Recirculation and AC problem

[Phifross]

Dear all,


Since two months I have a new problem with my car.
Forst I'm living in West Africa, where the temperature never drop below 25°C (77°F) during the day but normally it's always between 30°C and 38°C (86°F - 100°F)

I always ride the car with the AC on at 23°C (74°F) with the recirculation on.
Now it happen every day, suddenly when driving after 5 minutes or less the Recirculation is going off by itself... and I don't know why.... Sometimes it goes off and the AC will turned off at the same time but sometomes the Ac will stay on even the Recirculation is off.
In every case, when the Recirculation is goign off there is no reason because I'm far from 23°C (74°F) inside.
I turned it on again and sometimes the AC will turn on too but sometimes not.... but it goes off often, every 30 seconds... sometimes it's ok it will stay and both are working fine....

I have no idea where to search first.... It's an AC or compressor problem ? I don't think the compressor has a problem, because when working it's really cooling well and quick and there isno strange sound on the compressor side.

Is there a sensor to control the Recirculation switch ?

Can someone try to help me what to check first please ?

Thank you so much in advance.

[VStar650CL]

Since you have "set temperatures" I'll presume you have Auto A/C and not Manual. Since the A/C and Recirc are going out at the same time, there has to be an issue affecting either power to the control head, or which is causing the control head to take the A/C offline.

Does the display blank out when this happens? If so, you probably have a bad power or ground connection, or the control head itself is going bad.

Does the blower quit when this happens? On the Auto version, the control head will kill the whole system if the blower is detected as "off", and that feedback comes directly from the blower motor. So a blower which is stalling or going open circuit, or a VBC (blower resistor) which is dying, could both cause your symptoms.

It's also possible one of your sensors is going open circuit, causing the control head to think it's too cold to run the system. There are three sensors which can cause that, the Ambient (in the grille), the In-Car (near the driver's knee), and the Intake (on the evaporator). They're all "divided voltage" type sensors, so an open circuit or bad ground will cause the control head to think the car is in Siberia and not West Africa.

You can find complete information about your system here, with the electrical info starting on page HA-31:
https://www.nicoclub.com/service-manual ... 4%2Fha.pdf

[Phifross]

Thanks for your explanations.

The display working normally when the problem happens... nothing wrong on that side.
The blower will work but slower than when the Recirculation switch is one.

It means I have to check the sensors?
All right I will check them one by one.
Is there any way to proceed? I'm really not good as electrician!!!

Thanks again!

[VStar650CL]

Unless there's a wiring problem, checking each of the sensors is easy... BUT, you'll need to catch it in the act for the checks to mean anything. While the A/C is misbehaving, disconnect each sensor one at a time and use a small paper clip or cut safety pin to short the sensor connector. Shorting them makes the reading shoot to "maximum hot" (144F for most Nissan sensors). If the system kicks on as soon as you short the connector, you found your culprit.

[Phifross]

One question again...

In the manual on the HA section for the AC, air and so on...
Starting on page 39 there is the self diagnosis test.
Now on page 44 it's concerning three sensors, the ambiant sensor, the In-vehicle sensor and the Intake sensor.

Is it normal that the intake sensor temperature is going down when AC on ?
I guess yes, but I would like to be sure....
Because in the manual it is written: "If temperature shown on display greatly differs from actual temperature, check sensor circuit first, then inspect sensor."
This would be true only if AC is not on, correct ?

Oh I'm going to answer my question, on page 131 it is shown that the intake sensor is located on the evaporator....
"The intake sensor is located on the cooling unit. It converts temperature
of air after it passes through the evaporator into a resistance
value which is then input to the auto amp."

Also everything is all right !!!!!

Thanks to everyone !!!!

[VStar650CL]

Your answers to your own questions were all correct.

