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My A/C worked all of last year. I park the car over the winter. Took it out a few months ago when the weather was nice. When we had a hot day I thought no problem, flipped on the A/C and nothing but hot air. I know nothing about A/C units so I was just wondering where to start in diagnosing the problem?
 

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Start your engine, flip on the A/C switch to max in the car, then pop the hood and look at the a/c compressor pulley (bottom left in the belt chain). There should be a plate in front of the pulley, that's the clutch that engages the compressor when the system is commanded to do so. Watch it for a few moments, if it doesn't spin then your problem could be a bad clutch. Normal operation includes engaging for a few seconds immediately when you turn the a/c on, then it disengages once pressures are built. It will continue to cycle on and off as necessary to maintain the pressures in the system within spec.

If it does engage and disengage as I described above, the problem could be that you developed a leak and lost your refrigerant charge. Take it to a shop and ask them to test it for leaks; if they find something then you need to address those before recharging with refrigerant.
 

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If the A/C system has lost it's charge, through a leak, or even if the pressure is just too low, then I don't believe the compressor clucth will engage at all (I believe that's to prevent damage to the compressor).

Dennis
 

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My A/C worked all of last year. I park the car over the winter. Took it out a few months ago when the weather was nice. When we had a hot day I thought no problem, flipped on the A/C and nothing but hot air. I know nothing about A/C units so I was just wondering where to start in diagnosing the problem?
I don't suggest any system sealers either, that is my personal opinion and that of many pro techs.

Look around the system to see if you see any oil marks or stains near the spring lock couplings or on the compressor.

You can get a can of pure R134a, a charging hose with a meter and try to add some refrigerant to the system. Wear chemical eye protection and gloves, refrigerant will freeze you on contact.

Turn the dial to max AC. They will have to do this anyway to check for leaks, the oil has a dye in there. If the compressor cycles on on keep adding until the gauge gets into the normal range. The compressor should stay on for a few seconds then cycle, or if its very hot it will just stay on continuously. Rapid or no cycling is a low charge. A service manual can give you all the details, or you can do some searching on the web. Another trick is to charge until the vent temps are in the low 40s range on max ac.

If you want to do it right, you need a manifold gauge with 2 dials, and possibly a vacuum pump to draw a deep vacuum and put in the precise amount of charge.

But I've topped off systems and they worked for years. Again, avoid sealers no matter how tempting. There are places that wont touch a system that has sealers, because it hurts their recovery equipment.

Also, check your service ports for leaks after you charge...I've seen them bubble sometimes. They cost a few bucks to replace but you have to evac and recharge the system.
 

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I put a cheap $20 low side guage on mine and the pressure was correct. I jumped the low side switch on the receiver/drier to verify. $10 or less for a new switch.
 

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The pressure switch is a semi-common failure.

But like theterminator93 said the first step is to see what the system is doing before you just throw some freon in there.

Turn the system on and see if the compressor is running, if it isn't it is because of 3 common issues - no freon - bad pressure switch - or bad clutch on the compressor....the most common being a lack of freon.

The next step would be to get a pressure gauge to see if there is any freon left in the system. (many cans of freon will come with a cheap gauge now). If it is low on freon, CHECK FOR LEAKS, repair the leak then refill.

If there is plenty of freon in there, jump the pressure switch to see if the compressor comes on. If it comes on, replace your pressure switch.

If it still doesn't come on your clutch is bad or it's not getting power for some reason.

Hopefully that helps!
 

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Discussion Starter #7
Thanks for all the help! The clutch never engages, so I'm probably low on R134a or possibly the switch might of went out. Someone was telling me that I can't buy R134a here in Wisconsin. Does anyone know the facts on this?, or where I could find a recharge kit with a guage for a good price at?
 

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Since now you know your clutch isn't engaging, I'd get the system leak tested. You can do it yourself if you have a vacuum pump, but most shops should do it free/cheap. It'd be a waste to charge your system up with 134 only to have it leak out in a week or so.

As for Wisconsin law:

http://www.datcp.state.wi.us/trade/regulation/trade/refrigerants/index.jsp said:
Wisconsin law requires technicians to inspect for leaks and, if necessary, repair vehicle air conditioning and trailer refrigeration systems before adding refrigerant to these systems. The "topping off" of leaky systems is prohibited.

...

Refrigerant sales in Wisconsin are restricted to licensed businesses. This applies to all refrigerants including R-134a, the common replacement refrigerant used in motor vehicle air conditioning viewed as non-ozone depleting.
So I guess it looks like a leak test is required anyway. If your system doesn't leak and has a good charge, I'd check the connection at the clutch for power with the a/c on (use a multimeter). If you get power, chances are your clutch went south. Otherwise, like missycougar said, it's likely a bad pressure switch.
 

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I can't believe that some state actually has that much common sense to put that in writing.

I cringe when I hear people that paid someone to "top off" or "fill up" their system without fixing the leak first. I honestly am shocked when people think A/C systems use freon....I always respond with "when is the last time you added freon to your refrigerator or a brand new car....which then I get an "ohhh". I think it's a scam that some repair shops run....
 

