Override windows air conditioner not working

[augiedoggy]

The unit I used was remote control only, w no remote, I did screw around with bypassing the temp board, but soon realized getting rid of all but the 120V circuit was simplest option. Why rely on all that micro circuitry when it does not even need to be in the loop?

Edit: If the AC unit is to be run by another controller like an inkbird 308, all one needs hooked up is compressor, fan and capacitor.

it will ice up with just one controller unless your using a huge ac unit to cool a tiny chamber... you need a second controller to control the heater that the ac units temp probe sees to prevent icing up. a coolbot is essentually that, two controllers.. one controlling a heater using evap coil temps as reference and the other monitoring chamber temp controlling normal on off control.

 

[augiedoggy]

the output of a cars ac unit is totally different since it uses flaps and fan motor speeds to control either flow or the amount of warm ambient air introduced into the air coming from the vents to make the air blow colder or warmer.

 

[Scrumpy!]

Good discussion that is perfect timing for me. I really appreciate Bobby's explanation of the closed air cycle on the evaporator side of the AC. Augiedoggy clarified the 20 deg drop in increments to round it out.

I have just built a 20 cu ft box under my work table. I have a GE 5K BTU AC ported into one end. I moved the AC's sensor from the evaporator fins to the outside of the box and wired up a cheap enclosure heater to keep it warm. I put a small ceramic heater in the box for fermenting at a controlled temp during winter months when my work-space gets cold. I have an average R of around 15 if I can believe the specs written on the styrofoam and foil insulation I used. I would have liked to get to R 25 as advised by CoolBot but did not have room. My lowest target temp is 35 deg so I can cold crash kegs or carboys. I hoped to control it all with a single ITC-1000.

On my first test run, I found that my AC was cycling every 3 min so I set the compressor delay for 5 min to allow the pressure to equalize before starting a new cycle. This configuration is not working well so far. I am icing when trying to get to temperatures below 50 deg so I will add a second ITC 1000 to plug into the evaporator fins to turn the unit off if it starts to ice. I see that some systems just shut the compressor down and let the fan melt the ice. That system would also have to have compressor delay built in.

The bigger issue is the short cycle time. I can't find any information on where to put the primary temp sensor. I mounted it about 4 ft away from the AC. The AC temporarily cools the air to any target temp in about 70 seconds before it can have much effect on the liquid filled carboys and kegs. The current configuration will take a long time to chill 25 gallons of liquid and take a toll on the AC.

I want to damp that sensor's response so the AC runs longer. Should I shield it with a short length of open ended PVC pipe? Should I move it to be directly below the AC? Should I put it in a small water bath so it responds more like my carboys? Any other ideas would be appreciated.

 

[Dland]

Your idea of a water(or antifreeze) bath for probe might work. My unit is a glycol chiller, not air box, so obviously different story, but the temp probe in glycol does not short cycle.

If you set the controller with a lower target temp with a higher trigger temp differential, you will also get longer runs. The liquid in carboys won't swing that fast, even if air temp has variation of 6-8 degrees.

 

[bracconiere]

i'll admit i just read the first post. but i don't get the lamp on the temp probe. i modded my oven a while back with a 200ohm resistor in series on the temp probe to get it to go lower...

i'd imagine for a A/C you could do something similar, and use the actual temp setting accordingly....

 

[augiedoggy]

i'll admit i just read the first post. but i don't get the lamp on the temp probe. i modded my oven a while back with a 200ohm resistor in series on the temp probe to get it to go lower...

i'd imagine for a A/C you could do something similar, and use the actual temp setting accordingly....

you need to have a heat source you can turn on and off to override the ac units built in control. and you need a secondary temp control to prevent the icing up of the unit. this is exactly how a coolbot works with a little heater instead of a bulb though.

 

[bracconiere]

you need to have a heat source you can turn on and off to override the ac units built in control

but temp probes just work on a set resistance... if you increase resistance, then it will go lower? that's what i did with my oven, stock it only goes down to 170-200f, now with the 200ohm resistor i can get it down to 90f....just using the stock temp knob....

 

[Scrumpy!]

Thanks for the suggestion. I'll try glycol. No bugs should grow in it and it will not evaporate as fast as water or alcohol.

Your idea of a water(or antifreeze) bath for probe might work. My unit is a glycol chiller, not air box, so obviously different story, but the temp probe in glycol does not short cycle.