When you originally posted, I neglected to ask how you knew the recirc was turning off. With 20-20 hindsight, if you're judging that by fan speed and not because the Recirc lamp is turning off, you might just have a bad Thermal Expansion Valve (TXV) which is freezing your evaporator. The TXV is like an evaporator thermostat, designed to allow more refrigerant through when the evap is warm and less once the evap gets cold. Bad TXV's typically stick open, so they'll cause the evap to ice over from excess refrigerant. This will cause the airflow through the system to suddenly drop and the fan to sound faster as the evap ices over, but then the system will work normally again after it's shut off for a few minutes (because the ice melts). TXV problems will show up most when the A/C is working hardest, high temperatures and high humidity -- which is to say, normal conditions in your part of Africa. If the symptoms above match your experience, change the TXV.

[Phifross]

Thanks a lot for this advice, I will monitor it.

To get part it takes time here.
What I did first I changed the Fan Control Amplifier.
I brought à cheap one on Amazon, around 20USD.
It was working fine, no problem at all for 3 weeks and the problem starts again randomly...

Also I was suspecting something différent to be the cause of the problem.
But now I have controlled almost everything except what you told me... also I suspect the Fan Control Amplifier to be not good.
I have brought another one from STANDARD MOTOR PRODUCTS RU788
I change it today, also I will see.
But I will also monitor what you said.

One question, my evaporator was really dirty, do you some tricks in order to clean it?
There is not much space there.... the plastic box, I was not able to remove it....

Thanks a lot!

[Phifross]

For the recirculation, it was the light turning off...

[VStar650CL]

For the recirculation, it was the light turning off...

That's different, but it's possible the system is designed to kill the recirculation when the evap temperature goes too low (which it would if the evap iced over). Those are the sort of software details that Nissan never gives us, so we end up guessing. I can only tell you that there are some swash-plate systems which definitely do that, and your compressor is a swash type.

One question, my evaporator was really dirty, do you some tricks in order to clean it?
There is not much space there.... the plastic box, I was not able to remove it....

There aren't any good ways to clean it. As you noted, it's buried in the HVAC box. They do sell sprays which can flush away some of the grime, you remove the cabin filter, turn the blower on high, turn the temp to full hot, then spray into the cowl so the stuff gets sucked through the evap and heater core. If you have a lot of debris in there (as opposed to grime) it usually means your cabin filter is crumpled or clogged and stuff is making it through the blower cage. The only way to remove some of that is to yank the blower motor and stick a vacuum cleaner nozzle through the ingress duct.

[Phifross]

Also since I change the Fan Control Amplifier, it's better but not perfect.
At least I don't have the fan going as crazy, very fast, suddenly very slow and the AC is on almost always.

But still the air circulation when I turn it on, after few seconds it will turn off by itself.

Is there any switch, control or sensor for the Air circulation?
If yes where it is?
Easy to replace?

Thanks a lot for your suggestions

[VStar650CL]

The recirc is a servomotor controlled by the head unit, so it's driven by smartwork and not a switch. The only thing the FSM shows that cancels it is if you have the mode set to defrost or foot-defrost. In those positions it automatically goes to outside air.

[Phifross]

Oh.... It means something is messing up with that recirculation...
Because I'm not using defrost at all here....
Interesting....

[VStar650CL]

Like I said, it could be something with the evap temperature. Sadly, it's pretty normal for Nissan to put stuff like that into firmware and not tell anybody. Flowcharts from the firmware vendor would save a lot of headscratching, but nooooooooooo....

[Phifross]

I'm not sure, because I start the engine in the morning, the AC come on right away, I'm on automatic... I turn on the recirculation and after 10 to 15 seconds it turns off by itself....
It's not long enough to have ice , the AC was on for less a minute....

If you have any idea, it's very welcome!!!

[VStar650CL]

If it's on Auto then the HVAC is probably deciding whether the recirc should be on or not, based on its own parameters (no, don't ask me what those are, only some programmer in Calsonic's basement knows the answer). See if it still happens if you bump the fan speed first (that puts the whole system in manual mode). On some of the older HVAC's you have to push the Recirc button twice to give the HVAC auto control of recirculation, and the owner's manual says your Pathy is one of those -- BUT, the silly Japlish description doesn't tell you how to take it back out of auto recirc mode. So you might try messing with multiple presses of the Recirc button to see if that has any effect.

