$0 Edgestar Repair AKA the Achilles Tendon Cap (1 Viewer)

[greentruck]

Like many here, I found what I still consider a bargain in the scratch and dent bin of compactappliances.com in the Edgestar FP-430. Crumbling handles and hinges aside, it's been a generally reliable machine...with the occasional exception when it would just lose its mind, seemingly just forgetting what it was up.

Then it just quit...but even then it didn't seem committed to quitting, either. I could plug it into AC and it was fine. I could put it in Fast Freeze and it would take about an hour to go from the mid 70s to 0 F. Nothing wrong with the compressor or sealed system like that. I could then switch to DC and it would hold fairly reliably, except being frozen doesn't work for many things you might put in it. Adjusting to an above-freezing set point would invariably cause it to revert to mocking you by refusing to go or stay there on DC.

Edgestar technical support was even flakier than I remember, but they were eventually proven partially right in terms of which module had the problem...but with no help beyond that. Despite me having seen one on their site within the last week or so, the AC/DC inverter I was said to need (at a cool $148!) was no said to be no longer obtainable!

"Gee, that was 6 years ago and we just quit making parts for that version...although we are selling a new improved version whose parts won't fit yours and we'll give you a 10% discount on a new one @ $699..."

I just wanted my old one to work. This ain't rocket science. I used to deal with Thermoking parts and rub shoulders with our reefer guys in the garage where I used to work.

Plus an AC/DC inverter failure didn't account for it working so well when it did run. Seemed like it should be all or nothing, and would stay that way. Sometimes it just seemed to hang up, with the compressor running for about 10 seconds, then shutting down. That seemed to point more toward the temp control module to me.

Further analysis led me to take apart the AC/DC inverter. I thought if nothing else I could just hack it to straight DC (who needs AC on the mobile fridge if being DC only makes it work?) There is a separate compressor motor controller and I thought the starting circuit with its caps, etc would be in it. Nope, the starting caps appear to be these here.

The starting caps are just above my left index finger, along with a blue box that seems associated. If this box really is not obtainable, hacking it to DC only might save some fridges if they suffer a bigger failure than mine turned out to be. Looking over this area would be the place to start.

This is what the AC/DC inverter box looks like opened up.

I continued looking over the board for signs of failure. Near the right middle edge of the circuit board in the last pic there is a integrated circuit, with a cap standing just to the left of it's left end it as in this pic.

Turning the board over, you find a few surface mount resistors, etc mounted to the underside of the board, along with another lonely cap, the squareish brown one.

What's it doing here? I was thinking some sort of field repair (given it's origin as an open box item) so looked it over carefully. It wasn't, as there was labeling printed there to show it was of factory origin, but I didn't like the looks of some solder that might have a trace of touch against another, so took my Exacto knife to scrape a little to ensure things were definitely not touching. I bumped that cap. Dang if it was actually broken, but with the ends touching -- apparently intermittently!

If you look closely, you can see that the lefthand leg in this pic is actually broken. I used some silver solder to steady it down. This is an obvious weak point, perhaps an after-design add-on to solve a problem discovered in testing. The label is actually printed on the board (C 20 upside down to the right of it.) There's very little clearance between it and the case once the board is installed. Unless clear of the case, it could press and vibrate against the case, potentially causing it to break. Or perhaps bending it over after being soldered in place could be the culprit? Might be worth checking if all else has failed and Edgestar customer service can't or won't help.

Is the fridge totally fixed? It does run down to set temp on DC now with no issues. Once there, it seems to have trouble maintaining the temp. After rising back past the setpoint a couple of degrees, it starts up at each degree after a short interval. The compressor runs for about 10 seconds, then shuts down. Again, seems to be no issues with the sealed system. I can get it to run down to the setpoint if I turn off the power, then turn it back on. Right now I have it headed via FF for zero, where it seems to hold just fine on DC once AC got it there before. DC started down at FF, but then kicked out. I plugged in AC to get it going, the switched back to DC at 40 degrees; now it seems OK with DC doing the heavy lifting.

Anyone have any ideas on this? I think might be the temp control since it seems to try to restart at each degree as it rises and it does run for 10 seconds or so, seemingly normally and well past where it would get without the load being tempered by the starting circuit.