If you set the controller with a lower target temp with a higher trigger temp differential, you will also get longer runs. The liquid in carboys won't swing that fast, even if air temp has variation of 6-8 degrees.

 

[Bobby_M]

Good discussion that is perfect timing for me. I really appreciate Bobby's explanation of the closed air cycle on the evaporator side of the AC. Augiedoggy clarified the 20 deg drop in increments to round it out.

I have just built a 20 cu ft box under my work table. I have a GE 5K BTU AC ported into one end. I moved the AC's sensor from the evaporator fins to the outside of the box and wired up a cheap enclosure heater to keep it warm. I put a small ceramic heater in the box for fermenting at a controlled temp during winter months when my work-space gets cold. I have an average R of around 15 if I can believe the specs written on the styrofoam and foil insulation I used. I would have liked to get to R 25 as advised by CoolBot but did not have room. My lowest target temp is 35 deg so I can cold crash kegs or carboys. I hoped to control it all with a single ITC-1000.

On my first test run, I found that my AC was cycling every 3 min so I set the compressor delay for 5 min to allow the pressure to equalize before starting a new cycle. This configuration is not working well so far. I am icing when trying to get to temperatures below 50 deg so I will add a second ITC 1000 to plug into the evaporator fins to turn the unit off if it starts to ice. I see that some systems just shut the compressor down and let the fan melt the ice. That system would also have to have compressor delay built in.

The bigger issue is the short cycle time. I can't find any information on where to put the primary temp sensor. I mounted it about 4 ft away from the AC. The AC temporarily cools the air to any target temp in about 70 seconds before it can have much effect on the liquid filled carboys and kegs. The current configuration will take a long time to chill 25 gallons of liquid and take a toll on the AC.

I want to damp that sensor's response so the AC runs longer. Should I shield it with a short length of open ended PVC pipe? Should I move it to be directly below the AC? Should I put it in a small water bath so it responds more like my carboys? Any other ideas would be appreciated.

You are getting short cycling because the space is so small and the cooling system is oversized. You can mitigate freezing by forcing the fan to run constantly. The best way would be to find the compressor activation wire and running that off the external controller. Where do you have the probe now? Attach it to your fermenter on the side oppposite the AC and put some insulation over it, like a 4"square.

 

[Scrumpy!]

Thanks Bobby,

I moved the sensor so it does not lie in the direct path of the air blast. I also put it in a one pint milk bottle full of water which reduced the fluctuation over each cycle to less than half a degree. I also added another inkbird in series to monitor the evaporator fins, set it at 33 with a 1 degree offset and put in a 7 min compressor delay.

These changes have extended the cycle to 11 min with the AC running for just over two minutes each cycle. The evaporator fins briefly get down to 31.5 deg after the AC shuts down at 33 deg. This has prevented icing so far. With the target temp set to 35 deg, I am down to 41.5 deg with two full corny kegs inside. The external temp is 68 deg.

I wondered if the AC was too big but 5 K BTU is about as small as I could find. If it is not reaching my target overnight I thought I would leave the fan on high but move the dial from high cooling to the midpoint between that and low cooling to see what happens. Will that reduce the load on the compressor and will it compensate for my over capacity?

 

[Bobby_M]

The low/high cooling is just fan speed. It doesnt change the compressor in any way. The fan running will help a lot. Most icing occurs when the coil is still ice cold and airflow stops. Condensation builds and freezes. If it doesn't fully thaw AND evaporate by the next cycle, you get a runaway freeze up.

Thanks Bobby,

I moved the sensor so it does not lie in the direct path of the air blast. I also put it in a one pint milk bottle full of water which reduced the fluctuation over each cycle to less than half a degree. I also added another inkbird in series to monitor the evaporator fins, set it at 33 with a 1 degree offset and put in a 7 min compressor delay.

These changes have extended the cycle to 11 min with the AC running for just over two minutes each cycle. The evaporator fins briefly get down to 31.5 deg after the AC shuts down at 33 deg. This has prevented icing so far. With the target temp set to 35 deg, I am down to 41.5 deg with two full corny kegs inside. The external temp is 68 deg.

I wondered if the AC was too big but 5 K BTU is about as small as I could find. If it is not reaching my target overnight I thought I would leave the fan on high but move the dial from high cooling to the midpoint between that and low cooling to see what happens. Will that reduce the load on the compressor and will it compensate for my over capacity?

