# A/C Problem, compressor turns on and off



## saga_child (Apr 13, 2004)

Hey guys, i've tried searching for the solution to the problem, but havent really found anything, anyway, my problem is that when I turn on my air conditioning, it will work fine for about a minute or two, then i can feel as the compressor turns off, and it starts to blow warm/hot air for a couple of minutes, but then the compressor will turn back on again, and it will start to cool off the air, but then it turns off, and on and so forth, in a vicious cycle. My sister's honda had the same problem, and she took it to a place and they had to replace some kind of relay. I'm wondering if I have the same problem? I've very recently had my condenser and high pressure hose replaced, and properly charged and I hope its not something more serious like the compressor. Any ideas of anything other than the relay? Also when I turn on my a/c I hear a squealing for about 5 seconds, which will get louder if I rev the engine in that interval, and afterwards just a slight squealing at idle, any suggestions?


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## thestunts200sx (Jul 11, 2005)

Find the relay and check it out / replace if needed.

If that doesnt work...then I can only assume the compressor has had its time. Which sucks...but you can find a replacement fairly cheap, even brand new.

Have you tried completely bleeding/draining the ac system and fully recharging it ? 

I dont know much about ac systems, but you could always call a shop and just tell what you told us....and theyll usually give you a good nudge in the right direction as to what it might be....and always end with a..."bring it in, and we can tell u exactly whats wrong with it" without saying....'for a 100 bucks'.

Anywho...good luck.


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## znamya (Sep 21, 2004)

Saga Child;

If it was my car, I would first bleed the system from the low pressure port. Then recharge the A/C with interdynamics Artic freeze or High mileage 134a. you can find it in target, walmart, autostores. This weekend I bleed my A/C then recharged it. When I was draining the coolant, my compressor was working like you explained, turn on and off and on. When I complelety drained it, it completely stoped working. Then when I recharged it, it is giving really cold air. Just try it as it is only 20 dollars solution...good luck


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## Ninety-Nine SE-L (May 5, 2002)

Typically this is somewhat normal, when you come to a complete stop on a hot day, the condensor gets very little air going through it. The compressor sometimes shuts off to prevent heatsoaking which can damage the AC parts and overheat your engine.

If freon levels are low, it can cause problems in the heat exchange and will cause the system to turn itself off to prevent damage to the condensor and evap. If something is preventing air from flowing through the condensor/radiator, it can also cause problems like this. Anyway, Check the freon levels, make sure the radiator fans are blowing while the AC is on, and make sure there are no leaves/junk trapped in the condensor/radiator.


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## trr4423 (Apr 17, 2005)

Sounds like you need to add some R-134a(freon) and a can of leak detector/stop leak to the A/C system.


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## IanH (Feb 11, 2003)

saga_child said:


> Hey guys, i've tried searching for the solution to the problem, but havent really found anything, anyway, my problem is that when I turn on my air conditioning, it will work fine for about a minute or two, then i can feel as the compressor turns off, and it starts to blow warm/hot air for a couple of minutes, but then the compressor will turn back on again, and it will start to cool off the air, but then it turns off, and on and so forth, in a vicious cycle. My sister's honda had the same problem, and she took it to a place and they had to replace some kind of relay. I'm wondering if I have the same problem? I've very recently had my condenser and high pressure hose replaced, and properly charged and I hope its not something more serious like the compressor. Any ideas of anything other than the relay? Also when I turn on my a/c I hear a squealing for about 5 seconds, which will get louder if I rev the engine in that interval, and afterwards just a slight squealing at idle, any suggestions?


The A/C cycles on and off to control the pressure in a band. 
There is a low pressure switch and when pressure drops too low this will turn A/C compressor off. This happens when the A/C load is low and or the Freon is low. 
There is also a high pressure switch. This protects the compressor and condenser from extremely high pressures. ( around 500 psi ) 
My car cycles on this switch because there is to much Freon in my system. 
This also causes the compressor to turn off and the system to warm up at idle speeds and a delay in turning on again. The low side pressure rises but the system will not turn on because the high side is still too high. My Singapore Sunny acted like this as well and the same as you describe. there was 0.65 Kgm of freon instead of the specified 0.45 to 0.55 Kgm ( B15 Singapore system installed at the port, this may not be the Nissan factory system.) 

