Original message
| john469b
 |  "Lennox t89b3861 to honeywell rth7500"
, posted Tue 13 May 07:04:  
Trying to install new thermostat. Old lennox wired as followed
o-orange
g-green
y1-yellow
r-red
L-blue
C-black
W1- white
t-tan
I wired new one as followed and house will not cool.....fan works but no compressor
rc-jumper to red
r-red
o/b-orange
y-yellow
g-green
c-black
L-blue
e-nothing
aux-white
left tan off
Someone please tell me what I did wrong
170 set to 7
190 set to o
[this message was edited by john469b on Tue 13 May 16:52] |
| Replies:
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| Houston204
| "Re(1):Lennox t89b3861 to honeywell rth7500" , posted Tue 13 May 08:25:
Can you turn off the fan from your stat?
If you forgot to remove power to your air handler before replacing your stat, you may have tripped a low voltage breaker or fuse in your air handler.
Removing power to the outdoor unit doesn't work.
"Tip of the Day" Remember to remove power first.
[this message was edited by Houston204 on Tue 13 May 08:27] |
| | john469b
| "Re(2):Lennox t89b3861 to honeywell rth7500" , posted Tue 13 May 08:49
yes, I turned the breakers off to the unit and I can control the fan with the t-stat. But no cool air. Is it wired correctly?
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| | john469b
| "Re(3):Lennox t89b3861 to honeywell rth7500" , posted Tue 13 May 09:10:
I think it is a k674801 or K67 4811 thermostat. Please help!!!!
[this message was edited by john469b on Tue 13 May 16:56] |
| | Houston204
| "Re(4):Lennox t89b3861 to honeywell rth7500" , posted Tue 13 May 19:25:
You need a jumper between Aux and E, but otherwise it is wired and configured correctly.
Do you have 240 volts to your outdoor unit?
Do you get 24 volts between C & R, C & Y, and C & O when you give your thermostat a cooling demand?
You can bypass your stat by twisting red (power), orange (reversing valve) and yellow (compressr) together at your stat.
I have seen some units run the fan continously when the low voltage fuse in the heater pops.
Since you can turn the fan off and on from your stat, it eliminates that possibility.
"Tip of the Day" Remember to remove power first.
[this message was edited by Houston204 on Tue 13 May 19:30] |
| | john469b
| "Re(5):Lennox t89b3861 to honeywell rth7500" , posted Tue 13 May 21:01:
I have had it going for about 2 hours without the jumper between aux and e. The compressor seems to be running but it is about 78 to 80 degrees outside and it will only cool to 78. Will this jumper make any difference in that. Everthing was fine until I got the bright idea to install a new t-stat. I will get my meter and check voltage at the recommended locations and post results. Thanks for the help. I went out and check voltage and I do have 24 volts across all recommended checks.
[this message was edited by john469b on Tue 13 May 21:18] |
| | Houston204
| "Re(6):Lennox t89b3861 to honeywell rth7500" , posted Tue 13 May 23:21:
Aux is stage 2 heat, E is emergency heat. They both control your electric heat strip and will not improve cooling performance.
Is the large insulated copper pipe between the house and your heat pump cold?
Disregard the control wire comment...
Your compressor is probably locked out on thermal protection. This can occur when a unit is short cycled.
If this is the case, you can cool it down with a water hose. Rinsing the condenser coil wouldn't hurt. (Unless you forget to remove power)
"Tip of the Day" Remember to remove power first.
[this message was edited by Houston204 on Tue 13 May 23:23] |
| | john469b
| "Re(7):Lennox t89b3861 to honeywell rth7500" , posted Wed 14 May 00:06
The copper pipe is cool but not cold. I check it with new and old t-stat....about the same. I did verifiy that the new t-stat was activating the copmressor contact. It will just not blow cool air. If i leave the unit off all day and retry tommorrow should the lockout be over. I have reinstalled my old one so I can sleep tonight.......it works great. It is reading about 75 degrees and the new one is sitting right on top and reads 78?????
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| | Houston204
| "Re(8):Lennox t89b3861 to honeywell rth7500" , posted Wed 14 May 08:10
I wonder if the old mercury bulb or the new digital thermostat is more accurate.
Sounds like your refrigerant charge is low. The large copper pipe should be cold. (@ 55 degrees)
"Tip of the Day" Remember to remove power first.
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| | john469b
| "Re(9):Lennox t89b3861 to honeywell rth7500" , posted Wed 14 May 08:20
I am going to install the new one again today and see what it does then call a tech to check the unit out and see if it is working properly. I used the old one last night and had it set to 70 degrees. Looked at new one sitting on top and it said 75. I bet the old one is not accurate.
With the new one it is almost like the heat strips are trying to run also.
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