View Full Version : Problems with Evolution A/C (probably stat?)
06-13-2006, 11:12 AM
Hi - I'm seeing some odd behavior with my Evolution thermostat. Because my relationship with my contractor is a bit estranged (see my other
posts), I wanted to see if anyone here could help my understand my problems better before I go out and try to get help. I have an Evolution A/C system in my attic (no heat) with it's own stat in the living area. No zones. I'm noticing two things that concern me:
1) I keep the default fan setting at Medium. This improves air-filtering (we have allergies) and provides a little white-noise at night. However, what I've observed is this: If I OVERRIDE the pre-programmed temp and the stat calls for cooling, it forgets the preset fan setting and operates as if the fan is set to AUTO. Cancelling the override does notchange this behavior. Only if I turn the stat OFF and turn it back on, does it then again respect the user-selected FAN setting. Honestly, this sounds like a firmware bug, and I'm not sure replacing the stat (or a circuit board on the air-handler) would make any difference, so I'm not sure what to do.
2) There is an external thermometer on the compressor and an external temperature display on the thermostat. This reading is usually right-on.
However, sometimes, usually in the morning, it reads as much as 11 DegF too high. I even witnessed the stat display change by 3 degrees at once this morning. (unfortunately, the outdoor unit is in the West corner of the house, so I can't attibute this to direct sunlight). I'm not sure how important it is for the stat to always have the exactly correct temperature. I'm also not sure if it's the sensor or the stat.
I know that one response to this post is "go get a d--n professional to look at it", but I'm curious if anyone here is familiar enough with the system to suggest what could be wrong, or what I could do to debug it further. If #1 is really s firmware bug I may be out of luck, and I don't really have the luxury of dragging a contractor into this unless I'm going to get some benefit from it.
06-13-2006, 11:41 AM
What is the model number on the evolution controller? It is either SYSTXBBUID01 OR SYSTXBBUID01-A. The systxbbuid01 was the 1st series in the evolution line, which is no longer manufactured. All new evolution stats now end in the ľA, which have a new software package. This could be your problem.
06-13-2006, 11:43 AM
i think it's the A but I will look. where is the model # found?
06-13-2006, 12:07 PM
You would have to take the stat off the wall (should just pull off leaving the sub base attached to the wall) the model number is on the back of the stat printed on a white label stuck to the circuit board.
06-13-2006, 12:43 PM
You could turn power off at the Furnace, or unplug it and watch the stat. You might want to have someone else unplug it and plug it back in while you watch the User interface. The first thing that will pop up is version software. There you will see what version you have. If the last 2 digits read 10 you have version (-A). Or just pull the UI off the wall
06-13-2006, 01:01 PM
Fan will go back to it's programmed continuous speed when the next period rolls. Haven't heard of the complaint, but I bet it will fix itself at the next period change.
Also, there is a fan off after cooling feature that drops the fan to OFF for approximately 10 minutes. This allows the coil to drain to prevent evaporation of the water that was just removed from the air. Have you given it at least 10 minutes after the call for cooling?
OA temperature fluctuations causes can be anything from actual ambient interference to electrical noise interfering with communications.
06-13-2006, 02:35 PM
If I am reading you correctly, you are saying that when the unit comes on for a cooling call, the fan speed changes from Medium to what ever it stat wants. If so, it is working correctly. The Low, Medium, Hi are only for continuous fan speeds, not for cooling mode speed. On a call for cooling it will, and is suppose to change speeds. As Jr says, after the call for cooling is completed, the fan will go off in order to let the coil and drain pan empty. It will come back on and operate at your continuous speed after a time delay.
As to the outdoor sensor, being out of calibration will not effect the operation of your unit. If it is only off at times and correct at others, it is most likely being effected by an external heat source (sunlight, fan, dryer vent etc. )
06-13-2006, 07:46 PM
Ok - let me answer all of these:
1) Model SYSTXBBUID01 SW: CESR 131339-08
So I looks like it's the older stat. It was just installed in January. When did the new one come out? Am I entitled to an upgrade under Bryant warranty? It seems like this would be a good idea given its erratic behavior. I'm guessing though, that this was collecting dust at the distributor and not at the contractor. (So maybe the distributor will swap it - see my other thread for why I don't want to ask my contractor).
2) What I'm saying is this: If I never do an override, and leave the Fan on MED. The Fan ALWAYS runs at MED or higher, even when cooling. When I do an override, the Fan runs at whatever the Cooling calls for: Low/High or sometimes Off.
3) Interestingly, I think my 'owners manual' is for the new stat, as it describes features that don't work on my stat. For example: The manual says I can have a separate FAN-speed schedule by pressing the schedule button and then the fan button, but it doesn't work for me.
4) couldn't find a "fan off after cooling feature". Checked the service menus and service manual. If you're sure, can you be more specific (though this is not a problem I'm having).
5) I notice that I can change the airflow from "comfort" to "efficiency" which might have the same effect of keeping the blower at a higher speed, but I'm reticient to muck with things I don't fully understand.
Thanks everyone. I look forward to your thoughts. (any of you Bryant A/C dealers in Eastern MA?)
