A/c Help.

[trulyphly710]

I have been having trouble with my AC lately.Sometimes it will be ice cold and sometimes it wont work!!I've been looking up the info on here for couple hours and the conclusion i came to was that MY Aux fan was bad. However, after i came to that conclusion and went outside. My Aux fan started working again. I have noticed that when my AC doesnt work, that my AUX fan is not turning.

Could it be that My AUX fan motor is going bad or is it something else? I have already played with the Relays and switching it out with other relays didnt change nothing at the time. The fan still didnt work yesterday when i played with the relays. Please help? Thanks.

Also. if its the fan. does anyone have one? You can email me also. Thanks!!!

-WoO

[navysnail]

check to see if the fan is getting power when it should be running but isn't.

you still have your engine fan right?

[benemorius]

Check a couple of other things, too: Is the green light on the a/c button lit when the a/c isn't working? Is the compressor turning when the a/c isn't working? (the pulley on the compressor is always turning, but when the "face" of the pulley is turning, that's when the compressor is turning)

[trulyphly710]

The Green light on the AC comes on. I do still have my Engine Fan. I will check and see if the Compressor turns today! and let you know what happens. I am guess it does turn because the air does come out cold still sometimes..

[benemorius]

Well obviously it turns and the light comes on if it works sometimes, but what I'm asking is whether they're still on when the a/c is not blowing cold air.

[trulyphly710]

Yeah the light stays on!

[benemorius]

Ok. Now how about the compressor?

[trulyphly710]

some reason now. the AC is working like everyday. i have no clue. and since it has worked, i havent messed with it since. But the Ac does get warm sometimes on really hot days. thats about it.. UI just think its weird how it solved itself when i was about to check it

[benemorius]

Intermittent problems can be so hard to diagnose.

Next time it stops working tripple check these things for me just to be sure. It's important we get the details right because I don't want to tell you it can't be something when really that's exactly it.

-green a/c light still on?-compressor still turning? (not just the pulley... make sure the clutch is engaged so that the front 'face' of the pulley is turning)-aux fan turning?-idle speed normal or at it's a/c high idle?-how hot is the weather?-car in motion or sitting still?

Also, what car/year is this exactly? And is your radiator fan shroud still properly attached?

[trulyphly710]

Intermittent problems can be so hard to diagnose.

Next time it stops working tripple check these things for me just to be sure. It's important we get the details right because I don't want to tell you it can't be something when really that's exactly it.

-green a/c light still on?-compressor still turning? (not just the pulley... make sure the clutch is engaged so that the front 'face' of the pulley is turning)-aux fan turning?-idle speed normal or at it's a/c high idle?-how hot is the weather?-car in motion or sitting still?

Also, what car/year is this exactly? And is your radiator fan shroud still properly attached?

The Green light is on. The Compressor isnt turning. The Aux Fan is not TurningThe idle speed is normal.The weather was about 92+ Degrees Car was in motion and still.

Car is a 92 AUtomatic hatchback w/ Hicas just in case it matters in this situations.

However, i played around with it and found the electircal lines next to the fuse box. and then all of the sudden the compressor engages and then when i snap it back on, the AUx fan starts working and the idle goes up also. What needs to be done? does the wires there just need some cleaning? I was in a rush to work so i didnt have time to try nothing on it yet.

Thanks

[benemorius]

Excellent work on getting the details down verbatim. (you'd be surprised at how many folks just won't cooperate )

This is almost certainly an electrical issue, but I'll start with the one exception. How cold is the air coming out of the vents JUST BEFORE it cuts off? If it's significantly colder than normal, then the problem is that the evaporator core is getting too cold and the ecu is shutting down the compressor for safety. Having said that, I do NOT think this is your problem but I have included it for the sake of being comprehensive.

Now as I said I think it's electrical. Either the evaporator core temp sensor is malfunctioning (less likely) or you have an iffy connection somewhere (more likely.) It will be somewhere between the a/c relay in the driver side relay box and the ECU, or the ECU and the evaporator core temp sensor. It really can't be anywhere else based on your input. Points of interest would be the a/c relay itself and the connector for the temp sensor. Keep fiddling with things every time it cuts off until you zero in on the problem area. That's generally the best stragety for an intermittent problem like this.

EDIT: The connector for the evaporator core temp sensor can be most easily accessed by opening the glove box WIDE open. (there is a rubber stop on each side of the box - flex the box one side at a time so as to open the box beyond it's stop-point) The evaporator core box is the black box directly behind the left side of the glove box. The temp sensor connector is the small white 3-pin connector almost at the very left-bottom-most corner of the glovebox opening.

[trulyphly710]

ok! Thanks! I'm going to have to look more into that and i will let you know! I am going to post a picture up tonight or tomorrow morning of the switchs(its those switches that connect the wires kind of like the ones on the Acc Fan) When i disconect the one for the fan. the Fan will not come on but the AC engages. Maybe the picture will help explain what im trying to say since im not too familair with the Technical Jergon.

Thanks!!

