PHSC39EGSS0 adc jumper

[crawdad]

Can someone tell me what this ADC jumper does? On the board, it says "If open ADC" and on the schematic it says "Defrost Jumper. Open=ADC. Short - Timer. I'm having a no defrost problem and I'm wondering what would happen if I moved the jumper to connect both pins. It seems obvious that it bypasses the ADC and switches to a timer but I'd like to be sure. It's on the main power board # 241511102. I recall one thread here where the pins were shorted together and it solved the problem. Thank you.

 

 

[crawdad]

I would like to add that the bi-metal tested ok but I replaced it anyway. The heater reads 30 ohms. Both sides are cooling ok. Won't go into manual defrost by holding Freezer UP and pressing FF down 5x although "d" and "f" appear in display. It shuts off the cooling but heater doesn't activate and it resumes cooling in 6 minutes. When it goes into auto defrost, I hear a click, cooling shuts down, no heat, and resumes cooling in 6 minutes. The freezer thermistor near the auger motor tested for correct resistance but I only tested it at room temperature.

[Budget Appliance Repair]

I had one of these Frigidaires doing pretty much the exact thing you are describing.

I didn't have another board and the customer didn't want to spend a lot of money so I set that as jumped and they haven't had any defrost problems since then.

Give it a try, can't hurt anything.

[crawdad]

Ok, thanks, I will. I thought it might work, then I thought maybe some fridges got the ADC while others got a separate timer so the motherboard was made to accomodate both. If it works, it will give me the time to figure out the myriad other problems. I'll post about those later. And I'll update this one with the result.

[crawdad]

So the ADC is jumpered. Still operating like before and just waiting to see if it defrosts. I think it was a 4-hour interval before defrosting after a power interruption with the ADC but in "timer" mode, I'm not sure.

[Budget Appliance Repair]

I don't know what the specs are for the timed mode but I would expect them to to similar/close to the standard mechanical defrost timers.     Will most likely defrost every 10 to 12 hours of run time for 20 to 30 minutes.   in the timed mode I don't know if it still sense when the defrost t-stat opens and then start running after it's 6 minute dwell period or if the defrost time of 20 to 30 minutes just runs out like it would on a mechanical timer model.

[crawdad]

Thank you for the info. After my post yesterday, I monitored it as much as possible and never heard it go into defrost on its own nor was there any water in the pan. Before moving the jumper, it did go into defrost on its own, just didn't work. Just now, I tried manual defrost but same result as before: click, heater doesn't heat up at all, six minutes later resumes cooling. I guess I'll do the basic checks again and put the jumper back where it was. Someone said the heater could be bad even if it checks out ok. Is that possible?  Could I just take an extension cord, connect the wires to the heater, then plug it in to see if it glows? Maybe the connections to the heater are corroded. Anyway, I'll stay on it.

[crawdad]

I'm thinking about replacing the heater although it tests ok at 30 ohms. Is it possible that it's still not good?

[Budget Appliance Repair]

No, your heater should be fine.

The more likely problem is a bad defrost t-stat, that's a much more common failure part.

[crawdad]

Ok, thanks. Maybe I got a bad replacement. I've been testing the old one, in and out of the freezer, and it seems to work although I don't know what temps it's opening and closing at. Odd thing is, it had been there for 10 years, working ok, but has a different part # and is 3x the price of the one the part stores show for my fridge.Hard to believe there would be much difference in tstats. Anyway, I did get the one listed for my fridge and may get another.

[BrewHobbyTech]

20 hours ago, Budget Appliance Repair said:

No, your heater should be fine.

The more likely problem is a bad defrost t-stat, that's a much more common failure part.  

"should be fine"......yes, but it may not be, we've all seen strange things out in the field. As soon as I think I've seen everything.....along comes a really oddball occurrence...again. I've come across at least two calrod type heaters in the last couple years, that when I ohmed them out they were fine. Then I'd check it again later and I had no continuity. This is one of those things where you have to go with experience....and trust what you know. Sometimes it does drive you nuts, but you have to believe.......nothing surprises me anymore.....absolutely nothing......  

Here's my advice on this problem.......if in any doubt.....physically remove the defrost heater(and it may be a total pain in the ass(PITA, for future reference)...and it does depend on exactly what piece of crap you're trying to diagnose....because no two pieces of crap are alike........(and....holy crap....us technicians, and/or parts changers certainly recognize that), and obviously disconnect the wires. Ohm it out....and set it down and pick it up multiple times if need be. I've had to jimmy it around to try and make it fail(I don't bend the crap out of it, just move it around some.....and maybe you'll finally get the infinite reading(no continuity) you were looking for....or not. There's only three things involved with the defrost cycle.....the defrost control(either a digital control board or an analog old time timer, which we all still stock on our trucks), the defrost heater, and some sort of sensor or thermostat or cutoff device which ends the defrost cycle. OR.......it could be a bad wire......those can be a nightmare to find......or try to find......

Anyway, if you have any questions to this problem, or any problem.....other than women problems(I have no answers for that.....good luck....), give me a shout......  

 

 

 

[crawdad]

Thank you for your response also, BrewHobby Tech. I'll be defrosting again next week when I should be receiving a new heater. I will remove it, test the new one and replace it. Before I defrosted last night, I checked the tstat continuity - zero - and heater continuity - 30 ohms. Then I checked through the plug from before the tstat and through the heater and got 101 ohms. So some extra resistance there. I then put it into manual defrost, "d" and "f" showed in the display and cooling shut down right away. I had no voltage between the wire feeding the heater and ground.I unplugged the fridge and checked tstat - still zero ohms. I'm going to pull out the motherboard, put it into manual defrost and check voltage from heater to ground.

This is a new motherboard which I got not only for the defrost issue, but I was hoping it might help with the lack of power getting to the whole dispenser and water valves area, including the freezer light and light switch. I've checked the connection at the top of the freezer door, ice maker connections, and the plug that the ice maker connection comes out of. I do get 5V but not 120V. This resulted from when the ice maker caught fire. The water dispenser still worked after that. Then I tried to repair the ice maker wiring, plugged it in, and got quite a nice, loud spark. That caused the water dispenser to stop working. The fridge has cooled and defrosted since then for three years. I mention all this in case it has any relevance. I also have the Apollo lighting control and don't detect any voltage there. I'd like to get to the 12-connection plug that a lot of these power-carrying wires go through but it's behind the compressor so I'll have to lean the fridge back and take out the drip pan which I've done before to check out the Apollo board.

Well, they say everyone has a book in them. I guess that's mine. The priority is defrosting so any help towards that will be appreciated. I'm determined to solve this but when I get tired of weekly defrosting with a heat gun, then I'll call a tech.

[BrewHobbyTech]

While you have everything apart I'd replace the defrost t-stat for good measure. I've had at least two over the years that tested good with my meter but failed with a load, which meant the internal contacts were bad from arcing.  

[crawdad]

Ok, good point, didn't know that. Might as well.

[crawdad]

Going to replace the freezer thermistor too. Might as well. It's the same as the one in the FF section?

[crawdad]

Tested heater today with 120v. It glows red hot at the bottom, around 500 degrees F, and then up about 4 to 5 inches. So, it's glowing hot less than halfway up. Is that working properly? Should I change it out?

[BrewHobbyTech]

The heater is good. 

[crawdad]

Great, thank you.