I have a PTAC unit in the room above my garage (Amana PTH123A35AC) that I’m trying to connect a thermostat (Honeywell 50018270-001) to. These are my current connections:
| PTAC | Thermostat |
|---|---|
| B | B |
| C | C |
| GL | G |
| R | R |
| W2 | W |
| Y/W1 | Y |
| GH | Unused |
| Unused | O |
| Unused | Rc |
The only thing that’s not working is the cool setting. Heat and the fan are working fine. I have tried connecting R to Rc and B to O, but neither worked. I’m fairly certain I have something incorrectly wired here, but I’m just not sure which connection.
PTAC Serial Number Decoded:
- PTH: Standard Heat Pump PTHP
- 12: 12,000 BTU/h, 60Hz
- 3: 230/208V, 60Hz, 1 Phase
- A: First Design Series
- 35: 3.5 kW (230/208V)
- AC: Standard Model
Does anyone have any ideas as to why the cool setting isn’t working?
https://hvacdirect.com/media/hvac/pdf/AMANA-PTAC-Service.pdf
https://digitalassets.resideo.com/damroot/Original/10003/69-1775.pdf
Those are the ones you have, right? Check the wiring for each function to make sure the thermostat and unit agree. Then check the configuration on the unit and thermostat to make sure it’s correct. Then run a system test from the thermostat.
You should also be able to just short Y to R to turn on the compressor.
But I’m not a professional, and I’ve never worked with anything more than a furnace with a fan. But it looks like the principle is the same.