STC-1000 Question/Help

[brodach]

So I'm building my first Keezer. I picked up an Igloo FRF1050 (10.7CU) and purchased an STC-1000 to get things started. I decided to "hard wire" the temperature control in place of the stock control because I really like the aesthetics of that setup.

I analyzed every possible diagram I found on these forums just to make sure I knew what I was doing, and wiring it wasn't that difficult -- so I thought...

So the STC-1000 powers up, reads the temperature, flashes the "cooling" light as it waits for the delay -- upon the end of the delay, the cooling light goes solid, aaaaand nothing happens. The compressor doesn't kick on -- I don't even hear the relay click (I tried to wire up the heating side to trick the compressor to turning on from that relay, but it too would not). I haven't had a chance to test anything with a multimeter or anything, but hopefully I can get that done soon.

I'll try and add some pictures tonight -- I only have a couple on my phone right now.

Since I cannot add many useful pictures right now I'll try and describe everything, and maybe draw a picture. The unit is an STC-1000. 1&2 are power supply, 3&4 are probe, 5&6 are heating, and 7&8 are cooling.

I ran the hot wire from the power cord to 1 and jumpered it to 7. I attached neutral from the power cord, to the neutral leading to the compressor, and then attached that to 2. I then attached hot leading to the compressor, to 8 on the STC-1000. The unit powers on, but never powers the compressor. As I mentioned, I never even hear the relay click when the delay ends -- so I'm wondering if I got a defective unit. One thing I did notice, is that my freezer uses 20 startup amps -- but from the get-go the unit didn't seem like it even made an attempt to startup the compressor.

Has anyone else every encountered this? Could my unit be defective?

Some pictures from the back of the freezer:

And here is my amazing drawing of how I wired the STC-1000:

From my understanding, this should work. If I remove the STC-1000 from the mix, and just directly reconnect the hot and neutral wires from wall cord to compressor, it starts the compressor right up, so the connection is there, I'm just not sure what I'm doing wrong, if anything. Or if the STC-1000 is bad (I figured I should be able to hear those relays).

Any possible input would be greatly appreciated.

Thanks

 

[MrFoodScientist]

Did you cut out the existing thermostat? If you can't hear the relay click, I would guess that's your problem. It looks like the same way I wired mine. It's strange that you would have a defective unit with both the relays defective, though. With the 20 amps, did you toast them?

 

[benzesp]

Looks correct. I'd wire it up out of the freezers circuit on a bench and check the relay functionality. The STC units are cheap, wouldn't surprise me if you had a bad one. The 20A spike concerns me. My 7.5 CuFt pulls 8ish amps when it Kicks on. If it is actually pulling over 10A you could damage the relays.

 

[Spellman]

Different stc-1000's have different relays as I've found. I have seen some that only do 5a, there are some that do 10a, and my preference is the ones that are also compatible with the stc-1000+ firmware, which all of mine say 15a. Depending on what you have it may or may not be a concern. I have one running a 5000 btu window ac that near as I can tell draws about 18a+ for an inrush current, then back down to 3 or 4 amps. It has been working great for almost a year now. Many appliances have a steep inrush that they use to sort of kickstart themselves, but only a few seconds of this spike doesn't hurt or damage things as most electrical is based on constant load (as far as I'll go on this can of worms). One thing you could try to circumvent that power would be to use the relay to control the thermostat wire instead of the power. That would be also have the benefit of keeping the warm up and cool down cycles intact on the freezer (theoretically prolonging its life). You could test to see if the relay still works or if it got fried/defective by putting a multimeter and checking for continuity while it is engaged (remove the hot wires to the relay first of coarse!) If you don't have a multimeter, get one, they are awesome and very handy to have. Just google continuity test, I can never remember what setting to put it on. One question, did you wire the stc in before or after the start capacitor? If after it may have fried it.

 

[Bellybuster]

Just for interest, I just recently received 2 stc1000, one of them neither relay works and the other, only the cooling relay works.
The Chinese ebayer promtly refunded my money.

 

[brodach]

Yeah I pulled out the existing thermostat, and sorted out the extra wires that run the multiple lights etc. and got it down to a simplified version. I've so far maintained the stock guts though, in the event that I do need to put the OEM controller back in.

If the relay's were good and got fried upon the first test because of the 20A startup, it wasn't noticeable. No odd sounds, smells, or anything after my initial attachment. I popped the unit opened and visibly there wasn't any damage on the inside. The relays did say they were rated only for 10A right on the relay so that does concern me with the 20A startup.

One thing I did notice when I got the unit, and maybe this is just normal, but there was a really strong smell -- I can't even really describe the smell but it was a really strong odor. Something that would only come from electronics -- not really the smell of anything electrical that had been fried. But regardless, I just found it odd, but dismissed it when the unit turned on -- minus the function of the relays.

As far as the start capacitor, I did wire the unit in before the capacitor. I plan on picking up a multimeter so I can toy around a little bit more this week and check the relay itself, rather than rewiring the unit over and over the same way thinking it will magically work, and then scratching my head. But I'm starting to think more and more that I just ended up with a bad unit. From the very moment I powered the unit up, it made no noise -- other than the beeps it makes when you press the buttons. So if the relays got fried after, they did so very very quietly. After hearing Bellybuster say he got 2 defective units, I'm starting to feel like there is a decent chance mine is a dud too.

Thanks everyone for their input and help. I'll try and check the relays tonight and verify that they are defective, or fried.

 

[peterccann]

Hello, I know this is an older post but did you ever solve this issue? I'm having the same problem right now.