 

[Scrumpy!]

I will have a better take on this in the morning.

My AC has two controls, one that controls fan speed and one that I interpret as a crude control of room temperature ("high cool" and "low cool") without the benefit of a thermostat that is giving the unit information about the temperature in the room. The only way for the second one to work that makes sense to me is by feedback from the fin temperature since it is the only sensor on the unit. I am working under the assumption that this second control knob tells the unit how much heat to transfer per unit of time. That would mean that it knows how cold the evaporator fins are (via the sensor clipped to them) and at "low cool" it reduces the pressure differential between the evaporator and the condenser.

Wow, that is a lot of supposition on my part since I don't know sh*t about HVAC. I await an avalanche of laughter at my ignorance and hope to learn more from my experiment and the guidance of those who actually know how this stuff works.

 

[gnef]

I went with a more 'manual' method for cooling my walk-in chambers, roughly 6 ft x 6 ft x 6ft interior space each, insulated in all directions.

All I did was modify the AC control so that when it had power, it was on full blast. I separately control the power to the AC unit with a Love digital temperature controller. My cold side is set to 40F and my warmer fermenting side is set to 60-65F typically, but that can change depending on what I'm fermenting or the charcuterie that I'm working on.

It did take some tweaking to get a good balance for chilling and not freezing up on the colder side, but you can set the short cycling time in the controller itself as well as the differential.

The only thing that you have to be careful of with this method is the fan turns off when the set temperature is reached. To mitigate this problem, I have separate computer fans attached to the front that run constantly over the evaporator coils. This is only necessary for me on the cold side.

When I replace the units, or in a major freeze up, I have to lower the temperature on the cold side gradually, otherwise it will freeze up. I now also keep a lacrosse wireless thermometer in each chamber with alarm set points so that I get warnings if the temperature is too high.

 

[augiedoggy]

but temp probes just work on a set resistance... if you increase resistance, then it will go lower? that's what i did with my oven, stock it only goes down to 170-200f, now with the 200ohm resistor i can get it down to 90f....just using the stock temp knob....

your situation is different because your using such a large btu compressor for such a small hopefully insulated space but normally...

Air conditions only cool to an offset of 10-20 degree per pass they dont really cool more or less depending on temp, they just run less or longer till the air in the room reaches temp but once that air is cold enough the unit wil; start to ice up...

permanently cheating the temp probe by making it read warmer than it really is will do nothing to prevent the icing up that will occur in most cases. thats why a coolbot contains 2 temp controllers and a tiny heater that wraps against the ac units original temp probe , to turn the ac units cooling on and off after sensing coil temp to prevent icing, much like a freezer or fridge does. it does this to put the ac coils in "defrost" mode.

 

[augiedoggy]

I will have a better take on this in the morning.

My AC has two controls, one that controls fan speed and one that I interpret as a crude control of room temperature ("high cool" and "low cool") without the benefit of a thermostat that is giving the unit information about the temperature in the room. The only way for the second one to work that makes sense to me is by feedback from the fin temperature since it is the only sensor on the unit. I am working under the assumption that this second control knob tells the unit how much heat to transfer per unit of time. That would mean that it knows how cold the evaporator fins are (via the sensor clipped to them) and at "low cool" it reduces the pressure differential between the evaporator and the condenser.

Wow, that is a lot of supposition on my part since I don't know sh*t about HVAC. I await an avalanche of laughter at my ignorance and hope to learn more from my experiment and the guidance of those who actually know how this stuff works.

high cool and low cool is just fan speed as Bobby mentioned, ac units do not run at variable power (cooling) levels there should be a cooler/warmer knob if this is an old fashioned analog ac unit and this is the thermostat control which usually allows the ac unit to cool down to 60 degrees unless modified. these old analog ac units are no good to use withe digital controllers according to coolbot.. I cant remember for sure why.. I think it has something to do with short cycling and burning them out.

 

[Scrumpy!]

I reached out to CoolBot about the use of analog AC units and here is their reply:

Unfortunately, there is no workaround for analog A/Cs. The heater cable of the Coolbot cannot work with the thermostat lead that is typical of analog systems and because of this that is the most important requisite about the A/C (digital controls-thermistor type driven).