[Phifross]

Also.... finally I'm going to give up....
I have tried yo press the recirculation button for 10seconds...
Looks like it was ok.... for a week....
After it becomes crazy again, recirculation going after 5 seconds... blower going fast or slow suddenly etc...
but now, since a month it's going fine... the recirculation is almost never going off and the blower motor is no more going crazy but it stays stable, correct speed.

Why, I don't know I have not chaged any parts...

Do you think, if the battery is not good, if the voltage varies, it can trigger all this crazy things?
As for me I can't see anything else...

Thanks a lot for your precious help, I really appreciated it much!!!

[Mike W.]

I know quite a bit about cars in general, but a much more modest amount of knowledge about these cars, but I do know some. VStar650CL for instance knows a whole lot more that I do. However, what I have figured out is at least on my QX4, it's programmed to act like they think it should work. They didn't care about you or your preferences, they knew better. Sitting in a cubical in Japan, they know better than you what is comfortable, and they're going to limit your options because they know better than you what is comfortable and what isn't.

In other words, it's entirely possible what you are trying to fix is unfixable because it's working as they designed it to work.

[Phifross]

Thanks a lot to everyone.

Mike I agréé with what you said.
My problem is just that before it was not acting that way.... it means something changed... but I don't know why...
But I understand that it is a tricks problem... and at the same time because of their own programmation we don't have really the possibility to check what's wrong.

Again thanks a lot to everyone!!!

[Phifross]

Dear All,


I'm still investigating the problem I got.
I would like to change some parts, knowing maybe it will not solve the problem.

I have checked the In vehicle temperature sensor (M34) it was really dirty.
I cleaned it but still it's not consistent. Sometimes the AC turn on, sometimes not even very hot.
The recirculation keeps going off after sometime....

I don't know which one need to be changed among these three things.
Intake door motor M59
Mode door motor M38
Airmix door motor M55

Or do you think there is something else to change?
What is funny that every time I'm doing the trouble diagnoses on page HA 40, the different steps, all of them are working fine, never had anything not working, but as soon I quit the diagnoses mode trouble starts...

Thanks a lot for your precious help.

[VStar650CL]

If it helps, the functional descriptions for the motors are:
Intake - Controls fresh/recirculate
Mode - Controls Foot/Vent/Defrost
Mix - Controls temperature

On an Auto system you also have two additional sensors which can affect system performance, the Intake sensor (temperature of the A/C Evap) and Ambient sensor (outside air temp, sensor located in the grille). The Mix and Mode motors also use potentiometers (PBR's) and are true servomotors, unlike later models. When the position pots fail they sometimes get "bad spots" instead of going flatline, and that can cause the motors act erratically. There's no way to measure that because the pots are internal, but if you read the positions with an HVAC-capable scanner you can see them jumping around. The Intake motor has switches because it only operates in 3 positions, Fresh, 20% Fresh, and Recirc. Those can be checked with a voltmeter because the signals go by wires to the HVAC head.

[Phifross]

Also it's my intake that is not working properly.

Do you where I can find one please?

I also need the "wood like" cover for the central air vents.
My own brakes like glass today.
The air vents are fine, the clock in the Center is fine too.
Do you know also where to get one please?

I was not able to find one anywhere.

I don't know how to put à picture here too...


Bad day today....

[VStar650CL]

That woodgrain trim always self-destructs and I don't know of anybody making woodgrain replacements. Last time I looked was a couple years ago, but I did see a couple vendors on eBay who were printing and selling black ones for R50's.

The intake actuators show still-available from Nissan, p/n 27740-40U00, but they're very pricey, about $230 online. I don't know if there are cheaper alternatives, you could try the Part Search tab in RockAuto.