Noted within the AC/DC inverter were a glass 3 amp fuse and a blue pot at the right end under the row of terminals (just to right of green LED visible in first & second pics) that controls the variable DC output. Fuse was OK on ours, but I left the voltage as is.

 

[greentruck]

Doing more testing, so here's some random notes and observations.

There is a green LED next to the blue voltage adjust pot. The LED lights when AC is connected to the unit.

The video I referenced earlier is this one:
It's commented in it that the fan on the AC/DC adaptor/inverter "always runs" or something similar to that effect. That is not correct. The fan does come on during AC operation, probably because of the heat generated by the conversion of AC to DC and this seems controlled by a heat sensor, as it turns on and off automatically. I did not notice it one at all during DC operation, probably because the DC doesn't need converted, just routed to the motor control.

The AC/DC adaptor is made by CZJutai in China. I have an inquiry in to them about getting a suitable adaptor. They tend to ship in container-load quantities of 10,000+ units. Not sure a group buy is a solution here, but will advise what they have to say or if, as I inquired, there are any US importers it can be obtained from since Edgestar refuses to sell current production parts for vague reasons.

Testing right now, fridge is sitting at a slight angle in its tray with the controls mostly pulled out where I can access them via a set of jumpers to give me some elbow room. Set point is 36 F. I had to start it on AC. Switched to DC once it had time to get heat-soaked. Currently at 52 F, down from 74 F to start. After the AC to DC switch, had a weird event, but it is still running. The Low Voltage light came on when it started on DC. I'd taken the battery reading (it runs off the primary) at about 12.04 volts, but I've been testing the fridge all day, so that makes sense even though battery is less than 2 years old. The AUX battery was sitting at 12.6~.

After the low voltage warning, I checked DC at the controls. It was down to 10.8 v! Kinda weird, because I've generally got more than sufficient voltage readings when checking it. Strangely, instead of this low voltage triggering another alarm, it just started up and kept running, as if it actually liked low voltage better than 12 volts?!?

At this point I combined the two batteries to try to bring the primary up some. This helped the readings a little on the Edgestar, but the Main was still down about 10.88 v and the AUX read around 12.4 v when combined. The chill is down to 49 F so the cooling continues despite the low voltage. I presume this rules out the intermittent attempts at restarting at every degree as the inside temp rises after pulling down to set point to NOT be due to low voltage (I very rarely see that alarm and the end of the cord reads within 0.01 volts of the battery, so not getting much voltage drop from front to back of truck anyway.)

I plan on letting the unit achieve setpoint (36 F), then see about whether it will hold that temp.

 

[greentruck]

The Edgestar overruns the set point by about 3 degrees (to 33 F in this case) then shuts down. After reading close to 10.7 v while running, the readings at the DC power out from the AC/DC box is 12.25 v with the batteries still combined after shutdown. So the Edgestar seems to put enough of a load on the system to pull the battery down noticeably. This may be contributing to the failures to restart when rising temperatures overrun the setpoint without response.

I noticed two small yellow relays on the board, guessing they may have something to do with the power conversion process. Relays can be a source of trouble...

But I continued to take readings (from the COM and V+ terminals on the Ac/DC adaptor) after getting to the setpoint. As the temp came up, it again tried to restart with each degree. Now I was taking readings that ran as low as 9.71, but generally below 9.8. This is not good. The Low Voltage light NEVER came on, but it was low nonetheless..,.and that caused the motor to drop out and quit as this happened.

Wire to the front is big fat stuff, 10 gauge, guess still not big enough. I do have a fat pair made from an old set of jumper cables that go to the rear inverter, so I may have to tap into that instead and see what happens.

To summarize at this point, I think I fixed what was broken, the cap lead, and solved most of the mysterious behavior it caused. What can't be fixed is the design's excursions into strangely low voltage situations. Factory-supplied wiring is often ridiculously thin and that potentially reflects badly on this already sensitive device.

