Central A/C Unit Shutting Off Blower ?

The guy has been out twice for this in the last 3 weeks. The last time, (last week), he installed a new thermostat, and yesterday afternoon it happened again. The unit runs fine, and blows ice cold air. But in the late afternoon, (the warmest part of the day), The blower will shut off while the unit itself keeps running, with no air being dispensed from the vents.

If I shut it down and wait for everything to cool down, it cycles back on and blows ice cold air again. So it has to be something on the roof unit that is causing this, and it appears to be heat related. A relay, or a solenoid, or perhaps the blower motor itself is getting too hot and shutting the blower motor off.

Then when it cools down it's back to running fine. The unit is an Amana that was installed by the previous owner in 2004. I have owned the home for the last 7 years, and this is the first issue I have ever had with it. Does anyone with HVAC experience have a clue as to what I'm looking at here? Thanks in advance.

Is there a chance that a float switch on the pan is cutting off something?

billt460 said:

The guy has been out twice for this in the last 3 weeks. The last time, (last week), he installed a new thermostat, and yesterday afternoon it happened again. The unit runs fine, and blows ice cold air. But in the late afternoon, (the warmest part of the day), The blower will shut off while the unit itself keeps running, with no air being dispensed from the vents.

If I shut it down and wait for everything to cool down, it cycles back on and blows ice cold air again. So it has to be something on the roof unit that is causing this, and it appears to be heat related. A relay, or a solenoid, or perhaps the blower motor itself is getting too hot and shutting the blower motor off.

Then when it cools down it's back to running fine. The unit is an Amana that was installed by the previous owner in 2004. I have owned the home for the last 7 years, and this is the first issue I have ever had with it. Does anyone with HVAC experience have a clue as to what I'm looking at here? Thanks in advance.

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You said it yourself- these motors are thermally protected, so it's likely shutting down and restarting once it cools.

Someone is gonna have to go up there and see if the fan motor has voltage when it's not working...

Well, he just left. It was a bad relay switch. He was here for almost 2 hours checking everything 11 ways to Sunday. He is confident this was the issue, so hopefully the problem is solved.

He also gave us a price on a new Mitsubishi Mini Split for our bedroom. $2.5K to 3.0K installed. I think I'm going to go with it. That way we'll be able to keep the bedroom nice in cool, while minimizing the load on the main system at night. It won't be long before we're in the bowels of Summer out here.

liliysdad said:

He also gave us a price on a new Mitsubishi Mini Split for our bedroom. $2.5K to 3.0K installed. I think I'm going to go with it. That way we'll be able to keep the bedroom nice in cool, while minimizing the load on the main system at night. It won't be long before we're in the bowels of Summer out here.

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We have an addition on our ranch house that is 13x24' and it only had one vent and return. Combined with 1950's lack of insulation and flat roof it was always a bear to keep comfortable in both summer and winter.

We added a mini-split a few years back and have never looked back. Cheaper bills overall, less load on the main system, room is comfortable, etc, etc.

DaveW

Keep us posted

Run blower "on" the on position on thermostat. Let the fan run for a few days. If it doesn't shut off it should point to another problem.