air conditioner not working.

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  #1  
Old 06-29-15, 09:20 PM
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air conditioner not working.

I have a comfortmaker air conditioner, and comfortmaker heatpump/furnace. I recently had to move my ac about 20 ft. I had a technician come out and assist in the move. He ran new cooling lines, and we junction boxed the 240V wire. We also had to extend the 24 V wires to the air conditioning unit. After the move, the lines were re-charged and everything worked about a week.

Now the issues. ( I am new to this but have been researching.)
I noticed the fan running and blowing air through the duct work but not cold. I seen that the air conditioning was not running. (no condensor and no fan on ac). I checked and seen that I had 240 Volts incoming so no fuses/breakers were my issue.. I checked the contacter 24V terminals, and had no voltage.

I pushed the contact in and the unit turned on. Upon further review, it looked a little corroded, so I then replaced the contactor. This didn't fix the problem.

So, i started with the thermostat. When reading with a multimeter on the board from red to yellow wires inside the furnace/heat pump that is labeled thermostat, I read 28V with thermostat set to off and auto for the fan. I then changed the thermostat to Cool and auto. As soon as i did that, the multimeter went to 0V on the same board. So, i think my thermostat is sending the correct Voltage change to the board on the heatpump inside furnace.

Where i get confused next is, when i check the red and yellow wires at the junction, i am reading 28 Volts with the thermostat off. When i turn the thermostat on to Cool, I continue to read 28 Volts. My assumption is that is my problem: Shouldn't that drop to 0 Volts like it did on the board?

Thanks in advance. I am appreciate of any help. I am new to the HVAC system. Is there any other tests that I should do at this point? Is there anything that i should jumper on the air conditioning unit to see if it turns on without me pushing the contactor in?

Thanks
Mitch
 
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  #2  
Old 06-30-15, 04:36 AM
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Yes, you should read 0V between the R & Y wires both at the thermostat and at the furnace control board. It appears that you may have either a disconnected or broken wire (most likely the Y wire) somewhere between the thermostat & furnace. Was any work done on/with the thermostat when the tech moved the outside A/C unit? If so, my guess would be that the Y wire broke inside the insulation, near where it connects to the thermostat. To check that, disconnect the Y wire from the thermostat and give the copper wire a gentle tug with a pair of needle nose pliers. If the end of the wire doesn't pull out of the insulation, it's not broken near the thermostat end. You would need a multimeter to go further with the testing.

One check you could do is to jumper the R & Y terminals at the furnace control board and see if the outside unit turns on. If it does, it means that the outside unit and the wiring to it is good. The problem is between the thermostat and the control board.
 
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Old 06-30-15, 05:15 AM
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It would appear that the problem is the cable between the condenser and air handler,as stated jump R&Y at the control board and see if the condenser runs,if that cable was lengthened I would check the splice point.
Geo
 
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Old 06-30-15, 08:16 AM
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I am a little confused....

-Just to start.....nothing was moved or touched at thermostat, or the furnace when the technician was here...

(Looking at the attached picture....the terminals on the bottom that are marked thermostat.)
1) Thermostat set to off= red and yellow is reading 28V
2) I turn the thermostat to Cool/Auto Fan.
I am now reading 0 volts between red and yellow at the control board where it says thermostat.

This is correct, right?

This should mean that my thermostat to my board on my heat pump/furnace is working fine, correct?

(Looking at the attached picture....the terminals on the top that says outdoor)
1) I always see 28V between red and yellow whether the thermostat is set to off or the thermostat set to Cool.

My assumption is when the thermostat sends a signal to the board through thermostat connections, I should also see Outdoor terminals red and yellow drop to 0 Volts, is that correct?

(I checked the red and yellow wire at the junction (with thermostat set to off and cool), and I am already reading 28V.) Should this go to 0 V when the thermostat sends signal to furnace board, then sending 0V signal through this wire that we junctioned to AC board?

If I jumper the red and yellow wire at the furnace control board, what will that do?....
 
