While the Google Nest Thermostat install can be fairly simple on most systems, there are occasions where something goes wrong. We're going to cover 3 common problems and how to solve them quickly and easily. We go step-by-step below, or you can check out the video at the bottom if you'd rather do it that way!
One of the most common issues that arises after a new install is when the system blows out hot air instead of cold air.
Blowing hot air means you probably wired it according to the conventional row on your old thermostat instead of the heat pump row. If you took a picture of the old thermostat's wiring before installing the Nest, go back to that picture and label the wires according to the heat pump side of the thermostat instead of the conventional side.
Head on over to the Nest compatibility website and enter in those wire labels from the other side of the row on your old thermostat. You can also restart the process of adding the thermostat within the Nest app, which will bring you back to the interactive wiring guide. This interactive guide will provide a little more detail and can be handier than the website.
Always make sure to turn the correct breakers off before opening the air handler or performing any kind of wiring.
Make sure you look at the colors of the wires related to the bottom row on the old thermostat, not the top one. Once you get it all wired correctly, the thermostat will detect the right wires and you should be in business, blowing refreshing cold air this time.
The first time I hooked up my Nest, it told me there was no power running to the R wire and the system wouldn't turn on at all. This one is a little more tricky to troubleshoot than the previous issue but is easier to fix. There are likely three possible reasons that might cause this problem, so let's take a look at the breaker first.
You should always make sure your breakers are off before opening the air handler or performing any kind of wiring, which is great for this first step.
While you're at the breaker, check to see if one of the breakers got tripped. Sometimes a breaker will get tripped, which is normally denoted by the switch sitting in-between the on and off locations. Flip any offending breakers off and then on again, then check to see if your system has power.
Sometimes it's not as quick, but is still relatively simple.
My old thermostat had a single R wire, which was bridged to an Rh wire on the thermostat itself. Some others might have an Rc bridged to an Rh or some combination thereof. Nest separates these two, but if there's only one wire, it should go into the Rh port. If that doesn't work, try putting the red wire in the Rc port to see if it registers.
My system, of course, ended up being the least obvious issue, which is a blown fuse found inside of the air handler. Mine requires a few screws to be removed before I could get the door off, but once I popped it open I found a small 5V fuse inside that was obviously blown. Replace that bad fuse with a good one, which will only cost you a few bucks at the most and can be found at your local hardware store, close the system back up, turn those breakers back on and you should be good to go.
The first time I installed my Nest I found that the thermostat itself didn't click very easily into the wiring disc that was screwed into the wall. I found that the mounting was frustrating and doesn't click in very well, and I constantly had issues even just setting the thermostat up because the bottom wouldn't click and then it would eventually reboot the thermostat.
What I found was that the wires behind the unit were getting in the way. My old thermostat had a bit of a rats nest of wires inside and just needed a fresh snip on the ends.
Start by pulling the thermostat off the mounting disc and making sure the mounting plate is secure. All of these wires need to be flush with the inside part of the disc or else the thermostat doesn't have a way to click in and may even fall off the wall if not inserted properly.
Take a picture of your current wiring just to cover all your bases. Bonus points if you label each wire as you pull it out. Use a pair of wire cutters to snip each wire back a bit and restrip them so that you've got fresh copper to work with and, most importantly, less mess.
The original length of my wires made them protrude a bit from the wall, thus keeping the thermostat from properly clicking into the base.
It's important to note that the button on the front of the Nest Thermostat isn't actually a button at all, it's just a pressure point that pushes the whole unit inward instead, meaning if the thermostat isn't fully connected to the button or flush with the wall, you won't be able to click the thermostat in to select things. I'm not a huge fan of this design, but it is what it is.
Get those wires reinserted and nice and flush with the inside of the disc, and you should find the thermostat is super easy to pop on the base and go.