I think my AC may be broken.

[HoLeChit]

So Saturday night I noticed that my indoor temp was higher than usual before going to bed. I typically keep the house at 74-75ish during the day, and then once the sun sets we get the temp dropped down to 65 for bedtime until about 530 in the morning. The thermostat was telling me it was at 74 when it normally is down to about 68-70 by bedtime.

I didn’t think much of the temp, it’s been so hot that I just figured it’s struggling to keep up. But when I woke up in the morning on Sunday, it was 75 in the house. AC runs, sounds like the compressor is kicking on, fan is working, but it’s just blowing warm air. I last cleaned the unit this spring, and change out all the filters regularly. Cleaned it again yesterday, and checked the lines going into the house both the high pressure and low pressure lines felt lukewarm/ambient temp to me, which is odd, I could have sworn one is usually hot and one is cold.

I shut off the AC yesterday morning, thinking maybe something froze up. Im about to be turning it back on, and I worry that it wasn’t froze up, it’s just broken. It’s an older unit, manufactured in 1989. If it doesn’t come back on blowing cold air… any advice on troubleshooting? Suggestions on a HVAC company to come look at this in Edmond? Also, what’s a new unit costing these days? I’m not sure, but I think this is a 3 ton unit.

 

[Rez Exelon]

If you happen to have a capacitor you could swap in, that might be a good idea as a test. That's a 30 dollar test anyways unless you already have one. I might be an oddball but I always have spare caps for my units.

The other thing that comes to mind would be that you might have a refrigerant leak. Unless you had a FLIR camera or something, I'm not sure how to diagnose that one offhand.

We just had to replace one of our systems that looked just like yours because it was well past its end of life and making "angry" sounds when it was running shall we say.

 

[HoLeChit]

If you happen to have a capacitor you could swap in, that might be a good idea as a test. That's a 30 dollar test anyways unless you already have one. I might be an oddball but I always have spare caps for my units.

The other thing that comes to mind would be that you might have a refrigerant leak. Unless you had a FLIR camera or something, I'm not sure how to diagnose that one offhand.

We just had to replace one of our systems that looked just like yours because it was well past its end of life and making "angry" sounds when it was running shall we say.

I have a FLIR camera, but it’s more for electrical troubleshooting. What am I looking for with the leak? Cold?

Is this the capacitor on the top right? Or is it hiding somewhere inside the unit?

 

[HoLeChit]

Also, if anyone has pointers on finding the schematics for this, I would appreciate it. The schematics that were attached to the service cover are illegible.

 

[Aries]

It could be frozen up but it sounds like it's low on freon.

You are correct, one line should be colder and the other warmer. There *could* be a sight glass you can tell, but you need to know what to look for and otherwise you pretty much need gauges.

If it were a capacitor, I don't think your condenser would come on.

Schematics should be in the installation/operating manual if you have that somewhere. You can probably find them online, maybe manufacturers website?

DISCLAIMER: Not a professional by any means, but I do have some limited experience with refrigeration.

 

[ssgrock3]

I have a FLIR camera, but it’s more for electrical troubleshooting. What am I looking for with the leak? Cold?

Is this the capacitor on the top right? Or is it hiding somewhere inside the unit?View attachment 397587

Capacitor is the oil filter looking thing. That most often was our issue. After 15 years I blew seemingly once a year. But it is easy to fix. Always buy american capacitors (the Chinese don’t regulate theirs so no guarantee the oil inside is right or full.) I kept a few handy at our old home. Pull main ac breaker. Remove band that holds it, pay attention to which wire goes where..(take a picture) and replace. Sounds to me like the issue is the capacitor is not starting your unit.

You could also be a tad low on Freon,

 

[ssgrock3]

The blower will run the system just won’t cool. It is an easy check before you call an ac man

 

[HoLeChit]

Capacitor is the oil filter looking thing. That most often was our issue. After 15 years I blew seemingly once a year. But it is easy to fix. Always buy american capacitors (the Chinese don’t regulate theirs so no guarantee the oil inside is right or full.) I kept a few handy at our old home. Pull main ac breaker. Remove band that holds it, pay attention to which wire goes where..(take a picture) and replace. Sounds to me like the issue is the capacitor is not starting your unit.

You could also be a tad low on Freon,

Where can I find one? Just swing by Ace? Or is there somewhere specific I should go?

I should discharge said capacitor before handling it right?

 

[ssgrock3]

Where can I find one? Just swing by Ace? Or is there somewhere specific I should go?

I should discharge said capacitor before handling it right?

Locke supply should have it, Ace and the box stores might. I’ve never discharged one. Just disconnected and reconnected. I bought online and kept a couple handy after the first couple 100 degree day ac failures.

 

[ttown]

My first thought is Freon , if the motor is not spinning on your outside unit I’d suspect the capacitor. Your squirrel cage motor inside would be blowing hot air if your freon is low.

Doesnt sound like your compressor since you said you hear it engaging.

My .02 cents.

good luck