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Old 06-30-15, 08:35 AM
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I don't see any picture, however you are correct in that when the thermostat is calling for cooling there should be 0 volts between R and Y both at the thermostat and the control board. If you measure AC voltage from chassis ground (chassis of furnace) to R and Y, you should always read 24VAC (28 in your case) from R to ground, and 24VAC from Y to ground when calling for cooling. Can you find where the wire going outside connects to the furnace? You should measure 24/28 VAC across the two wires when the thermostat is calling for cooling. If you do, however you don't have voltage at the outside unit, it would indicate a break in the wiring going outside.

The reason why we suggested trying to jumper R & Y at the control board was because we understood you to say (earlier) that you were measuring 28VAC between R & Y at the control board, but 0V at the thermostat.
 
  #6  
Old 06-30-15, 10:25 AM
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[IMG]http://i60.************/29vdor4.jpg[/IMG]

2nd attempt at adding picture.

I believe that the wiring that connects the air conditioner to the furnace are on the same board in the furnace....(I think) If you can see the picture, please confirm.

When I am checking the splice between the red and yellow wires from the furnace to the air conditioner, I see 28 volts whether I am calling for cooling or not. Should checking R and Y at this point drop to 0V when cooling is called for?

I need to check the wiring on the ac unit after work tonight. It was raining last night, so I couldn't check anything outside.
 
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Old 06-30-15, 10:28 AM
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one more attempt at adding the picture


[ATTACH=CONFIG]52666[/ATTACH]
 
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  #8  
Old 06-30-15, 10:59 AM
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OK, your picture now shows up, however it's so small it's very difficult to tell much, other than I see that the thermostat wires are on the bottom. It appears (again, hard to tell for sure) that the wires to the outside unit are connected to the terminals on the top of the board. Do you know which ones are the pair that go to the outside unit? If so, you should read 24/28 VAC across them when the thermostat is calling for cooling. It doesn't matter what color the wires are, just read the AC voltage across the pair of wires going outside (the low voltage or control wires, not the 240VAC). Let us know if you measure voltage across the terminals going outside when calling for cooling.
 
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Old 06-30-15, 03:13 PM
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Am I correct to assume that "R" and "Y" is the main power and the air condition wire....

The thermostat is off. I check the "outdoor" terminals on the board at the furnace that are labeled D,T,T,R,B,O,Y. I check between the R and Y,and I am reading 28 volts. These are the wires that go to the air conditioner.

Is there something wrong, because i believe after reading the last post, that this should be reading 0 volts going out from the furnace when there is no call for AC?

I then turned the thermostat on to Cool and I still continue to read 28 volts going between the R and Y wires. It appears nothing changes.
 
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Old 06-30-15, 03:23 PM
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My guess is that you're not looking at the correct wires. The 24/28VAC should only be present on the wires going to the outside unit when the thermostat calls for cooling. If the 24VAC was present all the time, the outside unit would run continuously, never shutting off. You may have to have someone go outside and gently pull on the wires going to the outside unit where they come out of the house, while you watch to see what wires (in the basement) are moving. Or, if you have a wiring diagram for your furnace, you could see what terminals the outside unit should be connected to.
 
  #11  
Old 06-30-15, 04:44 PM
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I am 100% sure that I am looking at the correct wires. I helped splice the wires. This is why I am so confused.

When the thermostat is off, I am reading 28V between R and Y on the furnace board that reads thermostat. I immediately put the multimeter on the R and Y that is on the same board that is labeled outdoor. I am also reading 28V, which I believe you are telling me shouldn't be happening.

When the thermostat is on, I am reading 0V between R and Y on the furnace board that reads thermostat. I immediately put the multimeter on the R and Y that is on the same board that is labeled outdoor. I am STILL reading 28V.

I go to the air conditioner board. I turn the thermostat to off. I put the multimeter on the R and Y terminals. I am reading 28.4V. I kept the multimeter on the R and Y and had the wife change to cool. The voltage essentially stayed the same. (it went to 25.6V)

If the thermostat is "off" should there be any voltage coming into the ac?
 
