air conditioner no workie

[Warren Lake]

do I need that, is it not that the capacitor is gone and that is why the contactor is not getting power? sorry I dont understand more wish you were close by id hire you to look at one machine I need running right away and it was after i had taken some start buttons apart past.

[Warren Lake]

just adding to my post that doesnt show I had taken the two start buttons apart and got both working fine machine left for a while then Murphy must have settled in need to look at it in case im missing something.

[Brice Rogers]

I've been nursing two AC units for over 25 years. The failures that I have incurred include:
1. AC capacitor (probably 3 replacements - - major failure item). They typically get "puffy" when they fail. They cost about $20 or less. You can check them with an ohm meter do determine if they are "open", or "shorted" (unlikely failure mode). Let me know if you want to know how to determine if they have capacitance - - or just spend $20 and replace it.
2. Cartridge fuse (they are only good for a certain number of cycles, so they can fail). They are located inside the disconnect. It is easy to ohm them to determine if they have opened.
3. Contactor contacts had a fried bug in them. 800 grit sand paper fixed it. People told me that I shortened it's life (10 or 15 years ago).

[Tom M King]

If that capacitor is blown, nothing will run, or as they say around here: "she won't say nuthin' "

I learned how to work on them myself, and have all ours running great, but I didn't figure it out in my head without some studying.

There is a long list of possible problems, but it's so easy to check the cap that's usually the first place the troubleshooting stream starts.

[Rod Sheridan]

Hi Warren, with the thermostat calling for cooling, measure the contactor coil voltage, it should be 24 volts AC. There probably isn’t any due to a safety interlock

My suspicion is that the low pressure switch has opened due to a leak, or the high pressure switch has opened. The high pressures switch may have a reset button, if so press it once.

Probably time for an HVAC tech, in Ontario you need a license to work on the refrigerant circuit.

Regards, Rod

[Bill George]

Having been in the HVAC business for 30 years or so I may add a little advice. If the outside contactor is not pulling in its because it does not have the 24 volts or it does and the coil is burnt out. The bugs have been mentioned and that is certainly is possible turn off the 230 volts and check. I had one that routinely bugs would chose to get smashed.

The compressor starts and runs you proved that by pushing in the contactor which rules out the compressor capacitor and the bugs.... maybe. If its a higher dollar unit it might have a high or low pressure limit switch that tripped.

You need a voltmeter to check for 24 volts AC on the coil, if you have it, then the contactor needs replaced. No 24 volts, either a wiring issue, limit switch or the thermostat Y wire.

When troubleshooting you always start with the thermostat, turned to Cool does the blower or furnace motor start? Did the outside unit fan start, you have just proved you have power to the blower motor and the thermostat works. Outside fan on, you have proved you have 230 volts, not cooling start from there.

[Warren Lake]

in the house when I turn the thermostat down after some seconds there is a clic. That would be normal and from inside id hear the unit start. This time after the clic the unit does not start. So I hear that signal from the thermostat clic and the furnace makes that pause for a split second, past id always here the unit turn on its close enough just outside. Had an AC guy a block away he moved. have to pick up materials so it wont get more attention right away.

[Rich Engelhardt]

A/C no workie = call a guy and get ready for the really bad news.
Bad news is you need a new A/C.
Really bad news is you need a new furnace too.

Really terrible news is while they are replacing the furnace, they tell you the water heater is on it's last leg.

Been there - had all of it happen. A/C and new furnace multiple times.

[Tom M King]

Here is one of my favorite HVAC youtube channels:

https://www.youtube.com/watch?v=5UU2c5e2ork

[Tom M King]

This is the other in the top two channels:

https://www.youtube.com/watch?v=1nQ7k_X2aXA&t=556s

[Warren Lake]

see what the coil thing is, notice the wires that go to the contactor are really long pull them out notice the slip on connectors are loose on both and the tangs whatever they called are sort of dull corroded. would make sense to clean them with some fine sandpaper first id say. Not sure why such long wire length but guess it doesn't matter maybe not the contacts but worth looking at

So that wire from my thermostat should show 24 volts? there are two so same on a battery there is a positive and a negative or one is the ground. Am I concerned with that or just hook the mulitmeter up to either then reverse if not reading to be sure im not back wards?

thanks

[Michael Weber]

Warren, it doesn’t matter which meter lead goes to which wire on the contactor.

[Bill George]

see what the coil thing is, notice the wires that go to the contactor are really long pull them out notice the slip on connectors are loose on both and the tangs whatever they called are sort of dull corroded. would make sense to clean them with some fine sandpaper first id say. Not sure why such long wire length but guess it doesn't matter maybe not the contacts but worth looking at

So that wire from my thermostat should show 24 volts? there are two so same on a battery there is a positive and a negative or one is the ground. Am I concerned with that or just hook the mulitmeter up to either then reverse if not reading to be sure im not back wards?

thanks

Its AC alternating current has no polarity. And remember the KISS rule and start with simple.

[Warren Lake]

thanks ill try and clean and measure before I go pick up materials if not will be when back apprciate the info Yes its time for new stuff but at the moment prefer to get this running if possible. Takes me a bit of time to do research on stuff with most things. Furnace a 90,000 Keeprite super high effic and know its time so both get done same time could use a few more months to keep focused on other stuff.

[Warren Lake]

I got sort of different readings wish the meter had clip on ends, will get some. The readings I got were mostly 2-3 volts. Did at one point see 10 but for the most sort of 2-3 and that is pressing the wires hard on the meter ends. Is the multimeter set correctly think so this is where id read a car battery and see about 13 volts approx. realize the 24 you are saying is more than the 20 setting on the meter. when I got 2 3 it was almost if I waited or that it came up a few times to six or the one time for 10 but for the most part just low as shown or bit more these are the wires right at the AC unit that come from the thermostat in the home

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