The replacement bpard for the HH84AA009 is supposed to be the ICM 275
the icm275 has newer compact relays and some operational differences, to quote the manual:
"Operational Differences and Added Features
The following is a description of the slight operational differences and added features. Refer to ICM275 Component Layout (Page 3) for location of control center components.
Operation with new blower and humidifier relays:
The previous design control centers used a SPST-NC or DPST-NC heating fan relay (HFR of E2) and a DPDT cooling fan relay (CFR or 2F) for blower and humidifier terminal operation. This new control center uses a SPST-NO blower relay (BLWR) and a SPDT blower speed change relay (hi/lo) for blower operation, and a SPST-NO humidifier relay.
1. The low-speed blower will not operate on a transformer failure as on previous designs.
2. If JW1 jumper is cut between R and GH terminals, a constant low-speed blower will occur without any thermostat inputs to the control center. A GC or Y signal to the control center will not bring on the hi-speed blower for cooling operation. JW1 jumper must not be cut on cooling applications.
3. The humidifier H terminal is energized with low-speed blower operation. In cooling operation, the humidistat and humidifier water supply should be turned off to ensure the humidifier does not operate."
are there any wiring modifications needed?
after replacing the board, blower works just fine, when stat is set to "on"
the cooling will work fine as long as the fan setting on the stat is set to "on"
The problem is that when the stat is set to auto, the blower will go on, and then after a minute or so when the cooling kicks in, the unit will "reset" and try many times what seems to be a false start.
anyone have experience with this newer board as a replacement of the originals?