We have a heat pump that is about 16 years old with the air handler in a knee wall attic. We had some insulation work done this fall that included sealing our ducts and since then we noticed a few things: A window in the room attached to the knee wall would rattle a lot when the blower was running. This window would occasionally rattle before the ducts were sealed, but no where near as loudly or as often. There are areas close to some walls or corners where you can hear a low frequency rumble. It feels more like a pressure in your ears than a sound. If I partially close a door and alter airflow it reduces the rumble, so I think this is more airflow than mechanical vibration transmitted through the attic.I'm not sure if the window rattle is mechanical vibration or from whatever is causing the "pressure spots". There is definitely some vibration coming from the blower fan, and the blower also has quite a bit of dirt / mold build up (the coil looks pretty clean though). When the technician came by for winter maintenance he said some amount of vibration in the blower fan is always going to happen and what we have was normal for a unit this age. The blower is apparently variable speed, but the previous owner had it set to always run at high speed (maybe that was needed when the ducts were less well sealed). So he set it back to only use high speed when needed. He also adjusted the risers to help improve the isolation between the unit and the attic. With the fan running at lower speed, we don't get any window rattles and the "pressure spots" are mostly not noticeable unless you are really paying attention. However, when the motor ramps up to high speed we still have the pressure spots and occasional window rattle. The window rattle does not always happen when the blower ramps up, so I'm thinking maybe it is mechanical vibration that has been reduced. The technician said he wouldn't bother with trying to take apart the blower wheel and cleaning it out. He wasn't sure it would help with the balance of the fan and said it's easy to make things worse if you aren't carefully with cleaning it. He suggested if would be better to just put the money towards replacing the whole blower assembly including the motor. Since it's a variable speed motor, this is fairly expensive. One thing he didn't discuss was just replacing the blower wheel, but not the motor. If the motor is still working then only replacing the blower wheel is a lot cheaper and might address any balance issue. I'm looking for some advice on repair or if there is any follow up I should have with the technician. Should I just try to clean the blower and see what happens? Would it a bad idea to replace the blower wheel and leave the original motor? If I don't want to replace the whole assembly, should I just do nothing (and deal with the occasional rattle)? I got the sense from the technician the amount of vibration was normal for a unit this age and wasn't likely to have a big impact on the overall life of the heat pump or blower at this point. It also wasn't clear if anything we were noticing was caused by the blower fan vibration or just the increased pressure in the ducts now that they were better sealed.

We have a new Trane heat pump installed last February, so less than a year old. This year we have noticed a strong odor coming from the vents when the heat is running and the outside temperature drops below 34 degrees (give or take a couple degrees). The blower unit is in the crawlspace which stays dry with a steady low humidity. Last winter when the unit was installed there was no odor during the heat cycle. The Trane installers did come out and thoroughly inspected everything including the coils and drain pan etc. and put it through several cycles including the defrost cycle, but could not replicate the issue, although it was in the middle of the day and the outside temperature was above 45 degrees when they came out. Now every time the temperature drops in the 30’s, the smell is back. They said they’ll had to come back when it’s colder during the day to try to smell the odor since they couldn’t replicate it. Any insight? We can’t be the only ones with this issue.