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A/C Not Workin'


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#1 subsince77

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Posted 26 March 2008 - 11:10 PM

Took the new motor on a road trip out of the snow and down to the desert. It was great to see real live dirt. It was actually warm enough to turn on the A/C. Unfortunately the A/C did nothing. It has always worked fine, as late as last November for sure. It has never been super cold, but always sufficient.

This time the compressor just didn't kick in at all. I checked the belt, it's fine, fuse is fine, unplugged and replugged the compressor, same with the four relays in the fuse box.

Two things have happened since I last used it. I got a new radiator, and of course a new engine. Done properly, neither should have messed with the A/C, but I would guess that done wrong either could have damaged a line or something. I can't see any obvious problems with any wires or lines, but that doesn't mean much.

Where should I start to figure out what's wrong? Should I have the refrigerant checked first, or look for an electrical problem? Can they just test the pressure in the system to see if it has freon. I've never had a problem with A/C before, so I'm in the dark here.

Thanks once again in advance.

#2 Jerry DeMoss

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Posted 26 March 2008 - 11:14 PM

I would start by checking the clutch on the ac pump and the electrical contacts.

#3 subsince77

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Posted 26 March 2008 - 11:18 PM

I would start by checking the clutch on the ac pump and the electrical contacts.

How would I check the clutch?

#4 screwbaru2

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Posted 26 March 2008 - 11:23 PM

One of the lines could have been streached a little too much during the engine work causing the coolant to leak out. When the coolant pressue is low the compressor won't come on. If this is the 97 we're talking here I'm pretty sure you have R134 not freon. The R134 is a lot cheaper. You can get it in parts stores like the old days. Most of the kits have cheap gauges in them to check the pressure. I think the pressures and type of coolant are on the A/C sticker on the radiator support bracket. Follow the directions in the kit you'll be fine.

#5 subsince77

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Posted 26 March 2008 - 11:26 PM

One of the lines could have been streached a little too much during the engine work causing the coolant to leak out. When the coolant pressue is low the compressor won't come on. If this is the 97 we're talking here I'm pretty sure you have R134 not freon. The R134 is a lot cheaper. You can get it in parts stores like the old days. Most of the kits have cheap gauges in them to check the pressure. I think the pressures and type of coolant are on the A/C sticker on the radiator support bracket. Follow the directions in the kit you'll be fine.


Sorry, I'm always behind on terminology, or rather materials. I need to check, but R134 is what I thought this thing used. It is a 97. If a line was "stretched" would the refrigerant just leak out again after I recharge it?

#6 aircraft engineer

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Posted 26 March 2008 - 11:27 PM

1 of 2 ways -

put power directly to the terminals (you bypass the clutch controls - if the system is "empty" you don't want to run it for very long or it will burn out the compressor) - you will also hear is distinct "CLICK!" when it engages and if you have the belt off, you can turn the pulley and the compressor clutch end will turn, too

alternate way, resistance test - test across the clutch terminals with the wires disconnected. (Don't know what "the right resistance" is, though)

oh, and R134 is "HCFC" - still a "freon" just with "hydrogen- chloro-fluro-carbon"

IF you have an empty system, you need to take out the "air" (with a vacuum pump) and then put in new R134 (autozone used to have the systems for "rent" - vac pump to evacuate the system plus the gauges to "check it")

#7 screwbaru2

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Posted 26 March 2008 - 11:32 PM

Yes, if it was streached enough to break the seal chances are it's not going to reseal itself. It's probaly just an O ring that needs to be replaced.