[trulyphly710]

I have a question again!? It still does it again. I called Nissan and they dont know what the Evaporator sensor is. Is it the same thing as the Thermistor? or something Do you know the part number? im beginning to think thats the problem..

While the a/c works its real cold and then it gets luke warm and cuts off. Thanks again. and how much does the part run about?

[chad_KAT]

Sounds like you might have a bad pressure switch.... check you static pressures with a manifold gauge and have someone that is 609 certified do it for you and so you dont get air in the system.

If your presssurs get low becasue of low refriderant the switch will not let the a/c comprssor to turn on but if your static presssurs are good at a given ambient tempature then it could possibly be a pressure switch.. the pressure switch could be located on the reciver dryer or the accumulator dryer... check the switch to make sure its good( look at the fsm for diagnosis of the switch)

and one more thing if you find you have low Refridgerant that that means you have a leak. hope this helps

~Chad

p.s dont let the EPA catch you servicing your a/c unless you are certified otherwise its a 32,000 fine and up to 5 year in prison lol im sure you dont like butt sex. and rember the EPA's funding is not from the goverment its from fines.

[benemorius]

Lets not confuse matters. Based on the input given, it CANNOT be low/high pressure or a malfunctioning pressure switch. It has to be an electrical issue somewhere from the a/c relay to the ecu to the evaporator temperature sensor.

Yes, the temp sensor can also be called a thermistor, but please don't go replacing parts if you don't know they're bad. Nobody likes to waste money. It is not likely that the thermistor would cause intermittent operation. It would more likely cause consistantly poor operation. Intermittent operation is much more frequently caused by a loose connection. Keep playing with wires and see if you can find something loose. If you poke something and the a/c kicks on, then you've found the problem area. As I said, points of interest are the a/c relay and the CONNECTOR for the thermistor.

[nissanconvert]

I know this thread is old but it sound like you might know whats wrong with my a/c by the first question you asked benmorious.

The green a/c light does not come on?in fact it seems as if hitting the button does nothing no motor change in speed etc.aux fan turnsclutch for a/c nto engagingtried in various weather moving and still

anybody have an idea of what to start looking for?THanks

[benemorius]

Are you sure the fan is turning on when you push the button? That's almost not possible if the green light doesn't come on.

[nissanconvert]

Maybe I'm confused, the fan for the climate control on the slider comes on, the radiator fan is alway on, if there are more they are likely not coming on because nothing happens when the a/c button is pushed

[benemorius]

The fan you speak of is commonly called the blower fan. The aux fan is an electrical fan mounted to the front of the radiator (technically it's on the condenser, but forget I mentioned that)

Assuming now that your aux fan is in fact not coming on, I would first suspect that your system has leaked out all of its refrigerant. The easiest way to check for that is to remove one of the two caps on your system (you'll find them on the two metal pipes coming out of your a/c compressor) and use a small pointy thing to push in the valve. It's just like letting the air out of a tire. If nothing comes out, then you have no refrigerant.

[nissanconvert]

Ok, i found the aux fan, i missed it being hidden between the radiator and other fan. It indeed does not come on. THe red and black capped line both have some pressure feels like when a tire is almost flat, my guess would be not much. Would this be somthing an ebay r12 refil kit would fix? To check for a leak it has to have engough freon to run first right? I checked the lines and there are no oily spots or rust as far as i can tell, in fact it looks as if the lines are aluminium.

[benemorius]

Do you know the history of this car at all? Due to the fact that you still have some pressure in the system, you honestly might just be able to recharge it and be ok until it leaks out again. Unfortunately it is frequently almost impossible to know the history of an a/c system and in that case the only safe answer (in my book) is to have it completely flushed and refilled.

I guess my recommendation is this:

Look at the two caps again. Is one larger and red, and the other smaller and blue? Or are they both the same size and perhaps the same color? If they're the same, then you still have r-12 fittings and you just might want to try refilling with r-12. The thing is that it's just so damn expensive and I really don't want to see you waste all of it out a leak somewhere. You might be able to borrow a leak detector from somewhere and try to locate the leak as you recharge it.

If the caps are different sizes, then you have r-134a fittings. If you can't find a retrofit sticker anywhere on the underside of the hood or by the drier, then I would have to suggest that you have a qualified person flush the system, replace the drier, and refill with r-134a and PAG oil. Too many systems have been retrofitted to r-134a by someone who doesn't know what the hell they're doing and the best way to minimize the chance of failure down the road is to start over fresh. I'm not saying it won't work if you don't do it this way. I'm just saying that this is how it's done in my book.

[nissanconvert]

The history is entirely unknow to me, i bought it from a shady dealer with a clean carfax to later find out that the entire back half was welded on from a differnt color car and the front from the radiator forward was replaced. I'ts been an interesting time from missing vacuum hoses to a miswired dash to a smashed and leaking fuel tank in side a pristing rear end. But i digress...

Both caps are the same size, one is black and the other red. THere is no retrofit sticker but that is not saying much as I'm sure most of the front end is from a differnt car also.

I've seen a lot of 143a systems and recharged a few as a brief stint as a valvoline instant oil change employee and this doesn't look like one at all.

