Nest - Rc wire note recognized (code: e73)
#1
06-01-18, 01:33 PM
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Nest - Rc wire note recognized (code: e73)
I had the Nest for 2 years now...yesterday it saying "Rc wire note recognized"
My A/C wasn't turning on so I went outside and replaced the capacitor and install a hard starter kit. Now I'm getting a "Rc wire note recognized" on my Nest. I looked around for a fuse to see if it was popped but theres none to be found. My furnace looks old... maybe made in 1977.
Anyone have any idea what going on here?
Thanks for any advice.
My A/C wasn't turning on so I went outside and replaced the capacitor and install a hard starter kit. Now I'm getting a "Rc wire note recognized" on my Nest. I looked around for a fuse to see if it was popped but theres none to be found. My furnace looks old... maybe made in 1977.
Anyone have any idea what going on here?
Thanks for any advice.
Last edited by SoildSnake; 06-01-18 at 01:44 PM. Reason: missing image
#3
06-01-18, 04:45 PM
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You're going to need a meter to make voltage checks. Check from Y1 to Rc at the stat for 24vac. If it's not there.... check at the control area there from R to C for 24vac.
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06-01-18, 04:59 PM
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#5
06-01-18, 05:14 PM
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#6
06-01-18, 05:20 PM
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yes I'm getting 24 vac on R and C at the at the furnace wire area.. but getting not thing at the thermostat wires....i also checked outside unit everything seem good, you think its the contactor?
Last edited by SoildSnake; 06-01-18 at 05:41 PM.
#7
06-01-18, 05:43 PM
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Look at my diagram....
The red from the condenser goes to yellow of the stat.
The white from condenser goes to C.
The green from stat goes to G.
The white goes to W.
You need to follow the red wire that goes to the stat. It does not look like it goes directly to R. If it doesn't..... something is interrupting it..... possibly a float switch in the A/c pan or drain.
The yellow and red wires there with that orange wire nut should be on the Y terminal but that isn't causing this problem.
The red from the condenser goes to yellow of the stat.
The white from condenser goes to C.
The green from stat goes to G.
The white goes to W.
You need to follow the red wire that goes to the stat. It does not look like it goes directly to R. If it doesn't..... something is interrupting it..... possibly a float switch in the A/c pan or drain.
The yellow and red wires there with that orange wire nut should be on the Y terminal but that isn't causing this problem.
#8
06-01-18, 05:53 PM
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not the float switch in the A/c pan or drain...that was the 1st thing i checked. All wires are correct.
#9
06-01-18, 05:58 PM
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Look at the 4 wire thermostat cable. I identified white, yellow and green.
Where does the red wire go to in that cable ?
Not R..... correct ?
Your stat needs the R wire to work.
Just to describe the circuit.....
24vac leaves that control on R and goes to Rc on stat. When in cool mode...... 24vac is sent back down the Y1 yellow wire out to the condenser. The C wire from the condenser completes the loop.
Something in that loop is open.
Where does the red wire go to in that cable ?
Not R..... correct ?
Your stat needs the R wire to work.
Just to describe the circuit.....
24vac leaves that control on R and goes to Rc on stat. When in cool mode...... 24vac is sent back down the Y1 yellow wire out to the condenser. The C wire from the condenser completes the loop.
Something in that loop is open.
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06-01-18, 06:06 PM
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#11
06-01-18, 06:12 PM
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In every picture..... the red wire is blocked. Just visually check it. Does the red wire from that 4 wire cable go directly to R ?
#12
06-01-18, 06:21 PM
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#13
06-01-18, 06:38 PM
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Ok..... good.
If you go to the nest and take it off the base you should measure 24vac from
R to W
R to G
R to Y.
If you don't measure anything on R to Y. Leave the base off. Go to the furnace..... remove the orange wire nut from the yellow and red splice and just touch those two wires to R. If the A/C condenser doesn't start..... your problem is between there and the condenser.
If you go to the nest and take it off the base you should measure 24vac from
R to W
R to G
R to Y.
If you don't measure anything on R to Y. Leave the base off. Go to the furnace..... remove the orange wire nut from the yellow and red splice and just touch those two wires to R. If the A/C condenser doesn't start..... your problem is between there and the condenser.
#14
06-01-18, 07:15 PM
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from the base I'm not getting any thing from
R to W
R to G
R to Y.
okay I took off the orange nut from the yellow and red splice and touched those two wires to R. Nothing came on.
R to W
R to G
R to Y.
okay I took off the orange nut from the yellow and red splice and touched those two wires to R. Nothing came on.
#15
06-01-18, 09:28 PM
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We're sort of going around in circles here.
IF.... you measure 24vac from R to C at the control board.
