Can someone do me a quick A/C favor please (R134a systems)

[MJK]

So I replaced the climate control board a few weeks ago with a new one, and was all looking forward to using the luxurious 'full auto' mode. It worked, but the temperatures were off! I had it topped off with refrigerant today, and still no help. I went through the troubleshooting guide, and found out that my outside temperature sensor was disconnected. Fine, reconnect it. Mild, if any, improvement. 63 deg on full auto does NOT produce 63 in the car. Ditto 88, 66 etc. The car blows ice cubes at 60 and fire at 90, but is a little wonky in between in 'full auto' mode. If I use the fan and temp knobs manually, all is as it should be.

The service manual points me in order to the following for these symtoms:
1. Outside temperature sensor From the resistance specs, the outside temperature sensor is within 10 degrees of accurate but not completely. BUT I cannot make certain of the any corrosion that may be in the female side of that connector without hacking at the harness. The harness does produce the proper voltage spec by a DMM. *note the online (r12) manual is different/ less detailed from the 93+ (r134a) manual in this section
2. The climate control board (mine is new)
3. The inside temperature sensor/asprator fan. Fan works perfect and is clean and quiet. The temp sensor is exactly on spec resistance wise. *again, per the different 93+ manual

Here is what I would like to know from anybody who wouldn't mind doing me a favor (before I go off ordering a new parts again):
A) How close to spec is your outside temp sensor? (easy to check, just unsnap and check the impedance - it right behind the center crossmember in the main opening of the front bumper). Mine is off about 10deg F @ ambient temp Don't bother if you don't have a 93+ manual handy.
B) If you set the car to 66 degrees on a reasonably warm but not scorching day, and just let it sit does it actually get to 66 inside the car given enough time? (mine doesn't)
C) If you set the car to max cold, recirculate, and max fan manually how cold does it get at the vent? Mine got to about 50F, which does not seem cold enough given the posts I have seen with upper 30s and R12. Is it my system, the different coolant, or...?
D) Anything else I might have overlooked or if I am just being too picky?)

Hopefully this will not take some kind soul more than about 10 mins. Thank you for any help you can provide.

Mark

Edit, as a nice little side note, you can look up list prices for parts, by part number HERE . I did not know that, and it is downright handy.

 

[MJK]

C'mon guys, nobody has been through this before? Even if I am first, somebody out there has got to be willing to unplug this and tell me if yours acts a little nutty like mine does. It'll take 5 mins, TOPS.

Pretty Please?

 

[jlindy]

I am interested in hearing this as well because mine acts in a similar fashion, but not as bad. When I go through all the modes, each mode works fine. When on 60 it is really cold, but 61-69 seem to be all the same temp (at least fan speed) if I am not mistaken. Also, when I have it in the auto mode it doesn't adjust the fan speed, only the temp a little. On 60 in auto, fan goes all the way high as it should, but switch it to 61 and the fan just trickles out. My temp sensor seems to be not telling the system when to work harder to get the car warmer or cooler, but it looks to be working.

I usually use the temp control as a manual set up adjusting the fan speed myself.

 

[Cees-Jan]

I know that all Honda airco are designed to cool down the air 15 degrees celcius (sorry, I dont know it in F).This can be measured in the following way:

Open both doors
start the car and airco (DUH)
Switch highest fan speed (manually)
Switch to recirculation
Switch to upper dash vents
Measure temperature at the suction of the air (Passengr side below)
Measure temp of the air out of the vent.

Temp difference should be 15 Celcius

I myself have this problem too ,only with a Legend, temperature on a hot sunny day not the temp shown on the display.....In winter I need to set 25 Celcius to obtain 20 Celcius (too cold )

 

[nsxtasy]

I know that all Honda airco are designed to cool down the air 15 degrees celcius (sorry, I dont know it in F).

A difference of 15 degrees C is the same thing as a difference of 27 degrees F.

 

[DutchBlackNsx]

Is the blower working at max speed, at slowest speed, AND anything in between ?
Often reported failure with the blowermotor.

Also check if same temp i commin out af all vents at the different modes.

I myself have R134a in my system (i mean the car.... doh), which was a R12 before.
I have no trouble with the climate control, i also wouldn't think that the R134a would give a problem, as the climatecontrol regulates the temp, by measuring, and then adjusting, so if the R134a would give less cooling, the climatecontrol would just cool a little longer.
But then, its a NSX, and you never know.


Mich

 

[MJK]

Thanks for the responses guys.

The fan works on all modes, and the A/C system is fully charaged. R134a came standard on the car, it is not an R12 to R134a conversion. THe blower motor and control box are good.

