When the set temperature is reached the outside condenser shuts off but the air handler keeps running (for hours). The only way I can turn it off is by throwing the circuit breaker. The problem started a few weeks ago. I replaced the batteries in the thermostat and everything was working fine. Now the problem is reoccurring.
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Re: the air handler won't shut off
As long as the t-stat fan switch is in the auto position the problem sounds like fan relay is stuck. It looks like a little black box about 2 inches square. Has 5 positions on it two of them are for 24 volts. Be sure you turn off power before pulling it out. Make note of the arrangement of the wires maybe label as you remove them. ken
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There is probably a stuck "contactor" on the condenser. Where the line voltage wires from your house connect to the unit there is a contactor. That part has a small set of contacts/points that open & close upon demand allowing voltage to feed through the unit. Those points are welded/stick together. A 2 pole 40amp contactor should fox it.
There's a small 3 amp fuse in the air handler (indoor) that protects the control transformer (there should also be internal circuit breakers and a disconnect outside). The condensing unit (outdoor) is protected by an outside disconnect and circuit breaker.Be sure to shut the power before messing around in the air handler.
Sounds like the contactor in the condensing unit is stuck. That is why it will not turn off when the thermostat is satisfied. If the inside air handler is not blowing and the outside condensing unit is running, then this will cause the inside coils to freeze up rather quickly.
The contactor is located in the outside condensing uni in the electrical compartment.
If it is sticking it will need to be replaced.
Hi, here is the theory on the reset button on Air Conditioners. They reset via the breaker panel box in your house. Check that first before anything else. However if your unit is popping breakers, it is because the rating for the breaker is incorrect, or there is something that needs servicing usually in the outside unit called the condenser. That piece contains the compressor. A faulty compressor and pop the breaker. Or If the condenser fan that blows over the coils of the outside unit stops (common failure) The compressor will overheat and shut down. That may not trip the breaker but the house will get hot anyway. Usual action for this is to replace the condenser fan motor and starting capacitor. Make sure the speed rating and directional rotation for the replacement motor is the same as the motor removed. There are other reasons why the system won't come one fully. If the wall thermostat is digital and does nothing. including turning on the fan. There will be a small fuse located on the circuit board of the air handler (part of Air Conditioner mounted inside the house. It houses the circulation fan). That fuse could be blown. That one shuts down just about everything. On air handlers mounted up into the attic crawl space there is an overflow pan. This pan is mounted directly below the air handler. This pan can fill with water when the drain pain contained inside the air handler starts to overflow because the drain system to that is clogged. There is a "float switch" mounted in the overflow pan wired to the system in such as way as to shut down the entire AC system if that pan fills. The handling is to clear the obstruction in the Drip Pan inside the air handler. Then remove enough water from the overflow pan and the AC will run as though nothing has happened. If you have more questions, write to me on this site. One thing more. The capacitor alone in the Outside condenser unit can fail and that will stop the condenser completely if it is of a "split" design and used for both the compressor and fan. When replacing this unit alone, ALWAYS find the same specification part. I hope this helps, Have a Happy New Year, Mark
There is a built in delay on all HVAC systems to evacuate conditioned air (hot or cold) from the ducts -- it's just more efficient that way... but if it's staying on for more that 4-5 minutes at most then there may be a problem with the fan relay... or possibly a limit switch.
This is due to thermal overload,Which can be caused by low oil in the compressor,the fan has stopped running on the unit outside,Dirty coils,or just a worn out compressor.Although this is thermal overload,It has nothing to do with outside temperature,But rather the internal temperature of the compressor itself.
the air handler is in the attic or in a closet right? most likely the drain switch mentioned is in a pan located underneath the air handler, the switch is actuated when the condensation drain tube is clogged, ( when it cannot drain the water out of the pan), the float switch is actuated and the unit shuts off to prevent any more condensation, thus preventing overflow into your house/apt. the drain line can be sucked out by using a simple wet/dry vacuum of any kind from the end of the drain line ( usually a 3/4 inch PVC pipe located somewhere outside ).