[Phifross]

If it helps, the functional descriptions for the motors are:
Intake - Controls fresh/recirculate
Mode - Controls Foot/Vent/Defrost
Mix - Controls temperature

On an Auto system you also have two additional sensors which can affect system performance, the Intake sensor (temperature of the A/C Evap) and Ambient sensor (outside air temp, sensor located in the grille). The Mix and Mode motors also use potentiometers (PBR's) and are true servomotors, unlike later models. When the position pots fail they sometimes get "bad spots" instead of going flatline, and that can cause the motors act erratically. There's no way to measure that because the pots are internal, but if you read the positions with an HVAC-capable scanner you can see them jumping around. The Intake motor has switches because it only operates in 3 positions, Fresh, 20% Fresh, and Recirc. Those can be checked with a voltmeter because the signals go by wires to the HVAC head.

If I understood well, you think that if the intake sensor have a problem, it would not act erratically but it would not work at all?
If it works erratically, there is more probability that the problem come from the Intake sensor or the Ambient sensor?

Is it what you are thinking?
I need your advice because everything related to electronic is like Chinese for me... of course I'm not chinese

Thanks a lot for your patience!!!

[VStar650CL]

The behaviors you're describing are so erratic, I'm not prepared to tell you what I think is the cause. I'm only prepared to tell you all the things that could be the cause. Bad contacts in the Intake Door Servo are a possibility, since resistance in those can make the head unit think the door is in the wrong position. Sensors can cause it too, but since you aren't electrically inclined, I can't exactly give you advanced diagnostic procedures. If you're going to throw parts at it, the best advice I can give you is to start with what's cheapest and easiest and work your way down the list.

[Phifross]

I understand.

Sorry to give you hardtime do you have the part number for the Intake sensor (temperature of the A/C Evap) please?

For the ambiant sensor it's ok I found it.

Thanks a lot!

[VStar650CL]

The Intake sensor should be 27723-2J500, but it shows discontinued and IIRC you need to pull the whole blower box to replace it, so it isn't easy.

[Phifross]

Also let me come back on this topic.

I have changed my In vehicle temperature sensor.
I have done this because when doing the auto test to check the temperature sensor, for the Invehicle sensor it was erratic.
I was performing several time the test with just 30 seconds interval, and I had more than 5 degrees difference between the measures... sometimes going up or down.

The other two sensor the reading was always constant.
For example for the evap, after the AC was turned off the temperature was going up step by step.

Just to let you know, all the others steps on that are working fine, when the AC has to be one, it's turning on, when it has to be off it's off.
When the blower has to be working 100% it's 100% and ghe different direction, foot, face window... everything is correct when I'm performing that test.

Also I change the in vehicle temperature sensor and it was working OK.... for a week....
And again it starting to work erratically.
It's less crazy than before but still not well.

Now we are in rainy season also the temperature is around 26 degrees when rainy and it's working very well.... but so often when the temperature raise it's working more erratically, for example the sun is shining and the car was left under the sun.... at that time it will take long for the AC to turn on....

Do I have to check the two other temperature sensors if really they are OK even if during the test the reading temperature is OK?

Do you feel something else is the cause?

Thanks a lot.

[VStar650CL]

The sensors are all "RTD" types, they're just resistors that change resistance with temperature. When a sensor gets bouncy the way you're describing, it's usually a wiring or connector issue causing the misbehavior, not the sensor itself. Check the pin-fits on the in-vehicle sensor connectors at both ends and make sure nothing is corroded. Also make sure the ground side connection reads no more than an ohm or two to the chassis.

[Phifross]

Alright.

Sorry to ask this question, how to check the ground connection please?
Which PIN it is?
Is there a black color wire to that pin?

Sorry... electricity is not my domain but I can learn.

Thanks a lot.

[VStar650CL]

According to the FSM the signal wire should be Pink/Blue, the ground should be Green/White. Use an ohmmeter with the sensor disconnected, red lead on G/W at the sensor connector, black lead on the chassis. Anything above about 2 ohms means there's a contact or corrosion issue in the ground path. Note that the sensor grounds through the circuit board in the control head, so a high reading could mean a generic issue with the control head ground and not necessarily an issue in the sensor wires.