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AC does not cool enough - Compressor does not cycle and the fans stay on
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mmm2000
New User
Feb 24, 2014, 7:40 PM
Post #1 of 11
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AC does not cool enough - Compressor does not cycle and the fans stay on
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Year of vehicle 2000
Make of vehicle Nissan
Model of vehicle Sentra
Engine size 1.8
Mileage/Kilometers 120,000
AT
Manual AC controls
Facts:
- When I turn the AC on, the compressor kicks in
- the clutch stays engaged at all time, does not cycle off, ever. If I turn the AC off, the compressor clutch stops from spinning.
- The 2 radiator fans stay on all the time if AC is on, and they turn off if I turn AC off.
- The air that is supposed to be very cold, is just barely cold. I say I get about 15-20% performance out of my AC system. Still cools a bit.
- I connect a gauge to the low side and the pressure with the engine off was in the "normal" level. This was an AC gauge from an auto parts store.
- The AC worked fine, just a few months ago, then I stopped using it because of the winter, for about 2 months or so. When i turned it back on, recently, it experienced all the above.
- The heater works fine.
- These conditions happen while outside the temperature is about 65-70 degrees.
I have the factory manual for the car, but I do not know where to begin diagnosing my car. Please help!
(This post was edited by mmm2000 on Feb 24, 2014, 7:42 PM)
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Hammer Time
Ultimate Carjunky
/ Moderator
Feb 24, 2014, 7:43 PM
Post #2 of 11
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Re: AC does not cool enough - Compressor does not cycle and the fans stay on
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The first step is to have the system evacuated and recharged with the correct weight of refrigerant. This is not something that you can do yourself.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Hammer Time
Ultimate Carjunky
/ Moderator
Feb 24, 2014, 7:48 PM
Post #4 of 11
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Re: AC does not cool enough - Compressor does not cycle and the fans stay on
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The only way to find out is to evacuate and recharge the system. That toy gauge that you are using cannot tell you anything about the system and the actual pressures don't mean a thing until you know exactly how much refrigerant is in the system.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Sidom
Veteran
/ Moderator
Feb 24, 2014, 9:14 PM
Post #5 of 11
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Re: AC does not cool enough - Compressor does not cycle and the fans stay on
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There really isn't much diagnosing a DIYer can do on an a/c system without the proper tools......The 1st step on a problem like this would be recover the refridergant to see how much was in there and then recharge the system with the proper amount and see how it works......If its working properly, then there is a leak than needs to be found and fixed& if not, then there is a component that has failed and you will need pressure & temp reading to find.....
Usually DIYer will recharge the system themselves and if that doesn't work, take it into a shop......One bit of advise I can give you, if you decide to roll the dice and try this yourself....Just get straight 134.....Don't get the stuff with stop leak or any of those other additives.....Stop leak can destroy your system when it mixes with the oil in it.....
The best advise is to take it into a shop.......but if you are going to try this yourself (against a techs advise) then just use straight 134 and realize that it is very easy to overcharge a system and hurt yourself........Last season I had a Honda that holds less that 2 lbs of 134 with a bad expansion valve that the customer was able to get 5 lbs in before he ran out of money & patiences......He's really lucky he didn't hurt himself or his car..
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mmm2000
New User
Feb 24, 2014, 10:01 PM
Post #6 of 11
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Re: AC does not cool enough - Compressor does not cycle and the fans stay on
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After further inspection, I noticed something that looks like a very small leak on the discharge line that connects the compressor and the condenser. There is nothing else that is moist in that area except that AC hose. Should I inject some AC dye in the system, just to make sure that is the leak and also inspect all the AC hoses for additional possible leaks with the UV light, before taking the car a shop to have the hose replaced and the AC system recharged?
(This post was edited by mmm2000 on Feb 24, 2014, 10:14 PM)
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Feb 25, 2014, 1:55 AM
Post #7 of 11
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Re: AC does not cool enough - Compressor does not cycle and the fans stay on
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A leak is the most common reason for A/C to fail but also can cause other problems so would be nice to know now if the system can work properly with a proper charge which is by exact (EXACT) weight and this car appears to hold just 18oz (charts can be wrong so go by any info under the hood first.
