41 posts, read 438,775 times 1,009 posts, read 3,064,328 times A defective contactor is one candidate. YouTube - Residential HVAC Contactors Part One Originally Posted by cgar22 Your queries reflect that you are NOT taking the initiative to do Google and YouTube research. Pretty much 2 types of internet users . The latter tend to seek out others to exploit with endless questions. 3,537 posts, read 10,227,433 times the fan should run when the unit is running , right ? 276 posts, read 746,924 times 7,475 posts, read 16,253,628 times 9,123 posts, read 34,300,328 times Originally Posted by Hoot Owl Is the house actually reaching the set temp? You could be low on refrigerant? If not, it could be the relay switch @ the compressor. Condenser units are notorious for collecting leaves and other debris and some of it could be effecting the switch and/or the condenser itself- not allowing for enough heat molecule transfer. Or it could be the T/stat itself, as mentioned before.

605 posts, read 3,859,011 times 14,070 posts, read 39,900,025 times 3,785 posts, read 15,674,846 times 3,191 posts, read 6,970,571 times Originally Posted by crazyma It's the inside blower in the closet (attached to the furnace) that's acting up. Not sure which brand it is. Tell your husband that the fan is now turning on and off with the compressor - like it should be doing. Not sure why, for a day, it ran constantly.Look forward to your reply. 82 posts, read 438,721 timesIt only happens occasionally. indoor blower goes off; outdoor unit continues to run and can only be turned off with circuit breaker. Only 2 or 3 things can cause this. The most common is a stuck compressor contactor. Located in the outside unit, the contacts get pitted and eventually weld shut. This can cause serious damage. Some authorities think it is good practice to replace the contactor every few years just like you would replace the spark plugs in an automobile. Other causes would be a shorted thermostat cable or a defective thermostat.

Below is a list of possible causes and usually require a service technician to correct. The company You Choose To Install and Service Your System Will Determine The Degree of Comfort and Satisfaction You Enjoy. hvac unit for saleExcerpts of the preceding information have been compiled by Hannabery HVAC, which has graciously permitted us to include them on this web site as a service for all homeowners.install through wall ac unit Heating Ventilating and Air Conditioninghotel heater and ac unit What would cause the outside air conditioner fan to stay on constantly when the inside unit is turned off? What would you like to do? There are two reasons for the outdoor fan to remain on while the system in side is off . The first is that the contactor on the outside condensing unit is frozen closed.

In this case the 240 volts supply to fan and compressor will not be turned of when the inside system goes off. If both outside fan and compressor remain running for a time then the system will freeze up and ice will form. The second is that 24 volts is still be supplied to the outside contactor even though the thermostat is satisfied. The 24 volts would be supplied by an electrical short between the red and the yellow wires . The short could happen any where along the thermostat wiring where the two bares have become bare and are touching.How would you describe your personal style in 3 words? What would cause a central air conditioner to make a dripping sound in the inside unit and leak water? What would cause the outside part of your air conditioner to frost over? Air conditioner condenser fan constantly cycles on and off? Why would the air conditioner in your car stay on after you have turned the ac off? What causes water under your car when the air conditioner is turned off?

What would cause an air conditioner compressor to go off and on? Why is air conditioner running outside unit but not blowing inside? Split unit air conditioner outside unit not running. Inside comes on - air blows not cold - outside unit buzzes? Why does house ac unit compressor run constantly and unit fan but no cool air blowing inside house? What causes a home air conditioning unit to not turn off? Outside air conditioner fan freezes up? What could be wrong if the fan on outside air conditioner unit is not running but there is air blowing out the vents? Air conditioner doesn't turn off? Why would blower motor of air conditioner stay on in 1999 Chevrolet Express van when engine is turned off? Ac fan on the inside is not running but outside unit fan is on? What is wrong if your air conditioner fan on 1996 Chrysler Sebring never turns off? Heating AC and Engine Cooling What reasons would cause your home air conditioner unit to cut off?

Before I begin, I would like to request "call a technician" suggestions to stay off. I do know a nice guy who can look it up for me, for a variety or reasons, one of which being my general history of fixing stuff, I would like to take a first stab at solving this problem. Background: Both units are middle-of-the-line Lennox, about 2 years old. The thermostat is Nest 1st generation, which also controls the completely separate hydronic heating system used with radiators. The system does only AC (is not a heat pump, in other words). Problem: I turn the AC cooling on and only the indoor unit (air handler) fan comes on. The outdoor unit (compressor) stays off. I checked power supply at the main panel (both units have a dedicated circuit, 15A for the handler, 30A for the condenser) and using a pen-like current detector. 1. Inside Air Handler Note that the upper thermostat cable is what goes to the compressor, lower goes to the thermostat. The two white wires are from a small water detector attached to the pan in which the return box sits to switch the system off in case water drips in the pan.

Note that the RH red wire and the W1 white wire come from the above mentioned radiator heating system and are completely unrelated to this. RC red goes to the R in the air handler. So the C connector from the thermostat is connected to the air handler via the blue wire, which goes to C in the air handler and to which the blue from the compressor cable connects it to the black wire in the compressor. My suspicion is that somewhere along is the problem unless the compressor is broken, for example a problem with its capacitor or something else broken. Question: How can I diagnose where the problem is using a multimeter? Is it possible to narrow the problem down to the capacitor OR the thermostat using my analog multimeter, i.e. to rule out the wiring, which seems like it is fine? I can turn the system on and I would like to use the multimeter to verify that the thermostat is properly turning the cooling on via the blue wire to the compressor. If so is the case, then the wiring is not the problem.

The first thing to do is check the two wires on the outside unit when the thermostat is calling for cooling. In your picture it looks like the Blue and Yellow thermostat wires are being used. You should have 24v AC across those two wires, which would normally close the 240v relay and start up the compressor and cooling fan. If you're not getting 24v on the two thermostat wires, there's probably a bad connection somewhere. Since the air handler is working and the thermostat has power, the 24v transformer is working. If you are getting 24v, then you can move on to diagnosing just the compressor. There are limit switches that can prevent the compressor from turning on if the coolant level is off. There can also be temperature sensors that prevent the compressor from running, so these would need to be checked. The relay should also snap shut when the 24v signal is present. A poor connection might read 24v, but might not have the amperage to actually close the relay. The relay can be corroded or filled with dead ant bodies.

I hope this helps. Clarify anything you can in the comments and I can attempt to edit as needed. I've done a lot to diagnose and solve problems with a WiFi thermostat and heat pump that were not wired correctly. The compressor is in the condenser unit where the heat is removed in most cases. The evaporator is inside the air handler where the cold air is made for the house. If the cap is blown it will still try to start and normally blow the fuse. The cap can be checked out of circuit by using ohms and touching the leads you should see the value climb. Then reverse the leads and you should observe the same thing. It looks like you may have a dual cap look on the label to make sure then there would be 2 combinations to see the charge on the ohm meter. There is usually a contactor or relay that is controlled by the main unit or thermostat. If this contactor is not pulling in the power to the compressor and fan are not turned on to the compressor and fan motor. I had the same problem many years ago.