I'll refil it and take it from there with leak testing if it turns on like it suppsoed to. If not, I'm not too concerned, it's a convertible and was just looking for somthing to use on the really hot days.

You've been a big help, thanks!

[benemorius]

Good luck to you, and be sure to come back and let us know how it goes.

[nissanconvert]

Huzzah! Working r12 a/c for $120 and a scar(the exhaust is hot!!)Recap:a/c light did not come on or clutch or fan either.High + low side had 20psi when off.

After reseach this is what i came to conclude.The system is old and seals are likely dry, whe i tested the pressure it was dry freon coming out. Since it was holding pressure there is no massive leak.

Optiions:Recharge r12 or retrofit 134a or use alternative.

Decision: recharge r12 for best chance. using an alternative works less, costs more and makes it unfixable later by any tech or shop for libility reasons. REtrofitiing properly is expensive and time consuming. $600+. The auto parts store retrofit in a box is baloney, the oils are not compatible, the system isn't designed for it and it will likely break down the road costing more. Recharging r12 is fairly easy and nto that expensive once you know what you're doing.

1st step, get freon. If you don't have r12 on a shelf you need to buy it. It is legal to buy and use if you have the EPA license for it. I got the license by taking a online test. It's $20, 25 multiple choice question and takes 1-3 hours depending on how you study. Also it is open notes. 21/25 gets you a pass. I did it in one evening. Now you can go on ebay and buy the r-12, hoses, gauges and tap. One seller has recharge kits that work great. $90 +13 shipping gets you 3 12oz cans, toyota 1.4oz swash plate oil(240sx is swash plate compressor) and tap/gauge. I borrowed a good hi/low pressure gauge to save money.

Thats 120$ including certification, which is less than valvoline charges to top off r134a!

I used 2 and 1/8? cans of r12 and the 1.4oz oil to get the system up to pressure. 148psi high/40psi low side, ambient temp 72, humidity 100%(raining). With full a/c on recirc mode i got 40 deg. F in the center vent. Good enoguh for me since it never worked before. THe high pressure is likely too high and low pressure is too high according to the manual but the system is 14years old and this is the first time i've worked on an a/c. I had to jumper the low pressure switch to get it running to take the first 2 cans. It the 2 wires coming off the top of the can with the bubble sight.

Look online if you don't know how to charge the freon (only low side! with can up NOT UPSIDE DOWN!) Took 40 minutes per can i guess for me? Bleed the fill hose lines to get rid of air between can and system. etc.etc.

Hope that helps. You too can have cold a/c for relativly few dollars and done in one afternoon. greatest part is its still origional so if it goes bad later you're not stuck. You can still convert later if you want.

I'll be gone until july 26th and can't get inet so if you have urgent question i can't help. If it can wait, just shoot me an email and i'll help as best i can.

[benemorius]

Wow. Major props for doing all your homework. It's rare to see someone who will sit and research something so fully before asking a dozen questions and/or attempting to do something they aren't prepared to do. I was already cringing when I saw you had done the work yourself, then you proceded to impress me sentence after sentence.

[LiteraryCannon]

What I dont understand is.. why does the green light on the a/c button not come on if you do not have freon in the system?......

Or did I miss something? nissanconvert said his green light didn't work.. then he filled his system with R12 and everything is working? Including the green button?

I am in a similar pickle..

[benemorius]

It is a common subject of confusion. I cannot vouch for all makes and models, but in the particular case of the s13, the green light is actually controlled by the ecu. It is not simply controlled by whether the button is pressed in or not. Most people think that if the light doesn't come on then it must be an electrical issue, but this is not the case. The button tells the ecu to turn on the a/c. The ecu takes input from the evaporator thermistor and the dual pressure switch on the receiver/drier. If it senses conditions which are outside normal parameters, it will not engage the compressor or condensor fan and it will not light the green light. When you have no/low refrigerant, the dual pressure switch senses this and reports it to the ecu. Thus, when the system is empty the green light will not be lit.

I believe that many/most cars do not behave in this manner so let me repeat that the s13 240 is at least somewhat unique in this behavior.

[BlackHat]

Let's say My 89 Nissan 240 was still using r12 and I wanted to convert it to r134 (I know my coolant leaked out an would rather use r134). What would one have to do to make that change? Do you just need to change out the nozzle or do you need a different compressor or what?

[benemorius]

Make sure that all the refrigerant is completely gone, first. If there is even one psi left then it would be better to refill with r12.

I would recommend changing the expansion valve, but I would not call it entirely necessary. You don't actually need to replace anything other than the drier. The compressor and hoses will almost certainly be fine. Obviously you'll need to take care of that leak first, and any hoses that you disconnect will need to have new orings installed. I would also recommend completely flushing all the old oil out of the system, but that isn't entirely necessary either. Be sure you have it filled by someone qualified or you could be disappointed.

[BlackHat]

This is, unfortunately, one of the things I won't be doing myself. I plan on having a mechanic or even the local nissan dealership do it.

Thanks for the advice!