Thermostatic Controls - Problems with installation of Honeywell RTH7500

I have two York heat pumps that were connected with Honeywell Q674L 1272 thermostats. I wanted to change over to digital programmable ones and called Honeywell and they recommended the RTH7500 model and gave me the wiring instructions for it.

One of the issues I had with my first floor thermostat was that when the heat or AC turned on and reached its temp, the blower would never shut off. It would always blow out air. I'd have to toggle the heat/off/cool switch to finally get it to shut off. The upstairs one always seemed to work. Keep that in mind.

So I have the wiring for both this way (per Honeywell's and the manual's instructions):
W-> Aux
B -> C
G -> G
R -> R (with Rc jumpered)
X -> E
O -> O/B
Y -> Y

When I set the system to Heat and have the temp set to something higher than the ambient temp, the system comes on and blows hot air. When it either reaches the temp or I lower the temp to something lower, I hear the thermostat click and the Heat On indicator goes away but the blower is still on. Now it is blowing just air. It never goes off. I've waited about 20 minutes at times. To get it to go off, I have to switch back to Heat, raise the temp for it to click on and have Heat On. Then I manually set the system to Off and sometimes the fan shuts off. I have to do this a few times.

This is also happening with my 2nd floor unit too!

And finally I noticed that if I have it on Cool and set the temp to say 67, it gets down to 67 but stays on "Cool On" and doesn't try to shut off. I assumed once a thermostat reaches its target temp that it would shut off.

Please, any help would be appreciated. I also need to call Honeywell tomorrow :confused:

You got it wired up right.

What is your setting set up in the set up menu?

120-20
130-9
140-10
150-19
170-7
190-0
270-9
300-0
320-0
330-2
500-0
530-0
640-12

I'd suggest changing 270 to 3.


Why do you have 530 turned off?

otherwise, these settings has not affeact on the fan.

Does the fan stop when you remove the t-stat from the wall? (Don't turn system switch from heat/cool to off)

I tried changing 530 just for the sake of it.

Well, when I had the tstat off, I removed the unit and the fan was still on. I went to my furnace and threw the breaker and it turned off as expected but when I put reset the breaker, the fan came back on! How is that possible if the tstat is disconnected? I even checked the voltage between G and C and it was 0. The voltage between R and C was 24v.

So I put the tstat unit back on, and with the system set to off, I toggled the fan from Fan Auto to Fan On, heard a switch. Fan stayed on. Then toggled back from On to Auto and the fan went off. So, that's good. But when I toggled it back to On and back to Auto, it stayed on. Kept trying a few more times and the fan won't go off. It is random. Almost like it takes time to discharge something in what I can expect to be a relay in the furnace??

I'd suggest changing 270 to 3.
Why? I have an electric furnace, not a hot water or gas one.

Why? I have an electric furnace, not a hot water or gas one.

It has notthing to do if your are gas or not.. It's more for Cycles per hour (CPH)

When and if you set it the t-stat to emergency heat, the system comes on and off about 9 times an hour, and that's just way too short of a cycle, 3 gives you a better comfort, and longer run time.

Lot of tech suggest changing this to 3 CPH instead of 9CPH.


What is the make and model # on your air handler?

What is the make and model # on your air handler?
Hope this helps:
York N2AHD10A06C

When I went to bed, I left the heat on and once it got to temp, the fan just stayed on. When I woke up, the temp was there and the tstat showed that the heat was off, but the fan never shut. So I tried toggling Fan On and Fan Auto again, hearing clicks inside the tstat with no luck. So I put the Fan to On and then I turned the system to off and then Fan to Auto and the fan finally shut off. I don't understand why the fan is shutting off this time and never the other times. I have to give Honeywell tech support a call today. Any other thoughts?

I'm unable to pull any info on this air handler.

Did you try remove the t-stat off the sub-base when the fan stayed on? If the fan stops when you remove the t-stat, then it's the t-stat.

If the fan stays on, then it may be a stuck relay in the air handler, or a wire shorting out somewhere.

I'm unable to pull any info on this air handler.

Did you try remove the t-stat off the sub-base when the fan stayed on? If the fan stops when you remove the t-stat, then it's the t-stat.

If the fan stays on, then it may be a stuck relay in the air handler, or a wire shorting out somewhere.
The fan stays on when I pull the tstat. When I open the circuit breaker after I do this, the fan shuts off and when I close the circuit breaker the fan comes back on. Makes me believe it is a wiring issue.

But like I mentioned before, the fan finally went off after doing a particular sequence on the tstat. Or maybe I just got lucky. I have to try for repeatability.

With the fan still stuck on, remove the G wire at the t-stat base.

If it still on, try removing the G wire at the air handler. (If you can with out killing the power)

If still stays on, then it's the air handler itself.

With the fan still stuck on, remove the G wire at the t-stat base.

If it still on, try removing the G wire at the air handler. (If you can with out killing the power)

If still stays on, then it's the air handler itself.
I'll try this in a few hours when I get home. What if it goes off?

It depends on where the wire has been taken off.

Let us know when you come back with.

With the fan still stuck on, remove the G wire at the t-stat base.

If it still on, try removing the G wire at the air handler. (If you can with out killing the power)

If still stays on, then it's the air handler itself.
Removing the G wire from the terminal of the tstat did not shut the fan off. Honeywell also stepped through this with me and said that this is a problem with my furnace. I am not inclined to mess with the furnace so I guess I have to call the heating company.

Typically, should there be a delay for the fan shutoff in the furnace? Or should it be instantaneously on or off?

There may be a relay in the air handler (Furnace is gas heating) that is sticking on you, and as you are messing with the power and t-stat, is "jiggling" the relay unstuck.

Air handler don't have time delay like a furnace would have.

There may be a relay in the air handler (Furnace is gas heating) that is sticking on you, and as you are messing with the power and t-stat, is "jiggling" the relay unstuck.

Air handler don't have time delay like a furnace would have.
Thanks for clearing that up. I just assumed it was called a furnace. Is there a way to fix the relay or does it have to be replaced? Does relay sticking happen alot? Can I possibly bang on it to get it to move?

The relay are to known to stick every then and now, I would suggest having it replaced.

The relay are to known to stick every then and now, I would suggest having it replaced.
The tech took a screwdriver to the relay, banged it and it went off. So he replaced the relay and now the fan goes on and off properly.

Thanks for your advice here. Helped solved the problem quickly!

Glad to help out. Now you don't have to worry about getting roasted!