So the answer is, as others have said, to get the system checked with a full set of gauges and add OR REMOVE freon to get the system balanced. 

I will also add that there is discussion about the factory fans not cooling the condenser in very hot weather, Phoenix etc and some members are adding an extra fan in front of the condenser. 
If the car is idling and you put water from a hose on the condenser and the pressure drops, system turns on ie works, this is a sign the system is overcharged (from the B14 FSM.) 

Good luck.....


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## saga_child (Apr 13, 2004)

well I had the system charged by a mechanic who I trust cause he is one of my brother's friends, and he has a machine for charging the a/c, and he looked at how much needs to be in there, but just in case I'm gonna take it back to him and see what he says about it. It might be that there is a hole somewhere, and thats causing freon to leak, but since we charged it with the dye also, its gonna show up, so I'll update you guys on how it goes, hopefully its not something major. As for charging it myself, I'd rather have him do it, since he has a special machine for it, rather than myself without any knowledge or tools. Also I noticed that on cool days or at night the compressor won't turn off, so yea it's probably not the relay as I was thinking earlier.


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## WiZzO (Jun 15, 2005)

i cant wait to hear what he says about whats wrong with it cause i am having the same problem with my car, even with it staying on at night...i'll pick up a gauge to see if maybe i have to much freon. How would you let freon out if there is to much?


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## IanH (Feb 11, 2003)

WiZzO said:


> i cant wait to hear what he says about whats wrong with it cause i am having the same problem with my car, even with it staying on at night...i'll pick up a gauge to see if maybe i have to much freon. How would you let freon out if there is to much?


If you buy gauges you should buy the two gauge set that measures high and low pressure. about $80 with hoses. 
If you need to let some freon out and you don't want to take it to a shop to have it done you open the valve on the gauge set and cover the end of the third hose with a rag to stop the Oil and dye from going every where and let it vent. There are some concerns with release into the enviroment but you will be releasing a small amount. On my Sunny it had 0.15 Kgm to much Freon.
Your Call.
Good Luck......


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## saga_child (Apr 13, 2004)

alright, well i got it checked, and there was one place where we saw dye, and that was at the first port, so just in case we replaced the shredder valve, and one of the o-ring on the metal hose (dont know what its called). Well when we charged .65 kg virgin refrigerant into there, the air that was blowing out of it was not really cold, and the compressor was making a really bad sound, as well as the squealing a/c alternator belt, so we concluded that the compressor is bad and that is why it is cycling and not cooling as well as it should. So since fall/winter is coming, even though the weather in utah seems to be staying summerlike, I decided to forego getting a new compressor this year and rather saving some money and getting it in time for summer next year, maybe I'll even go to my local pick-and-pull and find a good one there. Thanks for all your help guys, I really learned a lot.


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## funkpacket (Feb 13, 2004)

im hoping its not the compressor, because im having the same problem as the rest of you. When the car is moving the a/c is fine, but sitting at a light for more than 15 or so seconds my compressor shuts down. Its been 93 or warmer for two months straight here in florida, and this damn a/c problem means im pretty much driving with my windows down. Thats giving me 10 lbs worth of lost weight per day in sweat alone and a friggin sunburned left arm from it hanging out the window. Anybody know how much a compressor runs new?


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## saga_child (Apr 13, 2004)

at autozone I checked the website for my area and it said new compressor with clutch would be $550, obviously though autozone is not the cheapest but that should give you some sort of range I guess, I'm still confused as to why its the compressor, because on cool nights it doesnt shut off at all, but it does still shut off when im driving even without stopping, so I'd check for any leaks, and pump out the old freon and put in new freon, then if it still does that, I guess its the compressor, plus my compressor sucks, and my air at idle isnt even cold, its like lukewarm, only around 2500-3000 rpm does it start to get actually cold. Im guessing mine shuts off on hot days because it overheats because it doesnt work properly, does anyone know if the compressor can even do that? like shut off when it gets too hot to prevent it from completely dying?


