AC Keeps Shutting Off (Photos)

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1984CuttySupreme

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Apr 26, 2010
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Altamonte Springs, FL
The AC in my cutlass has been an issue for a while. We replaced the compressor, blower motor, etc, etc. but I keep having issues with it not working ever so often. Usually when it cuts off I check the "AC" 25 Watt fuse and the fuse is melted but not severed. So today I replaced the fuse and it worked for a couple minutes and shut off again. The fuse looks fine but the AC will not come on at all anymore. We've replaced the relay switch on the dash a few times and it will work for a while then start having the same problem. Here's some photos, it's a bit of a mess. We put in a rebuilt motor with an Edelbrock carb so all the electronics are disconnected and just laying around. Any ideas what would cause this?

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Bonnewagon

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What is your low side pressure? It will cut off under 25psi. See the low pressure valve in the second picture? If you jump the wiring it will make the compressor come on if all else is working right. Otherwise it's probably a short from a bruised wire blowing the fuse.
 

1984CuttySupreme

Not-quite-so-new-guy
Apr 26, 2010
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Altamonte Springs, FL
Bonnewagon said:
What is your low side pressure? It will cut off under 25psi. See the low pressure valve in the second picture? If you jump the wiring it will make the compressor come on if all else is working right. Otherwise it's probably a short from a bruised wire blowing the fuse.

Should I check the wiring behind the fusebox? We've replaced the relay switch & all that on the dash so I don't think it would be in that area. For the past 2 days I turn the AC on and nothing happens, then today I decide to try it again and it turns on. It worked for a couple 10 minute drives and then it started acting up. The blower speed would decrease as I press the accelerator and the charge light would come on. Then the car wouldn't crank up after that.
 

Bonnewagon

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Sounds like the AC is just a symptom of a much larger problem. Time to break out the multi-meter or test light and start hunting a major short.
 

1984CuttySupreme

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Apr 26, 2010
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Altamonte Springs, FL
Bonnewagon said:
Sounds like the AC is just a symptom of a much larger problem. Time to break out the multi-meter or test light and start hunting a major short.

This is gonna sound extremely noobish but which multi-meter do you recommend buying and how do I start checking for shorts? I've never used one before. Or is this something I should take somewhere to have checked since I pretty much have to clue where to begin lol.
 

Bonnewagon

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A good one runs $$$$ but you can get one from Harbor Freight for under $10. You can also get a simple test light for like $5 that is great for testing 12 volt systems. Do you have a factory manual or Haynes, something with wiring diagrams? Even a generic auto electric book from a speed shop will get you started. You might as well learn about car wiring if you plan on doing any serious work. Electrical problems cost big buck$ for a shop to diagnose. Just start simple like the battery and it's hot-all-the-time red wires, the fuses, grounds, and simple circuits like lights.
 

jrm81bu

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Jul 9, 2008
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I repied in your other post but I will repeat here. First thing to do is get your alternator tested. It doesn't matter if it's kinda new or not. Don't rule it out because of that. My reason for this is beacause it sounds like after you charge it overnite it (the car) runs okay for a bit then acts up and either dies or after you shut it down, won't restart. Like you said here
For the past 2 days I turn the AC on and nothing happens, then today I decide to try it again and it turns on. It worked for a couple 10 minute drives and then it started acting up. The blower speed would decrease as I press the accelerator and the charge light would come on. Then the car wouldn't crank up after that.

The reason the blower speed is decreasing when you give it gas is because everything is running of the battery(which is going dead) and can't support the blower fan and power to the coil at the same time. And then when you shut it off the battery is far enough dead that it won't start. Until you re-charge it right?
You don't want to keep running the battery dead because eventually you will ruin it.
Have you ran it long enough to just have it die on you?
And since you say it lasted two days, I'm gonna guess that most if not all of that driving is during the day?
It seems that most of your problems could be attributed to the alternator not working and the battery slowly going dead as you drive.
 

1984CuttySupreme

Not-quite-so-new-guy
Apr 26, 2010
34
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Altamonte Springs, FL
Yea I havn't driven it at night at all. The closest I've gotten to the battery dying while the car was running was today during the AC issue. I turned the car off and attempted to crank it right after and nothing. I suspected the alternator as well but I replaced it a few months before we did the engine swap so I just assumed it should be fine. And a mechanic did a light meter test on it yesterday morning and he said the alternator is fine, although I'm not sure you can tell by just that.
 

jrm81bu

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Jul 9, 2008
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The light won't tell you anything accept that there is enough voltage to run a light, lol. Get it tested and don't just look at the volts it's running, find out how many amps it is pushing as well. If you have an Autozone or Advance auto near you, drive the car there and have them test it on the car(looking at both numbers). If it don't check out, take it off and have them test it again on the bench. If it's bad then replace it, if it's good then you know you have a problem with the car. The alternator may not be getting excited on the car.
 
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