THE SHORT QUESTION:
Does anyone know where I can find system drawings / specifications for AprilAire zone control dampers and provide troubleshooting guidance on how to detect and correct if a damper is stuck closed? I would like to verify operation of the damper and possibly disable (by mechanically limiting its ability to close and disconnecting it from the zone controller).
THE LONG HISTORY:
So I have a relatively small (1700 SF) summer home with most of the SF on the main level but about 1/4 to 1/3 of the SF on the second floor under the gable roof. The HVAC installer installed a single Heat pump behind the kneewall on the second floor but added an Aprilaire zone controller and two thermostats and associated dampers. From the beginning I thought this may have been overdesigned since the stairwell is open and the ability to get an appreciable difference in temperatures was unlikely (and now I have the added concern of making sure my wife doesn't have the heat on on the main level and the A/C on on the second level or vice versa).
Anyway, for 3 years this has worked reasonably well (the board fried itself once and we had a second issue which was traced to the thermostat wire being stapled to the wall too tightly [which probably caused the first problem] but both were within the warranty period) but two weeks ago I noticed that the main level would not keep cool during the heat of the day and there is nearly no air coming out of the vents on the main level (there is some air coming out but it seems like it is the "bypass" only) which contrasts with the blast that is easily felt from several feet away previously (it is a 4 ton unit... also the airflow on the second level is VERY strong). Since we had already had a few problems with the controller and I have spent a reasonably time with a multi-meter in other areas I decided to take a look myself and I spent some time with the cover off and various thermostat settings and it seemed that the control board (AprilAire 6303) was working properly (damper voltage to the [NC] terminals went to ~24 VAC when the zones should be open [for either a call for "Cool" or the fan switched to "On"]). The dampers are at a place that are inaccessible due to their location behind the kneewall without cutting a hole in the wall (more on this later). For the record the A/C unit itself seems to work fine and blows cool air to the second level which is easily enough to keep the house cool at night and most of the day.
So my wife is one that accuses me of trying to do too much on my own and that I should get a professional in to diagnose and fix the problem so I call the original installer to come out and take a look with the specific instructions to verify proper operation of the dampers.
I get a call from the technician when he is at the house and he indicated that he thought the airflow was fine. Since I am not there it is hard to dispute what he is saying but I ask him to try various scenarios (Zone 1 on Zone 2 off, vise versa, fans only, etc.) and then have him verify that the airflow seems right on both levels under all scenarios. He indicates that he is getting airflow and unfortunately I have no option but to assume that this self-healed in the two days it took for him to get there. Since he is already there I asked him to verify that the refrigerant pressure / levels were appropriate which he does. Then about two hours later I get another call from him indicating that he waited around to make sure the house temperatures responded as he expected and agreed that the lower zone wasn't blowing properly and spent an hour getting into the location of the dampers and then "Found strap on motor loose and repaired motor" (as described on the invoice) and now realizes what I had been talking about previously but assures me that the airflow is good now. So I am a little upset that he was dismissive of my concerns originally but am happy to know that it will be working the next weekend when we have friends coming to the house. (I also got a lecture about letting the thermostat settings be more than a few degrees apart from each other because that is not how the system should be used and the ducting for neither zone is sized to take the full load of the a/c unit which goes back to my original view that this is overdesigned [perhaps poorly designed] for the needs).
So I arrive on Friday and immediately check how the system is working and find that there is still no air coming out of the lower level vents. I don't know if he fixed it and it broke again or if he just fed me a line. Either way I am stuck with a system that doesn't function the way it used to and a $217 bill.
Despite my wifes view, I don't plan to spend $217 every time this damper sticks shut so need to take matters into my own hands.
So my question is, "Does anyone know where I can find system drawings / specifications for AprilAire zone control dampers and provide troubleshooting guidance on how to detect and correct if a damper is stuck closed? I would like to verify operation of the damper and fix it the first time but if it turns into a recurring problem then possibly disable it (by mechanically limiting its ability to close and disconnecting it from the zone controller)."
I don't know the exact size but suspect it is one of the dampers found on this page:
and if I had to guess I would say specifically something like:
16" Diameter Motorized Damper, Normally Open, Power Closed Damper, #6616
I have looked at the literature I could find and nothing gave me much of a view of what I would expect once I pulled the cover off the damper so am hoping someone here can help.
Any help would be appreciated.