 

[e9999]

I'll admit I didn't try to go carefully through all of the above but you seem to be dealing with low voltages. Have you tried to run it off a power supply that ensures a voltage at the source well above the cutoff point when running? Or at least run the fridge with the engine on if you are running it off the truck battery? So you can eliminate the possibility of low voltage / voltage cutoff issues.

 

[greentruck]

I'm sure that would help, but it's not the solution I was moving towards. Complicating the picture is my CPAP. That's what the AUX battery is dedicated to, otherwise I'd stick the fridge on it.

I've already checked that I have a good short cord, 5' section with a PowerPoles on each end. I'll know after I install that on the rear inverter if it's solved the problem.

 

[greentruck]

...and, YES!, the short, fat new cord I made from the PowerPoles #8 lines, tapped onto the inverter feeds, did the trick. The Fp-430 is happily burbling away, stopping then starting again as the temp changes inside.

So a summary of lessons learned when troubleshooting these sometimes ill-trained puppies...

1. Try to eliminate any factors that could create issues. Running down that problematic cap as the source of some of my frustration over the years was my big issue on that front. Similar common problems are loose connections and crowding the unit so there's not enough air flow to it.

2. There is a Low Voltage warning lamp on the control board, but don't trust it. I've been seeing the symptoms of low voltage for years, but assumed the light would let me know, if so. It won't.

3. If all else checks out, the unit pulls down to cool pretty well initially, but then refuses to hold the setpoint by continually trying to restart and failing after a few seconds when the inside temp rises, that's most likely a symptom of low voltage at the unit. Put the unit on 12 volt power and DISCONNECT it from 110 volt power for safety purposes when doing this test. Get your voltmeter out and check the voltage at the COM and V+ terminals you see in the pic below (note the lid is turned upside down in this pic vs the label on the lid.) Counting from the left on the black terminal strip, that's spots 5 (COM) and 6 (V+) on it.

If you get readings that drop to less than 10 volts when the motor is trying to restart, low voltage is your most likely diagnosis as the problem.

Despite knowing this about the Edgestar, I thought my wiring was adequate (#10). My power cord wasn't really any longer than the factory one. I did have a switch to turn power on and off. It all added up to too much voltage drop. If you can't navigate a multimeter or don't want to dig in to your unit, then get a power lead much closer to the battery and try that on a test basis. If it runs fine then, you've also found the issue that way.

Another factor is as batteries age, they tend to hold power at slightly lower voltages. You could have a working Edgestar on your wiring, but six months from now, as the battery ages, it may not, then it's voltage may have dropped below what the Edgestar needs for that reason alone. Something to keep in mind if everything else was equal, except for this sort of symptom.

 

[e9999]

that is why I suggested to eliminate that possibility by checking with higher voltage...
I had the same thing happen a while back. I found my fridge off. Turns out that I had used a slightly too long cord and the battery was low enough that it just reached down to the cutoff point at the fridge entrance with the additional voltage loss.
These units seem to have a fairly high (non-adjustable on mine) cutoff point that voltage losses in the cords may easily bring supply voltage down to. Most people underestimate how big losses can be in small wires. IIRC my 4' or so cord gave me like 1/2V loss. I think I discussed this here someplace.
I suppose a high cutoff point is a nice protection for being able to start the engine in the desert but not so good if your whole food supply got thawed overnight unbeknownst to you. (Why I use a temp alarm in my fridge.)

 

[greentruck]

Thing is, the set-up I was having a problem with worked fine for several years. And there's no place else in the truck to put it. I tend to think of systems, rather than discrete components, especially when it comes to successful systems that develop problems. With my flaky back, best to just leave things in place and bring the test to them.

I'm not sure it's so much a too-high low voltage cutoff as it is a too low low voltage cutoff. I was surprised that the unit still was trying to run below 10 volts, not for long, but it tried as I made sure my results were repeatable. And the Low Voltage light never came on. It came on at several other points, so it's point is not entirely without merit and it was working, it's just not very informative for commonly encountered situations - like the motor pulling down the voltage itself.

 

[e9999]

come to think of it I think I had something similar happen once. Like starting and immediately shutting down. But that would likely be due to the battery voltage going down quickly with the load.

 

[rusty_tlc]

Great info here thanks for posting.