I then asked for more details and got this:

The A/C will work, it will most likely just not go past the A/C set point or if it does, it will be very erratic and never follow the CoolBot.

Some brands like GE have smaller 5K A/Cs that are digital and should be good to use with the CoolBot for a small space.

20 cuft is definitely a very small volume so any A/C is over sized for that application, and to be honest an A/C installed in such a small space may not even work correctly (or efficiently) due to air flow restrictions or the possibility of icing up due to the excessive extra BTUS. We have had customers install small 5K A/Cs in double door refrigerators which are about 45-50 cuft, but not really on something this small.

Over capacity/short cycling seems to be the real issue. By running two InkBirds in series, I have the icing problem resolved. The InkBirds seem to control the unit without any "erratic" behavior. Any thoughts on how to reduce the output or efficiency of an analog AC?

 

[RickyS]

hi all. I am trying to wire my inkbird itc-1000 to a portable arctic King AC unit with 8000 btu. My cool storage room is 4’x8’x6’ tall. I’ve tried a variety of wiring configurations but can’t seem to get the inkbird to get the unit to start cooling. Attached is the wiring diagram for the portable ac unit and the inkbird. I tried splicing into the red wire going to the compressor and the blue one between condenser and compressor with the inkbird wiring diagram, but neither configuration worked. I then wired the inkibird running the blue wire with the hot wire from port 1 then through pole 7 and 8 using it as a switch. When I powered it up I could hear the compressor start and then I powered the ac unit, but it still wouldn’t cool. What am I doing wrong? By the way, I am new to forum’s and not that tech Davy so forgive me if I should be on another thread

 

[Bobby_M]

First, don't connect any of the connections as shown here:

The blue wire going to the compressor gets cut and each cut end goes on terminal 7 and 8. Basically the ITC-1000 just reconnects the blue wire for you when it needs to cool.

Now here's where it gets interesting. This arrangement will only cool as cold as the built in thermostat for the portable AC. If that's low enough great.

If it's not, you'll need to use a reverse approach. You would need to put a small low wattage heat source on the AC's built in temp sensor and that heat source would have to be switched by the 7/8 terminal instead. That way when the ITC calls for cooling, it actually heats up the sensor on the AC. Doing it this way will let you run the AC well below it's built in thermostat.

Acceptable heat sources would be a small 1 watt light bulb, a very small cartridge heater, A 2 watt resistor rated at 10,000 ohms...

 

[RickyS]

First, don't connect any of the connections as shown here:

View attachment 741714

The blue wire going to the compressor gets cut and each cut end goes on terminal 7 and 8. Basically the ITC-1000 just reconnects the blue wire for you when it needs to cool.
View attachment 741715


Now here's where it gets interesting. This arrangement will only cool as cold as the built in thermostat for the portable AC. If that's low enough great.

If it's not, you'll need to use a reverse approach. You would need to put a small low wattage heat source on the AC's built in temp sensor and that heat source would have to be switched by the 7/8 terminal instead. That way when the ITC calls for cooling, it actually heats up the sensor on the AC. Doing it this way will let you run the AC well below it's built in thermostat.

Acceptable heat sources would be a small 1 watt light bulb, a very small cartridge heater, A 2 watt resistor rated at 10,000 ohms...

this is great.Very helpful. Thank you.I’m in Canada so think in Celsius. My AC unit only goes down to 17 degrees. I want the unit to cool somewhere between 2-5 degrees.

thanks again.

 

[LarMoeCur]

I wondered if the AC was too big but 5 K BTU is about as small as I could find. If it is not reaching my target overnight I thought I would leave the fan on high but move the dial from high cooling to the midpoint between that and low cooling to see what happens. Will that reduce the load on the compressor and will it compensate for my over capacity?

I have a 5k BTU unit running in a 4x3x3 box with 1.5" foam insulation. Wrapped with 1/4 particle board, making the internal closer to 3.66'x2.66'x2.66'. So, my dimensions are even smaller than yours. I'm controlling mine with an Inkbird ITC-308. I lager at 42 all the time. I've never had my unit freeze up.

Did you seal the unit into the chamber? To me it sounds like it's running to long not short cycling. Your box may not be insulated enough or you have your cold air leaking out some where.

Are you trying to take the beer from the 60s into the 40s in one cycle of the a/c unit? I've always dropped mine is 5 degrees increments to not over work the a/c unit.