunk, dead-nutz KNOW what the problem is. After all, ain't that why we professional Appliantologists makes the big money?
This video shows that sometimes finding the problem is just as much about finding voltage where it shouldn't be as much as it is about finding voltage where it should be. Using the schematic and ladder diagram on the tech sheet, I was able to prove that the problem was the motor control board because it was backfeeding 120vac to the pressure switch. Something had shorted on that board and it was toast. This justified the huge PITA of pulling this stack unit out of the closet in which it was installed (in a kitchen with new hardwood floors, no less!) to install the new board. And problem solved.
Fixing A Whirlpool Refrigerator That Intermittently Warms Up
This unit is the one with the small ADC board and mechanical cold control in the fresh food compartment control panel. It was intermittently warming up for randomly-varying lengths of time. A really tricky problem, this is one you need to catch in the act to effectively troubleshoot. In fact, I had already been out on this one two days prior to this call for the same complaint and could not find the problem since both compartments were cooling just fine when I arrived. The second time she called back, I got right out and caught this tricky bugger in the act.
Having two things bad at the same time on any one appliance is rare but it does happen and you have to be thorough and persistent to root out all the evil-doers. In this case, both the ADC board and the compressor start relay were bad.
Fixing a No-Cool Problem in a GE Side-by-Side Refrigerator
In this problem, the complaint was that the fresh food compartment was warm. A quick check in the freezer revealed that the evaporator fan motor wasn't running. Rather than tear apart the freezer right away, it's much easier on these refrigerators with a muthaboard in back to just go around behind the unit and do some quick checks right at the muthaboard to see if its sending voltage to the fan.
This is a case, also, where the original minimanual supplied with the unit was AWOL (as in gone) and I was using the copy that I had pre-loaded onto my Kindle Fire just in case. Having been burned like this before, I now always try to load the tech sheet, Fast Track manual, or minimanual onto my Kindle Fire before I run a service call on a unit. So in this video, you'll see me using the schematic on my Kindle Fire.
The lesson on this one is to expect the unexpected and don't get so caught up in the schematic that you overlook the simple things, like loose or unplugged wire harness connectors!
What's It All Mean, Seymour?
Using the schematic diagrams to troubleshoot electrical problems in appliances is not optional unless it's a very simple circuit or there's something visually burnt or disconnected. Knowing how to use the schematic can take away the guess work when trying to figure out which part to replace. The most authoritative schematic to use is the one that's on the tech sheet that came with the appliance. It supersedes the schematics in the service manual because there may have been late production revisions on that model that aren't reflected in the service manual schematics.
But don't count on the tech sheet to still be there with the appliance when you need it! About a third of the time I go out on service calls, the tech sheet is missing; either it was stolen by the sleaze bag who worked on the unit before me or the customer removed it for "safe keeping"... and then lost it. So always try to have the tech sheet for the model you're working on pre-loaded on your Kindle Fire, iPad or whatever tablet you use for storing and carrying technical documents on service calls before you run the call.
If you're not using some type of tablet computer as an information tool, you're really shooting yourself in the foot. You can buy a Kindle Fire for a little as $160! If you can't afford that for a bidness information tool, then there's something wrong with how you're pricing your service and you need to start using the Appliance Blue Book.
And if you'd like to see more videos like the ones in this article, subscribe to my YouTube channel! I'm usually filming these while literally single-handedly whuppin' up on some appliance bootay, so what they lack in production value they make up with edge-of-your seat excitement of live appliance repair action!
- DurhamAppliance, RedToryTy, Wingerman and 1 other like this