I have older model Whirlpool Brand Furnace, which was doing fine until recently. Just yesterday, I noticed that the a/c blower/condenser unit outside is coming on at the same time the furnace is coming on. (i.e. I want the furance to run, but not the a/c condensor) I've researched the problem to some degree, and can only narrow it down to possibly a faulty relay swith, or fan-limit switch, or some other problem. So, my questions are:
1.) Why is the a/c condenser/blower outside coming on while the furnace is on? and more importantly, 2.) What do I need to do to fix it myself(i.e. without calling a service repair man)? Thanks, any correct information will be appreciated.
Rick

That seems unlikely. I hope I won't insult you by asking if what you have is a heat pump rather than a furnace. 2 ways to recognize a heat pump is the outside unit being up on legs, and you don't use gas or oil. The third thing is that the outside unit must run to get heat. Post back with more details. Then go outside and throw the disconnect switch, and see if the system still produces heat but the outside system doesn't work. If so, leave the disconnect off until you have the problem fixed.

With the disconnect on, disconnect the yellow wire from the thermostat at the furnace, and turn the furnace on. If you get heat and outside unit doesn't run, the problem is in the thermostat. If the outside unit still runs, chances are you have a bad relay. Unfortunately, you likely will have to replace the whole control board. $$$$$

I know more about dogs than much else. Society does a poor job of educating people about caring for pets. It also leaves many people completely unprepared for home and auto ownership. Fortunately we have AMHD and those willing to help others lower on the learning curve in almost any area.

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Originally Posted by labman

That seems unlikely. I hope I won't insult you by asking if what you have is a heat pump rather than a furnace. 2 ways to recognize a heat pump is the outside unit being up on legs, and you don't use gas or oil. The third thing is that the outside unit must run to get heat. Post back with more details. Then go outside and throw the disconnect switch, and see if the system still produces heat but the outside system doesn't work. If so, leave the disconnect off until you have the problem fixed.

With the disconnect on, disconnect the yellow wire from the thermostat at the furnace, and turn the furnace on. If you get heat and outside unit doesn't run, the problem is in the thermostat. If the outside unit still runs, chances are you have a bad relay. Unfortunately, you likely will have to replace the whole control board. $$$$$

I know more about dogs than much else. Society does a poor job of educating people about caring for pets. It also leaves many people completely unprepared for home and auto ownership. Fortunately we have AMHD and those willing to help others lower on the learning curve in almost any area.

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Thanks for your response. I took your suggestion and turned off the disconnect at a/c unit outdoors, which stops the a/c condenser fan outside. Actually, what I neglected to mention before, is that the furnace blower inside is also going on prematurely. If I understand it correctly, the plenum is supposed to reach a certain temperature, which triggers a switch, then the blower goes on. Right now the blower starts up before the plenum/heat activates the stop/limit switch. The problem w/the a/c unit may or may not be related, but I suspect it is. So, is the problem 1.) the relay, 2.) the stop/limit switch or 3.) something else. 4.) What I'd really like someone to tell me is, what is causing the blower fan to start up before the plenum heats up, and how do you fix it? By the way, this is a Furnace, NOT a Heat Pump.
Any help will be appreciated.
Thanks,
R

The blower is a bad sign. Newer furnaces use a timed delay rather than a limit switch. The circuit board may have gone haywire. That is a fairly easy fix if you can remove a bunch of wires and get them back on where they were. Trouble is, they are expensive, and difficult to make sure that is where the problem is. Does the furnace have a wiring diagram showing the blower controlled by a limit switch, or have you tracked it down?

Are you the original owner of the home? The reason I ask is that Whirpool P/C boards have a tendency to fail. Fan limit on the board is bad and easily removed and replaced. In fact I am going to a family members house in the morning for this very reason and wanted to check my first thought on diagnosing the situation. All possible answer to remedy you problem. Good luck, take care.

Im having problems with non cooling the airhandler has great pressures but it doesn't feel like it at all. Its like the heater and the condenser are both run even though they are on separate breakers