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Old 06-30-15, 04:56 PM
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If I understand you correctly, there is always ~24VAC on the control (low voltage) line coming into the outside unit, regardless of the thermostat setting. This is not correct, however it should give you the opposite of what you're experiencing. The outside unit should be running continuously regardless of the thermostat setting. However, I understand you to say that the outside unit is not coming on at all unless you manually press the contactor. Have you tried measuring the voltage between the side terminals on the contactor? That should correspond to the low voltage (24VAC) voltage coming from the house/furnace/thermostat. If you have 24VAC coming into the outside unit but no 24V at the contactor, then something is preventing the control voltage from getting to the contactor. Often there will be high or low pressure switches or a timer circuit in series with the control voltage (between where it comes into the outside unit and the contactor). Your wiring diagram should show if any of these switches are present on your outside unit.
 
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Old 06-30-15, 06:48 PM
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Yes, i am seeing 24V coming into the defrost card at all times.

There were some corroded areas and some "burnt" spots on the defrost board, so I replaced the board with the same wiring configuration that was on there. I am not sure if the technician had ever changed anything or not prior to me changing the board out. Does not work yet.

On the contactor sides, how am i suppose to check the voltage? I put the multimeter to each side of the connector and I am reading 0V. I follow the 2 blue wires back to the defrost board which is connected to the "CC" or compressor contactor according to the new instructions.

I am looking at the wiring compared to what the defrost board came with for a wiring diagram and it doesn't appear that it is wired the "exact same." It appears that on the wiring diagram there is a wire that should be going into Y/RV and connects into RV. The way the wiring is on my unit, the Y/RV is not being used, and there is a wire plugged into the R/RV. I don't have any time to trace where all the wires go to, but I can tomorrow night.

I don't see any other switches. There is a jumper wire that goes from PS1 to PS2.
 
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Old 06-30-15, 07:07 PM
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Hope these pictures help.....

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Last edited by PJmax; 07-02-15 at 04:32 PM. Reason: reoriented/enlarged pic
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Old 06-30-15, 07:11 PM
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Hope these pictures help
 
  #16  
Old 06-30-15, 07:17 PM
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The wiring diagram is hard to read in many areas on the air conditioning cover. Too many years sitting outside
 
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Old 07-01-15, 07:31 AM
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From the pictures/diagrams you posted, it appears (to me) that you may have a wiring error. I'm not an expert on these things, just an educated homeowner and electrical engineer. The reversing valve is what determines whether the heat pump is running in heating or cooling mode. From the picture of the wiring diagram, it appears that it should be connected between Y/RV & RV. Since you don't have any wire on Y/RV, I'm not sure what, if anything, the reversing valve is connected to. Since you have a jumper between PS1 & PS2, it appears that you don't have any high or low pressure switches.

Have you checked the voltage at the Y terminal on the board pictured? This appears to be the terminal that is connected to the Y terminal from the furnace/thermostat. If you read the AC voltage between terminals Y & C (C is common/ground), you should read 24VAC when the thermostat is calling for cooling and 0V otherwise. It also appears that the 24VAC should also appear across the CC terminals (two blue or purple wires with red terminals) when the thermostat calls for cooling. Measure the voltages from Y to C and between the two CC terminals and let us know what they are (thermostat OFF and calling for cooling).
 
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Old 07-02-15, 02:13 PM
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I re-checked the wiring....

I have 28V at all times on the R wire. (off or cooling)

I checked the Y to C wires and read 0V when unit is off
I checked the Y to C wires and read 0V when the unit is on Cool.

I checked across the CC terminals and get 0V when unit is off
I checked across the CC terminals and get 0V when the unit is on Cool.

Is there anything that i can/should jump to give voltage to a terminal that will turn the ac unit on without me pushing in the contactor?

It appears that i have 2 different problems.... 1)I shouldn't always have 28V on the R wire coming from the furnace, when the thermostat is off, correct? 2) the ac unit should always be on and right now is doesn't ever turn on .

