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Need some help connecting a thermostat (lemmy.world)

submitted 1 year ago by [email protected] to c/[email protected]

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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?

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[–] [email protected] 2 points 1 year ago* (last edited 1 year ago) (1 children)

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.

[–] [email protected] 1 points 1 year ago

I have no idea why I didn’t think to read the thermostat manual. I have read this PTAC manual so many times trying to figure this out.

I’ll give this a shot! Thanks man!

[–] [email protected] 2 points 1 year ago

Update for anyone who finds this post.

I think this was the wrong thermostat for this type of AC. I went out and got an Ecobee to attach to the unit and it’s working great! I did have to call Ecobee to find that I had to change the O/B setting from its default but it’s working like a charm now!