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ac problems on 2001 nessian frontier
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rodmartin380
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Jul 28, 2008, 3:09 PM
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ac problems on 2001 nessian frontier
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2001 nessian frontier, the ac will blow cool air sometimes and other times it blows hot air. the syetem has been charged.
(This post was edited by rodmartin380 on Jul 28, 2008, 3:11 PM)
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Tom Greenleaf
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Jul 28, 2008, 10:23 PM
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Re: ac problems on 2001 nessian frontier
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Is compressor staying engaged? Condenser fan staying on? Need to know that. How do you know charge is correct?
T
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rodmartin380
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Jul 29, 2008, 1:33 AM
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Re: ac problems on 2001 nessian frontier
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HI, The compressor engages but it wont stay, the ac cools well when it is engaded. The syetem was recharged after the high pressure line was replaced. The fan does not stay on.
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Tom Greenleaf
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Jul 29, 2008, 3:16 AM
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Re: ac problems on 2001 nessian frontier
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Ok: The compressor is almost certainly shutting down for a reason yet to be diagnosed.
Does this happen routinely at a certain speed and come back on after a certain amount of time?
Did this just happen with the hose replacement and what was wrong with that hose?
Sorry - All questions. So you know, I'll be asking for pressures next when I get a feel for when this happens and what happened to the original hose,
T
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rodmartin380
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Jul 29, 2008, 2:16 PM
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Re: ac problems on 2001 nessian frontier
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Hi, There is no pattern somedays it work fine and otherdays it does'nt. The ac worked fine but the hose had a leak so i replaced it and recharged the system to 35psi. it worked for a few day then it started this. I drain the system and charged it again, but the problem continued.
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Tom Greenleaf
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Jul 29, 2008, 2:23 PM
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Re: ac problems on 2001 nessian frontier
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Did you hold a vacuum on this system before charging with refrigerant? If not you'll have to start over.
Don't guess, how much refrigerant by weight did you add? It calls for 25 ounces. 23-27 should work but better if on the mark,
T
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Tom Greenleaf
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Jul 29, 2008, 2:39 PM
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Re: ac problems on 2001 nessian frontier
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Too add to that. I think this is a TXV system. Low pressure only means little about how much refrigerant is in the system. It could be way too low or high and shutting down. Air will cause wild pressures and shut down.
The low pressure only means something in relationship to the high pressure and the incoming air at condenser and output temps.
Even small amounts of air have moisture which will frost up internally, make acid out of the oil if left too long.
Rule of thumb: Vacuum should hold by itself at 29.92 Hg at sea level for a minumum on 30 minutes. Allow about 1Hg less per 1,000 ft elevation,
T
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rodmartin380
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Jul 29, 2008, 2:46 PM
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Re: ac problems on 2001 nessian frontier
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No i did not hold a vauum on the system, my Haynes Repair Manual did'nt tell me to do that or how to do that, not sure how much refrigerant by weight. the charge kit said 30 to 40 psi so i added 35psi. how do I hold vacuum? I will try again.
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Tom Greenleaf
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Jul 29, 2008, 5:46 PM
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Re: ac problems on 2001 nessian frontier
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http://www.autoclimas.com/...igerant%20charge.php Worth the read and print even.
Ok: You'll be ok if you act quickly. Cough - what's in there has to go.
Manuals and kits for A/C should just plain be outlawed but here's the scoop. You are lucky in that your system holds almost exactly (2) 12oz pure R-134a sold in cans - no need to measure as that will be fine for the total charge.
Expansion valve is probably suffering a heart attack right now and will respond in all likelyhood if you go get a vacuum pump and gauges. You should get a can tap and then if your hose thing hooks up with its gauge use that for charging or get one that fits a can tap. There are can tap hoses that will run thru real gauges, look ask, buy what you need. You can rent the pump and gauges free (?) at some AutoZones stores and perhaps others.
Get acquainted with the gauges, knobs and will either have self checking connectors for high and low or in-line shut offs.