When the voltage comes in on the R wire (which i always have), what is the next thing that should happen? Should the CC wires become 28V which turns the contactor on? IF so, what can cause the CC wire to not become charged to 28V?
 
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Old 07-02-15, 02:32 PM
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First off, R is the output of the 24V transformer and should always have voltage referenced to the C (ground) terminal, so that is okay (no problem). The Y wire is the one coming from the house. This is the one that got lengthened and is likely the source of the problem. Earlier, you said that you had 28VAC at the Y wire inside the house before it went outside. If that is still the case, then you have a break in the control signal wires (Y & C) somewhere between the house and the outside unit. You might want to double check that you have 24/28 VAC (referenced to C or ground) inside the house (furnace) at the wire that goes to the Y terminal outside.

When the thermostat calls for cooling, a relay inside the thermostat closes, connecting the R to the Y wires, sending 24VAC to the Y terminal on the furnace board. The furnace board should, in turn, send the 24VAC to the control line going out to the outside unit (Y terminal on board). The 24VAC then gets sent to the contactor causing it to energize, pulling the contacts down and turning the outside unit on.
 
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Old 07-02-15, 07:41 PM
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Ok, I misunderstood you earlier.

When i connect the Y to B on the furnace board, i have 0 Volts when the furnace is off.

When i connect the Y to B on the furnace board, i have 0 Volts when the furnace is set to Cool. Nothing is happening at this point. If this is the case, is the relay bad to get this to turn on? If I make a jumper wire and connect the R to the Y, that should send 24 v to the ac unit and turn it on correct?

If i should do this, i can and that will be my next test.

Thanks
Mitch
 
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Old 07-03-15, 05:11 AM
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This is the first time you've mentioned the B terminal. B is normally used with heat pumps and controls the operation of the reversing valve. All of your voltage measurements should be made relative to the C (Common or ground) terminal. Assuming that you meant C instead of B, I understand you to say that you have 0 volts at the Y terminal on the furnace board when calling for cooling. As I recall from the picture you put up earlier, there are two sets of terminals on your furnace board, one marked "Thermostat", and the other (I think, hard to read) says "Outdoor". Assuming this is correct, which Y terminal are you referring to that has 0 volts when the thermostat calls for cooling?

Here's what I would suggest you try to check the integrity of the wiring going outside and the outside unit itself:

1) Find the wire that connects to the furnace board and goes to the outside unit. It may be connected to the Y terminal on the Outdoor terminal strip.

2) Remove the wire in step #1 from the furnace board. There likely will be a second wire connected to the C terminal. Leave that connected.

3) Temporarily jumper from the R terminal (24VAC) on the furnace board to the wire you disconnected in step #2. If the wiring leading outdoors is good and the outside unit is okay, it should start up and run as long as the jumper wire is in place. If the blower inside the house is running (it should be), you should start to feel cool air from the vents after a few minutes of running.

Let us know how you make out and we'll take it from there.
 
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Old 07-05-15, 08:48 AM
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On the furnace board....

(side that is labeled thermostat) Terminal letters to connect to are R,Y,G,W,O,and B. (there is no terminal that is called C or CC on this board.)
Measuring between Y and B with thermostat off, i get 0V.
Measuring between Y and B with thermostat cool, i get 28V.

(side that is labeled outdoor) Terminal letters to connect to are D,T,T,R,B,O,and Y. (there is no terminal that is called C or CC on this board.)
Measuring between Y and B with thermostat off, i get 0V.
Measuring between Y and B with thermostat cool, i get 0V.
-If I am understanding you correctly, as soon as i call for cooling, this should have changed to 28V.

The wire that is plugged into B on the furnace board is "blue in color." This is the case on both the thermostat and the outdoor side of terminals. When i follow this blue wire outside it plugs into the board on the Air conditioner on the "C" terminal. This tells me that the B terminal downstairs is the Common wire.

Assuming I am making sense in what I just wrote, I believe that you want me to unhook the "Y" wire that is plugged into the furnace board on the "Outdoor" side. Then i need to make a jumper wire that connects the R terminal and the Y terminal. At this point, it should send 28V outside through the Y wire. Then, i can make sure that outside i am reading 28V between "C" and "Y".

