A/C glycol chiller; how to bypass thermostat?

[Ntense]

I built last summer a glycol chiller for my fermenters.

Everything was running fine except now, since the temperature in the brewery is close to 60F, the A/C thermostat won't turn on the compressor (only the fan).

I checked the A/C instrution manual and it's written below 62f the compressor won't turn on...

I tried to remove the thermostat wires from the board and turn on the a/c; but the compressor isn't working.

Is there a way to bypass it?

Thanks for you help.

If pictures are needed, I'll take somes.

 

[mredge73]

You don't remove them, you tie them together.
Should only be 2 wires for a simple thermostat.

 

[Ntense]

thanks for the reply, it's appreciated.

I think it's more a thermistor than a thermostat, but if I take it off and wire both wire, will it work?

I just checked it with a multimeter and resistance is going down when I warm it.

So it would makes sense... what do you think?

 

[JLump]

The thermostat for an AC unit acts like a switch(one that operates on thermal input instead of mechanical input). You should just be able to short the two wires going into the thermostat to bypass it.

 

[JLump]

I think it's more a thermistor than a thermostat

Oh, sorry I didn't see that. If it works off of a thermistor that's a little different but there should still be a way to bypass it. Hard to know without more information. If you could post a picture of something, that would help.

 

[Surfmase]

I removed all of the original controls from mine and wired power directly to the compressor and fan. Both compressor and fan had a capacitor which took a little studying to figure out. I did leave the small overheat sensor on the compressor lead.

 

[mredge73]

Assuming that the resistance lowers as it gets warmer and you have digital controls:
Warm it with your hand up to body temp and measure the resistance.
Go to radio shack or similar electronic store; get a resistor that is slightly higher than the resistance that you just measured. So the warm resistance is 100 ohms, get a 100-150 ohm resistor and some alligator clips.
What you will do is put the new resistor in parallel; clip alligator clips to the exposed leads of the thermistor. The resistance sensed by the control board will now always be lower than your selected resistor.

Why not just jump out the sensor? If the digital control board senses a direct short it may think that the thermistor has failed; this will likely show up as an alarm and shut down the AC.
I would still try it before going through all the trouble with buying a resistor.

Why cannot you just remove the sensor? The digital control board will sense an open condition, infinite resistance. It will either alarm out or think that the room is ice cold.

Can you replace the thermistor with a regular resistor? Absolutely.

 

[Ntense]

So if you tell me that I can replace the thermistor by a resistor that is slightly lower, that's what I'll do.

I also send you a picture of the thermistor and also one from my brewery.

thanks for the replies, it's appreciated.