Pro1 T855 Thermostat Troubleshooting Guide

Like many other thermostats, your Pro1 T855 thermostat may sometimes malfunction. If this happens, you want to troubleshoot your thermostat to get it working properly again.

Pro1 T855 Thermostat Display

If your Pro1 T855 thermostat is not working properly and you’re looking for tips to troubleshoot the issue, this post contains some tips to help you achieve that. Let’s get started.

In short, a quick way to resolve common issues with your Pro1 T855 thermostat is to power cycle the device (remove the batteries and put them back in).

That said, let’s go into more details on how to troubleshoot your thermostat.

Troubleshooting Your Pro1 T855 Thermostat

Check the Batteries

Is your thermostat not turning on your heating or cooling system? Is it reading the wrong temperature, or the display is blank? Issues like these may happen because the batteries in your thermostat are running low.

If you notice any undesirable operation with your Pro1 T855 thermostat, the first place to look is the batteries. Remove the batteries from the thermostat, then wait a few seconds and insert them back properly.

If that doesn’t help, the batteries might be low. Your Pro1 T855 thermostat features a low battery notification—the low battery icon will appear on the thermostat screen once the batteries are running low.

Check your thermostat display for the low battery icon. If it’s there, get a new set of alkaline batteries and replace the old ones.

However, your thermostat may not show the low battery indicator sometimes. This may happen if the batteries are bad. So even though you don’t see the low battery indicator, go ahead and replace the batteries.

Note that the thermostat only uses AA alkaline batteries. Do not use lithium or rechargeable batteries.

If your thermostat doesn’t work properly after replacing the batteries, proceed to the next troubleshooting step.

Reset the Thermostat

Another way to resolve common issues in a Pro1 T855 thermostat is to reset the device. This usually helps to fix internal bugs or incorrect settings causing the problem.

To reset your Pro1 T855 thermostat, go to your circuit breaker box and locate the switch that controls your thermostat. It’s usually labeled “HVAC” or “AC.” Next, flip the switch off. Then wait 30 seconds and flip it back on.

You can also reset the thermostat by installing the batteries backward. Then wait 5-10 seconds, remove the batteries and install them properly.

Your thermostat has been reset, and it should work fine now. If not, continue to the next step.

Clean Your Thermostat

Sometimes, all that’s needed to get your thermostat to work properly is to clean it.

If the inside of your Pro1 T855 thermostat is clogged with dirt/debris, the wires may not get good contact with the terminals—which means current won’t pass through the wires properly.

You’ll have to remove the thermostat cover and clean it with a soft cloth. If needed (if the dirt is caked on the coil/wires), get a soft brush. You may also use a vacuum hose to remove dust or dirt from your thermostat.

Inspect the Wiring

Your thermostat won’t work properly if the wires are not properly inserted into the terminals.

You want to check to ensure that all wires are in place. Check for pinched/burned wires and replace them if needed.

However, wiring issues are usually complex. If you’re not sure how to check and fix wiring issues, get a professional to help you.

Closing Thoughts

If you’ve tried all the fixes above and the problem persists, call a professional to check your thermostat and recommend fixes. Sometimes the issue may come from your HVAC system and not your thermostat. The expert should be able to tell after running a check on the thermostat.

Also, you can contact Pro1 Customer Support and report the issue. If the thermostat is bad, you might get a replacement—depending on the warranty terms.

You may also like to see how to troubleshoot Pro1 T705 and Pro1 T701 thermostats.