The only problem the system has is when I try to operate it in 'full auto' mode. It almost HAS to be the inside or outside temperature sensor. Inside seems more logical, but looks/tests fine. The outside one is not obviously bad, but is a little more dubious. I found it desconnected, and reconnected it with little effect.

I am looking for some validation that this is the problem before I go off ordering new stuff.

Can someone disconnect thiers and see if your A/C system acts similarly? Here is what I HOPE someone can tell me.

Connected/Good outside temp sensor:
"Full auto" set at any temp inside the car gets and keeps the car at that temp'.

Disconnected outside temp sensor:
All manual controls work fine, but on 'full auto' the car does not keep the proper inside temperature.

This should be really easy for someone to do, there is a quick disonnect clip right behing the center crossmember on the bumper. Right here:

 

[jlindy]

Thanks for the responses guys.

The fan works on all modes, and the A/C system is fully charaged. R134a came standard on the car, it is not an R12 to R134a conversion. THe blower motor and control box are good.

The only problem the system has is when I try to operate it in 'full auto' mode. It almost HAS to be the inside or outside temperature sensor. Inside seems more logical, but looks/tests fine. The outside one is not obviously bad, but is a little more dubious. I found it desconnected, and reconnected it with little effect.

I am looking for some validation that this is the problem before I go off ordering new stuff.

Can someone disconnect thiers and see if your A/C system acts similarly? Here is what I HOPE someone can tell me.

Connected/Good outside temp sensor:
"Full auto" set at any temp inside the car gets and keeps the car at that temp'.

Disconnected outside temp sensor:
All manual controls work fine, but on 'full auto' the car does not keep the proper inside temperature.

This should be really easy for someone to do, there is a quick disonnect clip right behing the center crossmember on the bumper. Right here:

What does the outside sensor look like? Since I am having the same problem, I looked up in the front bumper and didn't see what looked like to be a sensor. I saw two circular discs, one on each side behind the front bumper. On the right one, I saw a wire coming out of it that had a plug on the end that was not going to anything. I didn't see anything for it to plug into either. So if WhiteNSX is right, then maybe I don't have that outside sensor to keep the climate control at a constant temp inside the vehicle. Please advise.

 

[MJK]

Like this:

 

[steveny]

The symptom you are having is one of the many symptoms I was having with my C/C. I was told by the Acura service tech that inside the duct work in the dash are doors which open to mix the air to the desired temperature and that my doors were not functioning properly and needed to be replaced. I am not even sure if such doors exist and if this is even good advice???

 

[MJK]

Check out the self diagnostics mode, and you can determine the answer to that one yourself.

 

[MJK]

I'd run this one too:

 

[jlindy]

I don't see a bracket that looks like the one WhiteNSX posted, nor do I see anything that looks like a temp gauge. Do you see anything. You can see the lone red plug hanging on the right side of the screen that I believe goes into the outside temp sensor.

 

[MJK]

Mine was mounted as shown below, but was disconnected when I found it. Someone had obviously been there before. It is not a guage, but just a little thermocouple. I don't see yours in the pic, and that dangling connector looks the right shape for it. I can't tell where is goes from the picture, but I can say that the sensor connectors is NOT the connector that comes off the horns. Mine comes in from the angle shown in your pic, so I bet that is it.

Run through the second diagnostics page I posted and that will tell you if your outside temp sensor has been disconnected or removed (the defrost light is the one that will light up). That is how I found out that mine was disconnected. It does not tell you if it is within spec though, only if it is connected.

You'll need a DMM to tell if it is within spec. The 93 manual has a chart that correlates temperature to to resisitance for the outside temp thermocouple. The 91 (online manual) is a little vague and just gives a range that 'is good'. My sensor tests good by 91 standards, and about 10-15F off by the 93 standards.

Thanks for the help in figuring this out, hopefully someone whose temp settings work at full auto can disconnect thier outside temp sensor and fill us both in.

If it helps, I can post a pic of my sensor and the charts in the 93 manual when I get home tonight?

 

[jlindy]

Mine was mounted as shown below, but was disconnected when I found it. Someone had obviously been there before. It is not a guage, but just a little thermocouple. I don't see yours in the pic, and that dangling connector looks the right shape for it. I can't tell where is goes from the picture, but I can say that the sensor connectors is NOT the connector that comes off the horns. Mine comes in from the angle shown in your pic, so I bet that is it.

Run through the second diagnostics page I posted and that will tell you if your outside temp sensor has been disconnected or removed (the defrost light is the one that will light up). That is how I found out that mine was disconnected. It does not tell you if it is within spec though, only if it is connected.