#8 screwbaru2

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Posted 27 March 2008 - 03:58 AM

1 of 2 ways -

put power directly to the terminals (you bypass the clutch controls - if the system is "empty" you don't want to run it for very long or it will burn out the compressor) - you will also hear is distinct "CLICK!" when it engages and if you have the belt off, you can turn the pulley and the compressor clutch end will turn, too

alternate way, resistance test - test across the clutch terminals with the wires disconnected. (Don't know what "the right resistance" is, though)

oh, and R134 is "HCFC" - still a "freon" just with "hydrogen- chloro-fluro-carbon"

IF you have an empty system, you need to take out the "air" (with a vacuum pump) and then put in new R134 (autozone used to have the systems for "rent" - vac pump to evacuate the system plus the gauges to "check it")


Around here if you ask for freon, you are asked to show a license to handle R12.

#9 Rooster2

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Posted 27 March 2008 - 05:48 AM

Around here if you ask for freon, you are asked to show a license to handle R12.



Yes, that is prolly correct. R-12 was always called freon. Prolly a slang term for its chemical ingredients. Every time that I bought R-12 back 10 to 15 years ago, I was asked to show my license. The store actually recorded my freon license number onto a reporting log. I had a license card from a diploma mill, that the stores accepted.

R-134 seems to be called only R-134, nothing else. No license needed to buy the product.

#10 subsince77

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Posted 27 March 2008 - 07:12 AM

One of the lines could have been streached a little too much during the engine work causing the coolant to leak out. When the coolant pressue is low the compressor won't come on. If this is the 97 we're talking here I'm pretty sure you have R134 not freon. The R134 is a lot cheaper. You can get it in parts stores like the old days. Most of the kits have cheap gauges in them to check the pressure. I think the pressures and type of coolant are on the A/C sticker on the radiator support bracket. Follow the directions in the kit you'll be fine.


I'll check into this today. Thanks. What about needing to vacuum pump the air out of the system first?

#11 aircraft engineer

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Posted 27 March 2008 - 10:45 AM

if you open it to replace the o-ring or whatever, you MUST (no choice) vacuum the system before refilling. (Trust me on this)

IF you don't it won't work "right" - the air will reduce the operation by probably 50% or more. It changes the "condensation" characteristics of the refrigerant so it might not "liquefy" in the condenser depending on how much "air" is in it

#12 subsince77

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Posted 27 March 2008 - 11:00 AM

I understand that if the system is opened, it has to be pumped. I just wondered about adding some refrigerant without pumping the air out first.

I went to a local mechanic this morning and we added some R134. Since it was low, I must have a leak. He used a can that he gets at Wal Mart because he is not set up to do much A/C work. He is however a friend that I can bother early in the morning and use whatever is in his shop. Anyway, this stuff has a "sealer" in it that he has actually seen some good results from I guess. So we topped it off for now, I'll see what happens. If it leaks back out quickly, I'll probably take it to Subaru in Grand Junction, or someone else in a warmer town. Funny, but we don't have a lot of A/C experts here in the ice box of central Colorado.

Thanks for all the info.

#13 aircraft engineer

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Posted 27 March 2008 - 11:39 AM

as long as you had "pressure" in the system it wasn't "open".

Of course, unless you stop the leak, you will just keep adding more 134 (well...duh)

The only reason to remove the existing 134 from the system is ... I can't think of any - you can just discharge it into the atmosphere.

(don't want to do that with 12 but unless you are a repair technician, I doubt that they will catch you anyway)

#14 Legacy777

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Posted 27 March 2008 - 12:04 PM

The only reason to remove the existing 134 from the system is ... I can't think of any - you can just discharge it into the atmosphere.

(don't want to do that with 12 but unless you are a repair technician, I doubt that they will catch you anyway)


Actually, you shouldn't discharge 134a into the atmosphere either. It's a greenhouse gas and is toxic.....but anyway...here's some info
http://www.eng-tips....d=156670&page=1

#15 Legacy777

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Posted 27 March 2008 - 12:06 PM

If you do open the system up, a strong vacuum (around -29 in/hg I believe) needs to be drawn for at least 30 minutes to boil off any moisture in the system.