And IF the 4 thermostat wires are connected.... there would have to be voltage at the stat.
Try a jumper from R to W at the board. That should start the furnace.
Try a jumper from R to G at the board. That should start the blower.
IF.... you measure 24vac from R to C at the control board.
And IF the 4 thermostat wires are connected.... there would have to be voltage at the stat.
Try a jumper from R to W at the board. That should start the furnace.
Try a jumper from R to G at the board. That should start the blower.
#16
06-01-18, 10:09 PM
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okay i tested again from the thermostat this is what I'm getting.
R to W 12.20 vac
R to G - 24 vac
R to Y. - 1.084 vac
Nest thermostat is still blank...no power
R to W 12.20 vac
R to G - 24 vac
R to Y. - 1.084 vac
Nest thermostat is still blank...no power
#17
06-02-18, 09:10 AM
Still pointing to Y being the problem or the connection between C at the furnace and C at your outside a/c condenser's contactor. Check the connections to the contactor. Or remote possibilty of an open contactor (measure ohms across terminals to be sure).
#18
06-02-18, 09:20 AM
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Yes... definitely.
The voltages measured at W and G are ok.
You've previously touched the yellow wire to R at the board with no response.
The two wire cable that goes out to the condenser is in question.
Also the contactor and a possible low pressure switch.
You could be low on refrigerant. That would keep the line open.
The voltages measured at W and G are ok.
You've previously touched the yellow wire to R at the board with no response.
The two wire cable that goes out to the condenser is in question.
Also the contactor and a possible low pressure switch.
You could be low on refrigerant. That would keep the line open.
#19
06-02-18, 09:56 AM
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I'm getting 24vac from Red wire from the thermostat.....would a bad compressor be the cause of the issue?
I hold down the bar from the contactor from the outside unit ...ONLY the FAN is coming on but not the compressor.
I hold down the bar from the contactor from the outside unit ...ONLY the FAN is coming on but not the compressor.
#20
06-02-18, 10:18 AM
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No.... a bad compressor won't cause the problem but the fact that the compressor and fan aren't coming on together is a problem.
#21
06-02-18, 10:30 AM
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#22
06-02-18, 11:17 AM
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You need a complete loop for the nest to work. You do NOT have a complete loop.
Your nest needs to steal power from the circuit to charge.
Look at the diagram. R is 24vac and C is technically 24vac - or ground.
Think of R as positive and C as negative. The nest needs both to charge. It gets its "positive from the R connection. It gets its "negative" thru the contactor and the lo pressure switch inside the condenser. You have something open in the outside condenser line. As long as that circuit is open.... the nest will not function.
Your nest needs to steal power from the circuit to charge.
Look at the diagram. R is 24vac and C is technically 24vac - or ground.
Think of R as positive and C as negative. The nest needs both to charge. It gets its "positive from the R connection. It gets its "negative" thru the contactor and the lo pressure switch inside the condenser. You have something open in the outside condenser line. As long as that circuit is open.... the nest will not function.
#23
06-02-18, 11:56 AM
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you're corrected there was a loose wire on the outside contactor that's why the Nest wasn't working. So that part is now fixed.
NOW back to my 1st issue with the compressor not coming on.
Note: I also installed a hard starter for the compressors.
I tested and power is coming from the compressor but its not coming on for some reason.
NOW back to my 1st issue with the compressor not coming on.
Note: I also installed a hard starter for the compressors.
I tested and power is coming from the compressor but its not coming on for some reason.
Last edited by SoildSnake; 06-02-18 at 12:24 PM.
#24
06-02-18, 12:50 PM
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I would put on a pair of safety glasses and carefully remove the cover from the compressor wiring access. That location is a weak link in the compressor and can blow out if compromised.
First look for loose burned wires. If they look ok you'll need an ohmmeter to check the compressor windings.
First look for loose burned wires. If they look ok you'll need an ohmmeter to check the compressor windings.
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06-02-18, 02:24 PM
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#26
06-02-18, 02:30 PM
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06-02-18, 02:38 PM
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#28
06-02-18, 02:49 PM
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Ok. Just so you know.... we can't help you with that in the public forums.
Only an EPA licensed tech can handle R22 products.
Only an EPA licensed tech can handle R22 products.
#29
06-02-18, 02:54 PM
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okay so i removed the cover from the compressor and this is what i found...can this be fixed?
Last edited by SoildSnake; 06-02-18 at 03:43 PM.
#30
06-02-18, 03:56 PM
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#32
06-02-18, 05:32 PM
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#33
06-02-18, 07:18 PM
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You're welcome.
Make sure all three of those connections are clean and tight so you don't have a repeat.
Make sure all three of those connections are clean and tight so you don't have a repeat.
