I have a new Carrier package unit which we bought 5 months ago. All of a sudden the blower does not shut off and constantly runs. It occasionally cyles off and on. The compressor does not kick in and it shouldn't because it is set to turn on at 77 degrees and the house is an average 70 degrees. It began happening on what we Floridians call a cold night, 60 degrees. It is connected to a Riteaid electronic programmable thermostat we bought at Home Depot. It does not have a heater. I cannot find anything in the thermostat that could be causing the problem. What in the world could be causing this blower not to shut off? Blown fuse in the AC? The only way I got it to turn off is by cutting the power to the unit. Any help will be greatly appreciated.

If the unit is new it is under warranty. If you mess with the unit it can cause the warranty to be canceled. Why take the risk. Call the company that you bought it from. Most dealer warrentys parts and labor is one year form date of purchase.

If the unit is new it is under warrenty. If you mess with the unit it can cause the warrenty to be canceled. Why take the risk. Call the company that you bought it from. Most dealer warrentys parts and labor is one year form date of purchase.

The problem is that the A\C was installed by myself and a buddy of mine from work, yes I know mistake number 1. Buddy of mine got the A\C wholesale through his dad's company. Company he bought it from won't honor anything if I don't know what is wrong with it.

Blower relay could be the problem.

It could also be the thermostat telling the blower to come on for some reason. Test this by disconnecting the G wire from the thermostat and see if the blower still runs sometimes

I have an older carrier unit in Michigan. The blower will not shut off and continues to blow when the flame is off cycle. The heat is fine but I am worried that this is nit efficient and could damage the motor. Is this a fuse? Do I need a new ignition module?

Andy

Disconnected the G wire to see if the thermostat was making the blower turn on for some reason and after disconnecting the G wire, the blower continued to run. I even reset the thermostat by pressing a small reset button in the Ritetemp thermostat and nothing, blower still runs continuously. Defective thermostat?

If you disconnected the G wire from the tstat and the blower still runs it is not the tstat. It has to be a stuck relay OR something is wired wrong like the thermostat wires are shorted causing the problem.

I will check the wiring and the blower relay. It ran fine for months and this started happening when the outside temperature dropped. Is it safe to assume that it could be a bad relay? I'll check both and let you know the outcome. Thanks for your help.

It could be a bad relay but usually when they stick or the internal parts burn together they never turn off after that happens. You said it would sometimes turn off so that complicates the situation. Does the thermostat have a recycle schedule you can set just to circulate the air at different periods? Some thermostats do offer that as a option in the setup menu.

Checked the wiring on the tstat as per the manual and it all seems to be correct. I only have three wires going to the tstat, Y=yellow, RH=red, G=green so it seems to be a bad relay. Would you have any idea where this relay would be located on a Carrier package unit? I just turned it back on and I'm going to see if it turns off which I have a feeling it will not, I'll let you know. Given the fact that it started happening all of a sudden after a few months would point to a relay and not wiring, wouldn't you agree?

Well, off to eat Thanksgiving with the family, wish you and your family a happy thanksgiving and thanks again for the help.

If you disconnect the green wire on the outside unit and the blower still runs then the relay has to be bad in my opinion since this is a package unit and everything is outside except the thermostat. Now if you disconnect the green wire in the outside unit and the blower shuts off then you know they thermostat wire or thermostat is causing the problem.
Does this unit have heat?

I have left the AC on AUTO fan and COOL for 24 hours and the blower cyles on and off randomly without engaging the compressor. I am going to try what you said and let you know.

Replaced the tstat and it seemed to have fixed it. I think it was a defective thermostat. I replaced the stat with a plain jane non-programmable one. Thanks for all your help.

Good deal. Glad to see it is working. Some thermostats of the program type will allow a setting for the blower to run every 15 to 60 minutes depends upon how programed.