Small capacity systems off by 10% are going to show performance changes and much more troubles so most can't charge to that close tolerance.
OK: However you think you know where a leak is what did you see to think that? If clearly a leak it should be oily and apparent that the oil isn't from something else. It's possible it would show itself with plain soapy water however if it did it would soon be too low to do anything real soon.
Plenty to know and understand just to charge a known working but empty system and the equipment to do so. No dipstick for how much is in it now just the symptoms that it isn't correct. Your static pressure only means it has some not how much BUT if just that is roughly lower than the ambient temp in F. it's considered empty.
Read just what it takes to charge a fixed or known working system from an info thread locked at this site and decide if you can follow all that to every detail and have the equipment to do that. Just know doing it wrong is harmful and dangerous. You can also take a small problem and make it a disaster so beware.
This is a good read from this site and suggest you decide to get serious about DIYing or send it out.
Click this for the read...... http://autoforums.carjunky.com/..._A/C_SYSTEMS_P45460/
Decide from there is my suggestion,
T
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Discretesignals
Ultimate Carjunky
/ Moderator
Feb 25, 2014, 5:50 AM
Post #8 of 11
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Re: AC does not cool enough - Compressor does not cycle and the fans stay on
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You shouldn't dye it unless you evac and recharge it to the correct weight. You really don't want to run it if it has a low charge. You'll just burn up the compressor from lack of oil. You should have a repair shop that specializes in ac repair charge it back up for you and add a dye. Then you can drive it around and figure out where the leaks are.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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mmm2000
New User
Feb 26, 2014, 9:29 PM
Post #9 of 11
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Re: AC does not cool enough - Compressor does not cycle and the fans stay on
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I did not run the AC at all lately. First pressure test I have done on the low side was with engine off. Big mistake, because I did the same test with the engine running and the pressure drops to pretty much zero with AC running.
My engine is dry 100% and also all the other components. No leaks or oily residue anywhere except on this AC discharge line. So I ordered the part online $55 compared to 120 at the dealer. Part arrives on Monday and I will take it to a shop to have it replaced and recharge my system. Recharging $120 plus the hose another $50. My system takes 1.1Lbs.
Thank you all for the advice.
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Tom Greenleaf
Ultimate Carjunky
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Feb 26, 2014, 10:44 PM
Post #10 of 11
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Re: AC does not cool enough - Compressor does not cycle and the fans stay on
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? So you did find evidence of a leak on discharge line? If so it's slow as system still engages at all vs empty would quit. Hope the recharge will show it isn't damaged.
Just FYI - Refrigerant is just a condensable gas meaning under reasonable pressures at reasonable temps it can be a liquid or gas and the magic of change of state can be captured. When you took pressure with everything off you merely found out it had SOME refrigerant in there and with that you know the temperature and vs versa. Chart shows just what pressure you have at what temps no matter which you know you can know the other.......
You see that at ~70F pressure is the same as the temp. Factor heat from the engine and if you find less than that you are close to empty of charge.
Evidence is nice in combination with another test to peg a leak. Short of seeing it spit out a pin hole it's tricky. Problem with A/C is that a compressor is needed that also need lubrication only by oil the system uses and only when charge is adequate or it runs dry and burns out fast, throws debris not tolerate well which is why A/C get expensive fast.
Hope it cools when charged up with your new hose. I suggest asking the place to check for leaks as it might not have been the hose or could have been more.
Late now but best to disable a system that isn't cooling properly so you don't trash the whole system.
Let us know how it works out and hope for the best,
T
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Sidom
Veteran
/ Moderator
Feb 26, 2014, 10:50 PM
Post #11 of 11
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Re: AC does not cool enough - Compressor does not cycle and the fans stay on
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Sound logic.......Worth a shot....
Might want to think about having the shop change out the high & low side service valves & put in some dye while the system is empty.......The valves can be another common area for leaks.....
Good luck.....Let us know how things work out for you......
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