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Discussion Starter #1
I don't really know anything about the inner workings of my air conditioning, but I'm sure some of you do.

Lately my air has been blowing warm air when it's really hot outside. During the night and when I first start my car (and it's cool) the air works flawlessly, but it seems to "overheat" and completely stop working.

Any ideas? Maybe is it just low on some sort of coolant? In which case I could just bring it to a dealer for a cheap recharge I support. I'm hoping to avoid one of those super-expensive repairs/replacements.

Aaron
 
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Discussion Starter #3
Actually, it's an sr20. I posted in the general area because I'm sure the air conditioning units or the ga and sr operate in identical ways and this way I can be helped by the best and brightest from both trim levels =)

Aaron
 
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Discussion Starter #4
Your compressor fan may have gone out. I had to replace both my fans a year ago. They're electric and they go without much warning
 
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Would the air work at all if the compressor fan went?

Mine works fine unless I run it hard when it's real hot out.

Aaron
 
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Okay, I'm not gonna pretend to be an auto mechanic. I don't work on auto air conditioners. But I work on the cooling and heating systems in skyscrapers, so let's just say that I think I know what I'm talking about. The previous post about fans could be correct. Here's how you should go about checking the fan (and no, I'm not reading this out of a book. If you want the specifics, read your service manual):

Checking Condenser Fan Motor Operation

1. Start the car (duh)

2. There will be two fans behind the radiator: the radiator fan and the A/C condenser fan. Refer to your manual to determine which one is the condenser fan, or simply leave your A/C off while the engine warms up. Only the radiator fan will come on with the A/C off.

3. With the car warmed up, turn on your A/C. The A/C clutch will engage, you get the nice soothing hum of the compressor (yes, it's my trade; I love the sound of a good compressor as much as an auto mechanic loves the purr of a well tuned engine), and the fan should immediately come on. Unless your model has a head pressure controller that cuts the fan in and out; I live in Texas, it always hot, and that fan always runs on my SE. Regardless, the fan should come on PDQ as A/C head pressure builds. If it doesn't we need to troubleshoot why the fan isn't kicking on.

Troubleshooting Non-functional Condenser Fan Motors

1. First off, we need to check the fuse. You'll have to find it yourself. Good Luck! But seriously, if the fuse is blown, there are probably three causes: faulty wiring resulting in a short (check to make sure you have good connections; I had one go out because of a bad ground); burnt up motor (you can check the windings with an ohmmeter if you have one; this will be difficult if it is grounded to the motor frame; alternatively, take it to someplace like AutoZone and have them check it for you); or your motor could be overheating due to dirt building up inside the motor frame (I had this happen on a Ford; I dissabled the motor, blew it out with compressed air, and the motor outlasted two more compressors).

2. If you find that you need a new motor, be careful what you buy. I've noticed that D.C. motors for automobiles made by aftermarket manufacturers tend to suck, so I'd suggest buying the Nissan motor, unless it's just insanely overpriced. ALWAYS compare your old motor before buying a new one. The thing's gotta fit before it's of any use to you, right?
**make sure your motor is not overheating during the hottest part of the day, too. This is a problem I run into with my A.C. motors in outdoor installations**

Well, you've checked the condenser fan and, lo and behold, it's running just fine. Nuts. More than likely, you've got a refrigerant leak. Sucks to be you, my friend, because your best bet now is to take it to a mechanic. If you have an R-12 system: STOP! Unless you are licensed to work on it, you've got to take it to a mechanic. You'll be stuck with a hefty bill because he'll HAVE to retrofit the system to run a new refrigerant. I strongly suggest you have Freeze 12 installed (R-269B as I recall). I believe this R-12 replacement is authorized for cars *shrugs*. It's a heck of a lot better in 12 systems than R-134a because of the specific volume of the gases (don't ask). Don't be tempted to go to Wal*Mart and buy R-134a and gas your system up every week if you have a R-134a system. This isn't solving the problem of the leak, and it's a heck of an expensive band-aid fix. The leak can be found with a soapy water solution. But unless you have refrigerant recovery equipment and a high-vacuum pump, I highly suggest you take your car to a mechanic. It's the responsible thing to do by having your refrigerant evacuated before opening the system. Plus, you really need a good evac of your system to maintain it. If air and moisture are left in your system, they will form an acid that will eat out the seals, and will also eat up aluminum tubing, eventually leading to more leaks and failure of your A/C system. When you're looking for a good mechanic, there are a few things you should keep in mind. I've not met a lot of mechanics that are good A/C techs - no offense to any pro wrench turners out there, but I'm not impressed with the A/C skills of most mechanics; maybe the best thing to do is find a dealership with a designated auto A/C tech. If your system is flat, you need a new drier. No buts - this is not a debatable issue. It's job is to absorb moisture, and now it's useless because it's been exposed to atmosphere too long. Make sure one's installed. Yes, if you have a new refrigerant put in, he has to change the seals and the oil. Don't argue this: he's right. Do make sure he does the procedure properly, though. Ask if he triple evacuates the system before adding refrigerant. I'm not sure if this is standard for auto A/C's, but it is for all the equipment I work on. This means that the system is evacuated three times, removing all moisture from the system. Then again, that's why auto a/c's have those huge driers: because, like I said, most of these guys aren't that great at A/C, and they leave a lot of moisture in the system. As long as he evacuates the system once ( as opposed to purging with refrigerant to remove air, which is illegal), your system should be fine. I'm just a little anal about it because the equipment I work on costs anywhere from a hundred thousand to a million plus dollars. :-/

Well, these are the two most likely solutions to the problems described above. If you have any auto A/C questions, or any climate control questions (refrigeration, A/C, or heating) at all, feel free to contact me at [email protected] . Cheers mates.
 
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Discussion Starter #7
Thanks for the help - I'll give your ideas a shot and post here or email you if I need more help.

Aaron
 
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Discussion Starter #8
Leak

There could also be a leak in the AC system or it could just need charged......probably the latter of the two.....good luck.....mine did it and it was my compressor line that busted when i was doing a burnout at the track......DAMN WHEELHOP!!!!!
 
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By the way, Aaron, I'm sure your aware of this, but since your car's a '98, it has an HFC-134a system in it, so you won't have to worry about any retrofit. I wrote that reply in a general fashion for people that might have the same problem as well as you.
 
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Actually I wasn't aware - I haven't done much research into it yet and like I said in my original post, I know next to nothing about a/c units.

Thanks for the help =)

Aaron
 
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