06-13-2006, 07:55 PM
1. Yes it is the older stat, No you can not upgrade under warranty. The new stat was designed for the new line of equipment that came out earlier this year and really does not add any functionality to your system.
2.When you do an override the fan speed will change. The continuous fan speed is just for the program you are in, you would have to select it for all programs.
3. You do not have the wrong literature. Your control can be programmed for different speeds in each program period. In fact it sounds like that is what it is doing. What this means is that you can select a differen constant fan speed for each program period, not that you can program the fan to do something differently. However you can accomplish a fan program by simply adding program periods. (Did I totally make than mis understandable?)
4. Fan off after cooling is not a programmable feature, it is the default and non changable way the stat works.
5. Do not change your airflow to Efficiency. This just changes the cfm per ton that your air handler will provide. It will work best at Comfort, leave it there.
6. You are wise not to mess with the other settings. What may look simple, could have adverse effects on the operation of the system.
06-13-2006, 08:01 PM
Programmable fan must be enabled for your to program the fan with a period. It's under the service/install menu.
Fan off after cycle isn't in the literature - even literature that's not . I had to speak with a Carrier engineer get the explanation. It occurs after a call for cooling and the humidity is above the cooling humidity setpoint.
-A model has been available since feb/march. You got the right one for the time of install.
When you enter OVERRIDE and select a fan speed, will the fan run at that speed before you get a call for cooling?
06-13-2006, 08:32 PM
Well - i thought that worked -but it didn't. I enabled FAN Programming, and set to MED for all days/ all periods. Now, when I go into override. the fan stays at MED (yea!) but ONLY until the compressor turns on, when it again 'forgets' the Fan program and runs AUTO (The fan runs at low until the house is cool, or I raise the override temp, and then the FAN TURNS OFF). The only way to get the FAN back to MED is to turn the system off, wait, turn the fan to MED, wait,and then turn the system on. (if I turn the system off, wait, and turn the system on, the fan come on for a few minutes and then turns off again, even if the system isn't calling).
It may be that, during normal (non-override) operation, the Fan goes to AUTO when the system is cooling, but the fan doesn't turn off when the cooling is complete.
I suppose the 'fan off after cooling' could play a part in this, but to check I need to ask: Is there any way on this stat to see what it thinks the relative humidity is? I've been unable to find this display.
Anyway, If I can't upgrade my SW, how do I get the fan to stay on MED -all- the time? Are you all sure this stat isn't wacked? thanks!
Also - what can/should I do about the temperature sensor reading high? I have a digital thermometer that is my reference (which i trust as it's been right against our analog thermometers and the weatherman for years). The "outside temp" on the stat can be the same temp as the reference, or up to 11 degrees higher.
I'm wondering if i need to care. Although, I'm concered that low-temp lockout won't work (in-between seasons here the temp sometimes plummets from 60 to 50 before i notice), but I'm not sure how it will affect system operation when it's 75 or 80 out and the system thinks it's 10deg warmer.
Is it likely to be the sensor or the stat? If it's the sensor, is it an inexpensive part and easy to replace for a handy homeowner? (i might be able to get the distributor to send me one).
[Edited by jeffw_00 on 06-14-2006 at 12:29 PM]
06-14-2006, 12:30 PM
sorry - I edited my last response rather than posting a new one, based on new data. so if you read it before 12:30 today plz re-read. next time I'll do a new post.
06-14-2006, 01:50 PM
It sounds like your stat is working properly. Once the call for cooling starts, the fan is suppose to change speeds. That is what makes the Infinity special, it is able to control fan speed. There is no way to manually set the fan speed during a cooling call. It is also suppose to shut off for 5 minutes at the end of the cooling cycle to allow the proper drainage of condensate from the coil and drain pan.
Again, most likely the sensor is being effected by some outside source. Sensors normally do not work correctly sometimes and not others, they are either good or bad. It could be electrical interference or a heat source.
06-14-2006, 01:52 PM
so what should i DO about the sensor - find and reposition it? Get it replaced?
Our Bryant Evolution had an erratic temp display. Turned out to be the temp sensor was left inside the unit, so any heat it generated was picked up by the sensor. I moved it outside the unit. It still gets affected by the morning sun a couple months of the year, but only for a few hours.
06-18-2006, 02:23 PM
If this is the new style equipment like he said it was, the sensor is factory mounted and should not be relocated. If it is the older style you may exactly right. Either way it sounds like some outside source, electrical interference or convection, is effecting the sensor and not a problem with the sensor itself.
06-18-2006, 04:08 PM
I think it's heat from the unit itself. I put my regular sensor on top of the compressor and left it there for a few hours. I'm starting to think
a) the sensor is ok
b) the sensor's reading is influenced by heat from the compressor.
Does it really matter? What does the system use the temp for? (other than low-temp cutoff)
06-18-2006, 04:21 PM
On your straight cooling unit it is used for low cooling lockout, crankcase heater lockout and low ambient fan control. None of these will be adversely effected by the way you describe it only being a few degrees out as all of these are only "cool" weather controls.
06-18-2006, 04:23 PM
thanks - though even in cool weather (high 50s) I've seen it read 5-10Deg high
06-18-2006, 05:22 PM
The few degrees out of calibration will not be a problem for unit operation, forget it.
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