Does this make sense?

Thanks
Mitch

By the way, I appreciate all the time and help that others on this board are providing! Thanks again.
 
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Old 07-05-15, 09:26 AM
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Mitch, thanks for the detailed explanation. You are correct in that it appears that the Blue wire on the B terminal is the Common (ground). Assuming that the Y terminal on the Outside connector is the other (control signal) wire going out to the outside unit, you should remove the Y wire from the Outside terminal strip and jumper it to the R terminal. This should give you 24/28VAC between Y & C at the outside unit (if the wiring outside is good). With any luck, the outside unit should turn on and you should get cooling.
 
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Old 07-05-15, 06:39 PM
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Well, finally we are getting somewhere....

I unplugged the Y wire on the "outdoor" side of the furnace board. I plugged it into the "R" to give it 28V. I went outside to check if anything was running but it wasn't. I measured the voltage at the ac between the "C" and the "Y" and I am getting 28V. Then all of a sudden the air conditioner turned on.... There must be a 3 minute delay, because when i was checking everything over, it suddenly turned on. I turned the breaker off for the 24V system, and reset the breaker to on. I timed the length of delay, and it took 3 minutes and the AC turned back on the second time.

So, I believe there is an issue with getting the 24 V to the outside from the board on the furnace. Does this mean that the "relay" is bad? If so, do i need to get a new board to fix this problem? Is there anyway to fix just a relay or does the entire board get replaced?

Is there anything else that I need to do or try at this point?

Thanks!
 
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Old 07-06-15, 05:02 AM
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Mitch, glad to hear you're making progress. I've been suspicious of the furnace board. Since you have 28VAC between Y & B at the Thermostat terminals, but 0V between Y & B at the Outdoor terminals, it would indicate a problem with the board. It's very possible it's something as simple as a relay, however unless you can diagnose the bad component and find a suitable replacement, you might end up just replacing the board. Unfortunately, you're unlikely to find any component level service information for the board. Manufacturers generally treat the board as a "black box", just showing what's connected to it, not what circuitry is on the board itself.
 
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Old 07-06-15, 07:32 AM
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This may be a really dumb idea, but had a thought/question.

When the thermostat is off, and I am measuring Voltage between Y and B on the "Thermostat" side of the furnace board I get 0V.

As soon as I call for cooling by the thermostat, I now get 28V in the Y wire at the thermostat terminals.

Here is my question:
What would happen if I run a jumper wire from "Y" on the Thermostat side to the "Y" at the "Outdoor" side. I believe that as soon as I call for cooling from the thermostat, I would energize both the "thermostat" and "outdoor" "Y" terminals. I believe that I would just permantly by-pass that relay....

Is this a bad idea???? (It may be... please advise.)

Thanks
Mitch
 
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Old 07-06-15, 07:57 AM
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That may or may not work. In theory, it should work. In practice, it depends upon how much of a load the circuitry on the board presents. If it presents too much of a load, the transformer fuse (if you have one) may blow. Perhaps a better idea would be to remove the wire going to the outdoor unit from the Y terminal on the outdoor terminal strip and connect it to the Y terminal on the Thermostat terminal strip. Alternatively, you could remove both Y wires from the Thermostat & Outdoor terminal strips and merely connect the two wires together. This would bypass the furnace board entirely. I would suggest that you try this scheme (both wires removed) first. If it works okay, you could just leave it this way.
 
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Old 07-10-15, 05:57 PM
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Thank you for all the help!!!!

I ordered a new board for my furnace. I replaced the board and now the ac turns on. The problem was that the relay on the furnace board went bad and no longer turned on when the thermostat called for "Cool"!!!!

Thanks again for all the insight. I couldn't have done it without this site!
 
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Old 07-10-15, 06:24 PM
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Mitch, glad to hear that you got the system working again. Your persistence paid off.
 
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Old 07-10-15, 10:43 PM
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So thankful I came across this...may have solved my problem too!
 
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