Thermostat causing HVAC to freeze?

I have a 6 year old home. The inside HVAC has frozen maybe twice in our 6 years. I now change the filter monthly and have cleaned the internal coils once.
Ever since changing to the Wyze thermostat we are now finding our internal HVAC coils frozen every day or two.
Is this possibly being caused by a bad thermostat?
Every function is working correctly and we are using the same temperature “holding” as our older thermostat.

Thoughts? I am out of town for a couple weeks. Have thought about putting the old thermostat back on to see if it solves the problem.

Generally this would be caused by insufficient airflow. Is your blower fan running properly?

Another possible cause could be the system being overcharged. Your thermostat wouldn’t be the root cause, but an extended run time from your thermostat could maybe cause it to happen more frequently. You need to find the root cause of the issue, but you could move your temperature differential setting to 0.5 degrees (assuming it is 1 now) to see if reduces the issue.

The blower is running normally to me. I do not know the charge level.
Before calling an HVAC service call I will change the thermostat back and see if the problem continues.

Just had read on several forums a bad thermostat can cause this issue and wanted to see if anyone else had seen this.

Unlikely thermostat is the problem.

Check your refrigerant level and for fine, fine leak.

Ever clean coils of your outdoor unit.

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I agree with Speadie, that insufficient airflow can cause this. A dirty filter or loose belt can cause low air flow. Also, if most of the registers in the house are closed, the airflow will be greatly reduced. Maybe give the registers a look.

Another cause can be low refrigerant charge, maybe caused by a leak. Lower pressures in the refrigerant system mean lower temperatures. If this is the situation, a good refrigeration tech c an measure the pressures and add refrigerant if necessary, and also help you to find the leak.

I think it is likely caused by the thermostat. You can see my post here: Thermostat does not cycle. The wyze thermostat does not cycle the way a thermostat is supposed to. It just runs flat out (in my case, for hours), reaches the setpoint, then shuts off again for hours. What it is supposed to do, is cycle approx 4 times per hour, with longer runtime the farther you are from the setpoint and shorter runtime when you are closer. The wyze doesn’t do that.

which also means that air is not circulating a lot of the time and temps in the house are very uneven. I’m hoping wyze realizes the problem here and can fix it by a firmware fix because this is not how thermostats are supposed to work.

This is not an accurate representation of how a thermostat should work. The wyze is doing the correct thing, Running until set-point is hit and then waiting until the threshold temperature is hit then running again. Running when not called (4 times per hour ?) makes no sense. Your system is severely oversized or you have poor airflow if it is running once every few hours,.


Then again, electric thermostats, like those that have been used for the last 100 years, don’t cycle based on time, and don’t freeze coils.

I don’t own a Wyze thermostat yet. Is the switching differential adjustable?

You’re wrong. Anticipation and cycle rate | Contractor

With all due respect, what those documents actually say is not what you think they say. Some of them are cycle rate limits to prevent too rapid cycling (cycling less often is better, cycling more often shortens the life of the compressor, contactor, fan motor, and belts). Most of those are recommendations for how tight you set the differential on the thermostat, and are not about some kind of timer in the stat with the exception of the one that protects the c ompressor, or “prevents over-cycling,” to quote the article. Generally, the rest say “this is a guideline for the maximum rate that you should be cycling the equipment on a design day.”

The cycle limit timer is a little more complicated in actuality. It really is intended to give the refrigeration system enough time for pressures to equalize after it turns off, so that the compressor doesn’t have to start against high pressure. It has nothing to do with comfort.

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I’m not even going to try to educate you, You obviously “know” everything already.

Yes, between 0.5 degrees and 3 degrees F.

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What he is not understanding, Speadie, is that the only timer in his list that has anything to do with comfort is the anticipator, and the anticipator has nothing to do with cycle rate. All of the rest are to protect the equipment, and cause it to cycle LESS often, not more.

I wonder if he has his differential misadjusted to 3. Maybe he should put it at 0.5