PTAC temp sensor not working


Old 08-12-15, 01:30 AM
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PTAC temp sensor not working

I have a Frigidaire FRP12ETT2R PTAC unit. I'm not sure why but the temp sensor doesn't work properly. The air conditioner will cycle on but after it turns off the temp sensor turns down about 5 degrees. From say 75 degrees to 70. The apartment ends up heating up and the temp doesn't change and the unit won't cycle on. Somehow the temp sensor is probably reading the cool air inside the unit and I'm not sure how to fix it or what the sensor is exactly.

Can anyone tell me how to fix it?

I should also note that as soon as I take the cover off the unit the temp sensor starts heating up to room temperature. It's a bit weird.

Filters are clean and I cleaned out all the dust in the vent slots on the cover.
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Old 08-12-15, 07:05 AM
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Are you talking about the room thermostat?
Old 08-12-15, 09:11 AM
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With the cover off, make sure that the thermostat switch is set to standard and not remote on the board located just under the temp. display. Or vice versa if you have a remote thermostat in the room. It will be a little slide toggle located near the dip switches and fuses.
Old 08-12-15, 10:37 AM
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Turn the fan to on and see if this will fix the issue.
Old 08-12-15, 12:57 PM
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I think it's the thermistor. I don't have a thermostat. The wire went along the front of the coil. I tried adjusting it a few different ways. Odd that when I barely squeeze the hard part the temp rises I tried setting that part in the plastic clamp. Still didn't work. I have it hanging out of the bottom of the air conditioner now and it sort of works. The temp doesn't drop after the air conditioner cycles off.

I'll check the board again.

The fan use to be on 24/7 and I flipped a dip switch and made it so it cycles off with the air conditioner. I've only had this air conditioner for a week and a half but I got tired of the fan being constantly on. I know it use to work with the fan on all the time. I could hear the air conditioner click on and off. Sucking in room temperature probably kept the thermistor's temp from dropping but I'm worried about wasting electricity from having it on all the time. I'm assuming the fan uses a lot of electricity and it's so loud. It's annoying.

There should be a way to set it up so it works without the fan needing to be on 24/7 right?

Edit I looked at the control board on the PTAC and there is sort of a 2 switch dip switch on the opposite side and next to where the main dip switch baord is. Both are in off and I'm not exactly sure what turning them on does. It doesn't say in the manual. The manual just has the main dip switch board that has 7 switches on it.

Here is the manual. It's on page 9

Would changing anything with the control board affect the thermistor at all?

Last edited by Travis17198; 08-12-15 at 01:28 PM.
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