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I can't believe that some state actually has that much common sense to put that in writing.

I cringe when I hear people that paid someone to "top off" or "fill up" their system without fixing the leak first. I honestly am shocked when people think A/C systems use freon....I always respond with "when is the last time you added freon to your refrigerator or a brand new car....which then I get an "ohhh". I think it's a scam that some repair shops run....
Well, I understand it a bit. First, I think people call it Freon much like people used to call copies "Xerox's." Xerox is a brand, but the word kind of stuck. Freon /= refrigerant, but people are used to calling it that. Why do we still call shocks, "shocks?" The technically correct term should be dampers, but everyone has been calling them shocks for so long that the name has stuck.

As far as the leak is concerned, I was under the impression that the leak testing dye was included in any A/C charge, so are they not one and the same (at least initially)? Now, to continually charge the system week after week get's pretty insane, however I don't blame the people who pay for a charge each summer... it's cost effective in the short term!
 

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If you are topping of your A/C because you know it's leaking and you expect it to go away again that's all good. However I feel sorry for the people that seem to think it's a maintenance item on an older car and don't honestly realize that have the option to fix it for the long term.

I'm pretty sure you can pick up a can of freon without any dyes or leak sealers, but you have to look closely as most of them come with one or the other (sometimes both).
 

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OK, you know the compressor clutch isn't engaging. First find the relay for the compressor and pull it out. You should have power at 2 of the terminals, ground at one only when the switch is turned on, and ground at the other through the compressor. If you don't have power at either of the 2 that should, check all your fuses. If you don't have constant ground on the one, check to make sure that the compressor is plugged in, and if it is either there is a break in one of the wires going to the compressor, or your compressor clutch might be fried. To find out which for sure, unplug the compressor and put power and ground directly to the terminals. If the compressor clutch engages, then it is a wiring problem. If it doesn't, you need to replace the compressor. If all the wiring and voltages check out, and you can get the compressor to engage by applying power and ground directly to it, then you probably have a leak in the system. Pull the cap off one of the service ports, and tap the valve real quick to see if it releases any refrigerant or if it is bone dry. If there is still refrigerant in it, grab a bottle of soapy water and start spraying all the lines, especially anywhere they join together, and when you spray the leak, it should form a soap bubble. If it is bone dry, grab a can of R134a and a charging hose from the auto parts store, and put some refrigerant in the system and then check for the leak.
 

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Just to add - you don't have to replace the compressor if your clutch ends up being bad. I was able to replace the clutch on mine in a couple hours without unbolting the compressor from the block - I just removed the high speed fan and coolant hose and pounded away at the old one until it came off. Also, I doubt you'll be able to buy a can of R134a off the shelf at a parts store, based on the laws and such. If you can find one, more power to ya'! But of course, get the system leak checked before you decide to charge it. This can be done easily with a vacuum pump and a good set of gauges.
 

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Also, I doubt you'll be able to buy a can of R134a off the shelf at a parts store, based on the laws and such. If you can find one, more power to ya'!
Do you mean R12? R134a is ALL over the place here in Missouri. Plus all cars switched to R134a in 94 if I remember right.
 

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Nah, I was assuming that based on the laws of Wisconsin (the whole "Refrigerant sales in Wisconsin are restricted to licensed businesses...") he might have to go to a shop that has a "license". I don't live there so I don't really know... but yeah, here in Ohio there are cans of 134 all over too.
 

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I find it hard to believe that he wouldn't be able to get R134a at a parts store, regardless of what laws the EPA in wisconsin has. Even if somehow he can't though, go on ebay and order up a can and have it shipped to you.
 

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I was interested so I checked out the wikipedia site R-134a

"A ban has been in place in Wisconsin since Oct 1994 under ATCP 136 prohibiting sales of container sizes holding less than 15 lbs of 1,1,1,2-Tetrafluoroethane, but this restriction applies only when the chemical is intended to be a refrigerant.[3]"

I also didn't know people were looking to replace R134A:

"In the EU, it will be banned as from 2011 in all new cars[1]. "

"SAE (International, an auto engineers association) has proposed tetrafluoroethane (HFC-134a) to be best replaced by a new fluorochemical refrigerant HFO-1234yf (CF3CF=CH2) in automobile air-conditioning systems[2]."
 

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Yea, you can't buy any refrigerant in WI without being licensed. I heard that was repealed back in 04 or so, but I guess that was just rumor.

You're not too far away from hopping over to MN and picking some up though.

I/We used to send people down to IL to buy it when I was in Milwaukee. 45 minute drive or so.
 

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Is the low pressure port where you add R134 on the accumulator with a black cap? This is on a 96 Cougar.

The only other port I found is in the line on top and has a red cap, that must be the high pressure side.

Thanks in advance,
Al
 

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The low side is on the accumulator near the firewall. The high side is on the liquid line near the condenser.
 
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