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## WiZzO (Jun 15, 2005)

the compressor will turn off if too much pressure is built up in the system and as a safety feature the compressor will turn off, if you can get your hands on a manifold gauge set (maybe around $80 from a local autoparts store) check the pressure on the high port and low port and make sure they meet specifications if not on the set there should be a release valve to get the pressure down and if you need more just buy some more freon


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## pester (Dec 14, 2004)

znamya said:


> Saga Child;
> 
> If it was my car, I would first bleed the system from the low pressure port. Then recharge the A/C with interdynamics Artic freeze or High mileage 134a. you can find it in target, walmart, autostores. This weekend I bleed my A/C then recharged it. When I was draining the coolant, my compressor was working like you explained, turn on and off and on. When I complelety drained it, it completely stoped working. Then when I recharged it, it is giving really cold air. Just try it as it is only 20 dollars solution...good luck


yes just dont forget to do vaccum on the system and check for leaks with gauges

if is no leaks u r set to refill it

u will find a sticker in the engine compartment telling u haw much refrigerant u can put there

dont put more or u will blow the compressor ive seen them blowing before


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## nismomando (Jul 12, 2005)

when you recharge the system make sure you only put gas into the low side becouse if you put liquid there goes your compressor. i dont think your supost to charge on the high side but if you do make sure the car is off. i do service work on residential A/C's. also if the belt is loose the compressor won't work right so tighten or replace it.


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## funkpacket (Feb 13, 2004)

i just bought some r134a and a pressure gauge to test out the refrigerant levels before i added the juice. I was getting a reading of 50 kg/cm^3 when i first tested the line, but when the compressor turns off the pressure steadily builds to 95 kg/cm^3 and the a/c then starts to run hot. Since the initial reading is within the acceptable range for the ambient temperature of the test am i correct in assuming that the addition of r134a would accomplish nothing? Since the problem occurs mainly when the car is sitting at idle, might the problem lie somewhere with inadequate cooling/obstruction of the condenser coils? Both my a/c and coolant fans are working as they should, and the belt tension seems copacetic...i seem to be leaning towards the cooling of the coils as the issue


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## avindesai (May 13, 2015)

*nissan a.c. problem*

yes i aggreed. same problem of compressor on & off with hot air blowing i am also facing with nissan sunny. 7-times nissan service center has opened the a.c. & they replaced every thing related to a.c. Still problem not solved. for last 3-yrs i m using this car without a.c. cooling & nissan is not even serious about such complaints from their client. i have seen new brand nissan terrano with the same problem. i m tired now with this a.c. problem & now its a news of a town & known to every one. so difficult to resale the car now.


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## aldmarcris (Sep 27, 2016)

Continuously Switching on and off. This just happened to me while I was adding freon to the system. I solved it discharging little by little by the loading valve(at the times the compressor self switched off) till it stopped Switching off. If I did it at the ON state of the compressor it released wet gas with the green factory lubricant, at the Off state it releases a dry gas as a residual air in the pipes.


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## Shade Tree Squatting (3 mo ago)

saga_child said:


> Hey guys, i've tried searching for the solution to the problem, but havent really found anything, anyway, my problem is that when I turn on my air conditioning, it will work fine for about a minute or two, then i can feel as the compressor turns off, and it starts to blow warm/hot air for a couple of minutes, but then the compressor will turn back on again, and it will start to cool off the air, but then it turns off, and on and so forth, in a vicious cycle. My sister's honda had the same problem, and she took it to a place and they had to replace some kind of relay. I'm wondering if I have the same problem? I've very recently had my condenser and high pressure hose replaced, and properly charged and I hope its not something more serious like the compressor. Any ideas of anything other than the relay? Also when I turn on my a/c I hear a squealing for about 5 seconds, which will get louder if I rev the engine in that interval, and afterwards just a slight squealing at idle, any suggestions?


Nissan's in general have crappie wiring and the Sentra's have a known problem with the ac compressor plugs. Where the harness plugs in they have poor connections and overheat which melts them. You can't see it unless you unplug it and look inside the plug. I had the exact same problem. Repair; hardwire the unit and cut out the plugs. IF you replace an ac compressor on a sentra I recommend hard wiring the compressor Hope this helps!


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