You'll need a DMM to tell if it is within spec. The 93 manual has a chart that correlates temperature to to resisitance for the outside temp thermocouple. The 91 (online manual) is a little vague and just gives a range that 'is good'. My sensor tests good by 91 standards, and about 10-15F off by the 93 standards.

Thanks for the help in figuring this out, hopefully someone whose temp settings work at full auto can disconnect thier outside temp sensor and fill us both in.

If it helps, I can post a pic of my sensor and the charts in the 93 manual when I get home tonight?

After really getting up in there and doing the diagnostic test, I found a connector under the first tier closest to the ground that was not plugged in. My diagnostic showed that it was the ambient sensor which I assume is the one at the front of the car. I checked some modes after plugging it in and it didn't say there was a problem anymore after connecting it. I switched it from 60 degrees auto to 62 degrees auto and it seemed to adjust the fan better than before. (whereas before it didn't adjust fan speed hardly at all between temps over 60) I have only tested in my garage in the shade so I will have to try again once I am out, but it seems to work better.

When I ran the first test now and before, all my modes worked just fine so I know it isn't my vent doors not working properly.
Thanks for your help and hopefully it is fixed now.

 

[MJK]

You mnd snapping a pic of where yours is mounted?

 

[jlindy]

Well, I took it out in the sun and it wasn't much better, but just a little bit. If I rated my situation as a 1 and perfect as a 10, then by plugging in the front sensor, it upgraded to a 3. I still prefer to put it on 60 and adjust the manual myself.

As far as a picture of where it is mounted, I can't really get any better than what I took because underneath there is a shield that covers it. If you look right below your red arrow and follow the vertical painted crossbar down, you will see a yellowish/redish colored dot on the backside of the crossbar closest to the radiator. That is the bolt that the sensor is mounted with, but it goes underneath that part and not on top.

It's still not working like it should in my opinion.

 

[MJK]

Cool, I can follow where you are at in the pic now. It sounds like you and I have the same problem now on 'full auto'.

Did you use a DMM to check it out? I'll post some specs from my service manual in when I get home if you don't have the 93+ handy.

 

[MJK]

FYI, the internal sensor chart is on the left, and the ambient/outside is on the right:

 

[jlindy]

I don't really know what a DMM is or how to use it.

 

[MJK]

Ah sorry, DMM = digital multimeter. It is used to measure the electrical resistance (in ohms/omega sign), the potential (voltage/v) or current (amps/a) between 2 points in an electrical circuit.

The interior and ambient air sensors are thermocouples - which means theier electrical resistance varies with temperature per the above curves. They are simple devices, and are efficient way to measure temperatures for an electronic system.

That being said, I drove the X today and it seems to have gotten better at keeping the internal temperature. Maybe the system is learning. Let me know if yours does the same?

Cheap example of a DMM:

 

[tucsonsx]

Here is what I would like to know from anybody who wouldn't mind doing me a favor (before I go off ordering a new parts again):
A) How close to spec is your outside temp sensor? (easy to check, just unsnap and check the impedance - it right behind the center crossmember in the main opening of the front bumper). Mine is off about 10deg F @ ambient temp Don't bother if you don't have a 93+ manual handy.
B) If you set the car to 66 degrees on a reasonably warm but not scorching day, and just let it sit does it actually get to 66 inside the car given enough time? (mine doesn't)
C) If you set the car to max cold, recirculate, and max fan manually how cold does it get at the vent? Mine got to about 50F, which does not seem cold enough given the posts I have seen with upper 30s and R12. Is it my system, the different coolant, or...?
D) Anything else I might have overlooked or if I am just being too picky?)

Hopefully this will not take some kind soul more than about 10 mins. Thank you for any help you can provide.

Mark



My car is also a 94 - here is what I found - hope it does you some good

A) Ambient is 100F and the resistance was 1.2K ohms - pretty much what the chart shows

B)Getting the car to 66F is this heat and sun probably isn't going to happen, so I didn't try

C)After about 5 mins. mine was down to 44F - I quit at that point although it may have dropped more if I kept it running

D) I'd check the refrigerant charge - R134A is VERY critical about having exactly the correct fill. I always use the recirculate mode; it seems more accurate than Full Auto to me.

E) I totally concur that putting parts that don't fix the problem is a very bad feeling - I assume you do all tests twice to make sure they repeat

F) GOOD LUCK!!!

 

[MJK]

Thank you so much!

I have a brand spanking new ultimate cupholder that I would like to send you as a thank you. PM me your address if you want it?

 

[jlindy]

Thank you so much!

I have a brand spanking new ultimate cupholder that I would like to send you as a thank you. PM me your address if you want it?

What seat covers are those?

 

[MJK]

Those are OEM 97+, not mine. BUT mine look very similar and are from the orignal NW leather GB. Want some pics?