Either way you need to hook up vacuum pump and vacuum out the gauges with knobs open and in line shut offs, off. Both will show a full vacuum or should. If they are the check valve ends that don't allow air back in or refrigerant out until connected just test and see what you get.
When car is at zero or near zero hook up and run pump till you read the 29Hg thing. Turn knobs off and you are reading the car and back open you are reading the pump. Now shut down (turn knob) high side and continue vacuum till you see the 29Hg again. Shut knobs and pump off and look at gauge. Now wait out the 30 minutes and the needle shouldn't move. If it moves in a couple minutes, vac again and repeat. If it fails again there's still a leak to fix.
If it's all systems go and you have a can tap and hose that fits where yellow one goes on manifold gauges take the hose off at the manifold and hook up can that is ready to charge - after peircing and spit out just a spit of air out of the line (remember no air allowed!!) and when hooked up to gauges with knobs still off and holding the vacuum open the can tap turn whatever that allows gas to flow to open and now you are reading the pressure of the can on the gauges if there are in-line shut offs leave off and just low (blue knob) open. If check valve ends leave both shut and turn can upside down and charge liquid into high side just into the vacuum it should eat most of the can without starting the car. Can will get cold so warm it up in hands or use warm (not hot) water and pressure will equalize with the vehicle. Now you have to make the car suck in the rest of the charge. Start car and blast A/C. Just use low side now and watch pressure of high side just for fun but we know (I hope) it will be fine. Second can should only be used right side up meaning "gas" only and it will take longer with compressor running but it will empty it and when it warms up in your hands it's about done or equal to the vehcile's pressure on low side. Rev engine if you need more low side suction and mist water over condenser if needed.
You may want an extra can of 134a if one screws up you'll be able to start over yet again. If all works well you'll have most of the 24 ounces of the two cans in the car minus a miniscule amount for purging the hoses. Just the spit thru hoses doesn't weigh a measureable amount if not overdone.
Now you are just 1 ounce low but system will (should) operate near perfectly at just that amount low. Drive it and test it out.
What's missing is the 1 ounces and 1oz of PAG100 oil. They sell 2+2 134a-oil charge cans and you could just put some of that in guessing at about half the can. It would tolerate the extra ounce of each but keep track of this for future as oil can't be measured unless you flush every item out and replace drier which you should anyway and then you would need the whole 2oz of oil.
When all buttoned up just watch temps at vents as your guide to system performance.
You'll see tons of info in the link and do read that fully and understand it. High side pressure should be about twice the pressure in PSI as the temp of air entering grille.... 2.2 to 2.5 is acceptable. Low side will vary but would be about 20-30 give or take with this when engine rpms are raised to about 1200-1500 rps. Bet Haynes didn't tell you that's the rpms that pressures are taken! Idle pressures could be way off.
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Notes: If you can leave the vacuum held long so much the better. Water (known in there now) will boil off and be removed by a full vacuum. Vacuuming doesn't remove significant amounts of oil by itself. It is arguable as to whether it removes moisture from dessicant (in drier) and the oil which is a water absorbing oil but I don't think I'd trust all moisture to come out. It take some time with exposure to air for oil to go bad and tha vac can only help.
----What probably happened is the air scewed up pressure and the system shut down. Expansion valve may have taken a hit but frequently a vacuum and charge up will snap it too again - hope so.
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You are not alone with the misinformation out there in manuals and on products. I probably just wrote more than your Haynes said on A/C just now off the top of my head and probably confused the heck out of you but I can type like a race horse and when I re-read this will find some mistake but I think it's about right.
Good luck and stay cool,
T
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rodmartin380
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Aug 28, 2008, 10:38 AM
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Re: ac problems on 2001 nessian frontier
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Thanks Tom, you were right-on with yourdiagnosis of my A/C problem. It took me a while to understand what to do but i got and the AC works great. Thanks again and keep up the good work.
rod
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