If you don't have to open the system up, I'd also recommend adding some PAG oil to the system, as the oil may have leaked out over time, and if the system is low on oil, it could cause premature failue of the compressor.

#16 subsince77

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Posted 27 March 2008 - 12:54 PM

If you don't have to open the system up, I'd also recommend adding some PAG oil to the system, as the oil may have leaked out over time, and if the system is low on oil, it could cause premature failue of the compressor.


This bottle of 134 contained some kind of oil for the compressor, and R134, and the leak sealer - sounds suspicious, but that is why this guy likes it. Maybe it will work.

#17 aircraft engineer

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Posted 27 March 2008 - 01:07 PM

Well - toxic... er... no, it's not in the conventional sense.

it's a mighty powerful degreaser and displaces air so don't get any in a sealed room or it will suffocate you (tends to freeze skin too - but not NEARLY as much as the spray cans of "quik-freeze" that I have for testing electronics.)

But not toxic per se. NONE OF THEM ARE (unless you would be stupid enough to try to drink it - even at that it's STILL not "poisonous" but the "effects" wouldn't be pleasant - it's still a refrigerant)

Don't get it in a fire, though, because it WILL produce toxic gases when burnt (some fluorine-cyanide products IIRC)

The HCFC refrigerants aren't nearly as environmentally "sensitive" as straight CFCs. The "ozone depletion" potential is 100 or so X less. There are only a limited number of states that control HCFC releases. Since I CAN'T collect it, it has to go somewhere if the system gets opened (and system evacuation is sort of expensive - beats me WHY though - it supplies a potential source of re-usable refrigerant to the "collector")

#18 screwbaru2

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Posted 27 March 2008 - 01:35 PM

Subsince77, Ask your friend if he can get R134 dye for finding leaks. It used to be sold in R12 form years ago. You can track down any leaks then bring the car to a A/C service shop where they'll fix the leak, evacuate the system and recharge it. I do almost all of my own work but the A/C I leave to the guys with the equipment. I would advise you do the same. You can save money and protect yourself by knowing what is wrong before you have it serviced. They usually don't try to put the money pump on people who know what's going on. The oil in the refridgrant is there for the compressor, it's why the A/C should be run during the winter for awhile every month, to lube the compressor and keep the O rings lubed and soft.

#19 aircraft engineer

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Posted 27 March 2008 - 01:39 PM

Schucks (Checker) whatever they are called - usually have it

Show (purple? might be red?) at the site of the leak. beats the old fashioned way with the flame leak detector

#20 subsince77

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Posted 27 March 2008 - 08:59 PM

Subsince77, Ask your friend if he can get R134 dye for finding leaks. It used to be sold in R12 form years ago. You can track down any leaks then bring the car to a A/C service shop where they'll fix the leak, evacuate the system and recharge it. I do almost all of my own work but the A/C I leave to the guys with the equipment. I would advise you do the same. You can save money and protect yourself by knowing what is wrong before you have it serviced. They usually don't try to put the money pump on people who know what's going on. The oil in the refridgrant is there for the compressor, it's why the A/C should be run during the winter for awhile every month, to lube the compressor and keep the O rings lubed and soft.

Yes, this is what I was going to look for next, but I wasn't sure if you could get this dyed stuff any more, at least in a form I can use.

My thoughts exactly on taking it to someone - I'm not going to take anything apart on this thing. I now know that the problem was not an electrical one, or really a mechanical one in the sense of a bad clutch or compressor or something. I have a leak. If the sealant actually works, then the pressure should stay the same. If not, I want to find where the leak is THEN take it to someone to work on only those areas.

We will be in Albuquerque next week, so I can look for some R134 with dye there. It's a good A/C town. Our stores won't even stock it for another 2 months. My buddy just happened to have a can on the shelf, so we used part of it.

#21 Legacy777

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Posted 28 March 2008 - 11:47 AM

Yeah, you should be able to find uv dye for the ac system in a can.




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