I have an Amana AMH80804BN with a Nest thermostat (wires Y,C,Rh,W,G) and a 3 ton AC. I have been having issues with the AC portion the furnace (heat) seems to work fine.
The AC will start out the day working great! Cold air blows out it will run for an hour or two and before it gets to temp the blower motor shuts off while the compressor continues to run. Then at this point the evaporator coils tend to freeze (sometimes).
Then, the blower motor seems to try to run every 10 minutes or so. The blower spins up, runs at a low speed for a few seconds, and turn off again.
Eventually, after many attempts the blower fan will kick on and the AC will begin to cool again then rinse and repeat all day.
Also a strange and likely connected issue is that I cannot turn the blower fan on from the thermostat I turn it on from the thermostat and nothing happens.
I can power cycle the whole unit but doesn't seem to fix anything.
Cooling is adequate on most days with this issue when the outside temperatures are 70-85F but when it's hotter outside (above 85F) the AC can't keep up and it never gets colder than 80F inside.
Troubleshooting steps I've taken:
- Multiple google searches. The issue seems to be unique to my case.
- Cleaned my evaporator coils and compressor coils. They were pretty dirty and neglected but issue continues even though now they are squeaky clean.
- Full wires check. Checked AC sender wires, thermostat and thermostat on the furnace side.
- Removal of 'saver switch' my electric utility company added a saver switch that turns off the compressor during peak times of the day. I have bypassed this.
- Hardwired the blower fan. Tried to direct wire the blower by crossing the green and red thermostat wires.
- Checked fuses, breakers and wiring at the unit itself.
- Checked on-board diagnostics (solid red light showing)
- Bypassed the blower limit sensors
- Quick check of air duct blockages