Bizarre Temperatures on AC Thermostat

Jamie M · 08-25-2020, 04:57 AM

We have been experiencing bizarre temperature readings on our Zone 1 Thermostat from Coleman 47000 Series Roof AC unit. Here is a picture attached.

At the same time, this is what Zone 2 looks like. The current temperature shown here reflects the outside ambient temperature.

We're on 50 amp shore power at the time as this last picture shows.

The temperature hops all over the place. Sometimes we can run the AC if we can get below the temperature reading. But it bottoms out at 30 degrees.

Any thoughts?

BobC · 08-25-2020, 08:58 AM

Although I have no experience with your thermostat, I'd suspect a bad sensor or something has gone amiss with the sensor's mounting at the sensing end. You might want to see if there's an easy way to switch sensors on the thermostat's circuit board and see if the issue switches zones. That would confirm that the sensor (or its mounting) is the culprit.

If you're lucky, each sensor has a clearly labeled plug and socket. Otherwise, you should be able to find a diagram of the board online.

**creativepart** · 08-25-2020, 11:36 AM

FYI, I fixed your photos for you.

Here's a hint, to have your photos show up in the correct orientation you need to do one of two things.

1. When taking the photo don't hold the phone vertically. Hold it horizontally and make sure the volume buttons are on the bottom and the home bottom is to the right.

2. For photos you've already taken vertically it's not as easy. You have to download them to your computer, rotate them 90 degrees clockwise in a photo editing program and then save them. Then when you upload them they will appear correctly.

I used method number 2 for your photos. So method number 1 is by far the easiest way to go.

**creativepart** · 08-25-2020, 11:42 AM

About your problem - I"d say you have a bad thermister in the room with the bad reading. You know... those tiny black plastic dots on your wall in your bedroom and in your living area?

You can unscrew the bad one and make sure the wiring is correctly attached. If it is perhaps you need to replace one of them? They cost $15 or so.