Ok... very new to this. I have a Trane XE 1000 and just went to turn the air conditioning on and I figured everything was fine, it sounded as if it started up OK. Went to work and when I came home the house was very hot and the vent was blowing out warm air. Checked the fuses in basement and everything seemed fine, so I called my dad and he came down and said the outside unit was not on. Unfortunately, I am recently single mom and my dad did not know what to do. Any suggestions about what could be wrong? There are fuses on the outside unit on the house, but I have no clue if they need changed or anything. Has worked fine every year that I have lived here which is 11 years and I have never changed fuses or anything.

Please help female in distress about air conditioning.

If you no nothing about electricity you can get hurt bad from just trying to replace a fuse. If the system is not running it may be line voltage(240v) or low voltage(24V). Its hard to say. If you or your dad knows how to use a volt meter we may be able to walk you through it.

My dad used a volt meter yesterday, but he said everything seemed fine... Of course not sure what he meant by that. He opened a box on the house and said something about fuses but otherwise was not much help. I am just afraid that I am going to have to call repairman, which I can't really afford right now.

How do you start a new thread on this site? Anyway, I'll have to post it here then...
I have a Trane xe 1000 outside AC unit that's not working and doesn't make a sound. I checked power to it and I'm getting 240 at the unit... So I replaced the Contactor and Capacitor and still nothing the fan turns freely too, so not blocked. I have more tests to do on it but It's raining out so I do them later just running this by you all to see if I can get some insight... Probable problems/questions... The whole AC unit is quiet... No hum from motor no sounds from compressor and worked fine last summer... Thermostat is a Hunter digital not the original and about 7 years old... I can turn on the heater with it but not AC... red blinking light on XE90 flashes about once per second, but writing on the control panel says that that's normal operation "No call for heat"... So I'm thinking there's nothing telling the AC unit to turn on after we turn on the Tstat so it might be bad... cheaper fix then having to call out a service tech.
Does this make sense?
Thanks in advance for your help

When you activate the t-stat for a demand for cooling do you have 24v at the side of the contactor (the coil)? Is the plunger pulling in or after a demand for cooling? Or is there 0 volts at the contactor coil?

when you checked the 240 at the unit did you check the line side of the contactor like in this video:


It is around the 30 second mark

you can also rule out low voltage issues with this video test here at the contactor:

Quote:

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Originally Posted by thermalmedics

when you activate the t-stat for a demand for cooling do you have 24v at the side of the contactor (the coil)? is the plunger pulling in or after a demand for cooling? or is there 0 volts at the contactor coil?

when you checked the 240 at the unit did you check the line side of the contactor like in this video:


it is around the 30 second mark

you can also rule out low voltage issues with this video test here at the contactor:

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Thanks for your quick answer and the video links... The Trane XE 1000 insides are a lot different then the ones in the videos. It just has the fan motor, condenser, contractor and capacitor and wires. The power comes right off the breaker inside the house with a separate 12aug wire coming from the Tstat that goes to the furnace then to the AC unit. Yes I tested voltage at the unit by removing wire nuts on the wire coming from the breaker 240v... The system is about 17 years old so I just changed out the contractor and capacitor and the new contractor doesn't have the push switch on it like the old one did. Still raining so I can't check anything more today, I think I'm going to test the contractor voltage first and if need be put the old contractor back on and test the push switch before I do anything else.
Thanks again I'll keep you posted

Is there a small cover over the new contactor you can remove to get to the plunger. Many of the new ones have a 'safety cover' that has some small screws.

Yea I would definaely do the test at the contactor first if and/when you find it. That will tell you which path to head down. Low voltage (from t-stat) or hi (capacitors, wires, compressors etc.. )

Update: I removed the contactor cover and pushed the plunger and the unit came on. AC unit does work but still doesn't come on when turned on at the thermostat. So I tested the wire coming from the furnace/indoor unit to the AC... No bad or broken connection. I tried to jump the yellow wire to the red on the thermostat, No luck so I have another manual thermostat so I switched it out with the digital one. No dice, AC still doesn't come on.
The 4 wire thermostat wire goes to the furnace which connects to the White-Rogers control unit in the furnace and connects with the 2 wire (the one I checked) that goes to the AC unit.
Question: What controls/tells the AC unit to turn on if not the Thermostat, is there something I'm missing?

Check to see if you have 24v from the thermostat wire going in to the A/C unit If so Check for 24v at the contactor. If you have 24v going to the unit but not at the contactor you have a open limit or pressure switch.

Do you mean the 2 wires on the side posts of the contactor? I forgot to add that I did check them and there was no voltage present, But I didn't have the thermostat turn on at the time. Does it have to be on or is there always 24v present and would that still be the pressure switch?
Also doesn't the open limit or pressure switch have to do with heat? My heater and the air handler/blower work fine. I did check currant at the thermostat, using my meter getting 28v checking green to red, and yellow to red. Yellow to white and or green to yellow and white no readings. Is that normal?

The low voltage wires should be on each side of the contactor down low. Some systems will have a low pressure switch that will open if refrigerant is low or lost. The high pressure switch will open if the pressures get to high, compressors will have a high temp limit on top that will open if all the previous limits fail. All are in place to keep from doing damage to the compressor.

Quote:

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Originally Posted by T-Top

Check to see if you have 24v from the thermostat wire going in to the A/C unit If so Check for 24v at the contactor. If you have 24v going to the unit but not at the contactor you have a open limit or pressure switch.

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Thanks for your help T-Top.
The weathers been nice here for a while so I haven't had a need to check the AC.
Ok, I have one question about the pressure switch. When I put my meter to it should I be getting any voltage and what kind of ohms reading will there be? Everything tells me this switch is bad but I just want to know for future reference.
Here's a picture of it...
Thanks again for all your help.

Ok fixed the problem, I did some further meter checking and found the 2 lead wire going from the furnace to the AC unit had a break in it. Unit works and all is well.
Thanks for all your help