I have already replied to another post about the "mystery connector" and gotten a lot of good information already but I still have not resolved this issue and would like to open it to anyone who would like to contribute. I have a 2007 LS Monte 3500 flex fuel which AC shutting off randomly or it sometimes won't start. When I press the AC control the compressor at times does not engage. I get the 3 blinking lights indicating no compressor and at the same time I get a message in the DIC saying ICE POSSIBLE DRIVE WITH CARE (at 85 degrees). I find it telling that this message ALWAYS comes on when the compressor shuts off during driving or if I start the car and it doesn't kick on. It definitely coincides with the compressor going off. Also if I drive the car for a while it will randomly come back on. I have also let the car sit for a few hours and it came back on. The AC has worked flawlessly for a week now but it seems to always return. I did try to ad Freon first and this had no effect on this intermittent problem. Although I have not put a gauge on it. So for all of you who are thinking OAT (outside air temp sensor) sensor I don't have one. I found the connector for this sensor and it was just hanging in the breeze (see mystery connector thread). From many posts I read this would be the logical answer (in my opinion). If anyone wants to take a shot at diagnosis I am all ears... Oh and I did order the OAT sensor which I will be putting in soon.

 

I assume your "mystery connector" is in the location below?




Based on the info in "2007 - Air Temperature Description and Operation", if that sensor above is what you are missing, replacing that sensor should correct your ICE warning on the DIC.
Also, in the same document, it states "The ambient air temperature is above 4°C (40°F)". From the best I can find, this is the reading from the same sensor seen in the screenshot highlighted in yellow. If that sensor is missing, when the car attempts to check for that reading and because it's missing it now reads the lowest temp possible, it will dis-engage the AC compressor.



As for your freon, how did you attempt to add freon without a gauge? Only ways I know are using the AC manifold gauge set (which I don't know how to operate) or the auto parts stores sell cans with those gauges on them (just follow the instructions).


At this moment, I believe the best thing to do is replace that sensor (which you have it on it's way) and then let us know if this resolved the issue or not.

 

@The_Maniac thanks for all your info and the pics they are different from what I had and seem more accurate. That is the location of the sensor I am referring to. I took off the plastic above the grill and both headlights searching sensors and that one was the only one in the area besides what looked to be 2 air bag sensors. The documents are great also and I keep re-reading them. The strangest thing in all this to me is that if the sensor doesn't exist to begin with how could it be part of the equation? Never the less I am going to put it in once I get it (in a few days). I agree I should have used a gauge to add Freon but just followed the instructions on the can and put about half in. When I attached it to the low side more probably came out then went it (seemed like a lot of pressure already). I actually did this only to humor my dad who is convinced this was all a Freon issue. My problem with that diagnosis is the AC works fine now so if it were low on Freon wouldn't it stay low on Freon and not work again? Eventually it would stop all together and not come back on if there was a leak but it has been working fine now for 2 weeks. tAs of now I am still awaiting the sensor and the AC is working great which I am very thankful for since we are setting heat records here in the NE! I will definitely post an update once I put in the sensor. Thanks again

 

I completely agree, but if it's missing, somewhere and somehow it was removed.






I completely understand where your dad is coming from. The compressor will not engage if there is not enough freon in the system. It's a safety. I am not an A/C expert, but this is the first time I heard of the A/C being linked to the outside ambient temp sensor. For example, the 00-05 Monte has a spot for an outside ambient temp sensor. If you car does not have the DIC option, you don't have the sensor, but the connector is there and the A/C works fine. I added a DIC to my '04 and I know all of that to be true.


There is a mis-understanding that people believe it is normal to re-charge the freon in your A/C system. This is 100% false. Freon does not age or loose strength as it ages or get "consumed". If you need to recharge the system, you have a freon leak, period. It can be a small leak or a big leak, but you have a leak. A good comparison I give people: how often do you recharge the freon in you refrigerator or your home's central air? Odds are if you ever do it is because the system was serviced (such as replacing a compressor) or it is now failed. These systems work near identical to the A/C in your car.


If you had freon pressure, odds are you are good on freon.




I read and found something of interest in the info I sent you.

Right now, not having the sensor, the circuit is open. Looking at the connector, it should have a 2 wire connector.
1 - Color L-GN/BK - Ambient Air Temperature Sensor Signal
2 - Color YE - Low Reference


So.... in order to see if this sensor is related as suspected, you should be able to fool the car to giving a very HOT reading. Using a paper clip and a wire, you can use the paper clip to connect to the Light Green/Black wire, tie the wire to the paper clip (if you are able to solder, then solder the wire).... I would cover the paper clip with electrical tape so only the part acting as a pin, going into the connector makes contact. Another words, make sure it cannot touch anything else anywhere.
Take the other end of the wire to a ground. Best grounds are unpainted bolts or other existing ground locations or direct to the negative battery terminal. Once successfully grounded, the car should now report 186 *F (uhm, pretty darn hot). You should no longer have the ice warning AND if this is related, the AC should activate.


This is all assuming my understanding is correct. I give the warning, I take no responsibility if you try this and something bad happens. I also would not advise driving with it staying like this. Use it only for a quick diagnostic.

 

@ the Maniac thanks for your reply and advise I completely agree with what you said on the Freon situation if there is a leak then Freon doesn't come back on its own but having a gauge sure would be nice! As for the short to ground test you suggested I think I will try the new sensor first and see how that goes (still waiting for it). But I think you are right if I did that test it should tell me if it was involved. I had another idea that might be less dangerous I was thinking that if this does happen again (2 weeks AC still working) I will disconnect the battery and reconnect it. This should reset the PCM and sensors yes? If the AC worked after that I assume I can say its sensor related. I am nervous about intentionally shorting anything wired back to the PCM. I know it probably wouldn't hurt anything but I am definitely cautious with the electronics (and everything else). I had a related question for you... when you installed the DIC did you need to do any programming Or was it just swapping/installing parts? The reason I ask is some say the OAT sensor needs to have some programming before it will work. I'm not sure if that's true or not but we will soon find out Do you have temp and compass on yours? Thanks for your time and info

 

The 00-05 Monte vs the 06-07 Monte are different animals.


In the '00-'05 Monte, adding the DIC is plug and play if you do it right. I used info from a member BB Engineer to pull the harness and pieces I needed from the junk yard, made everything plug and play. The only "programming" needed was to calibrate the compass. You basically do a reset on it and do a very slow donut in a parking lot and done. The temp sensor plugs in and just works. For your car, the temp sensor just plugs in, no programming.

 

@The_Maniac great! I am excited at the possibility of having it show me the temp it would be a small victory even if it didn't fix the AC! I should have the sensor tomorrow and will let you know what happens. It actually arrived earlier but I had shipped it to another location. If this works I may look into adding the compass also... would love to have both happy4th!

 

PS I forgot to mention this info I found prior I don't know if it matches any info you already sent but this was what I attempted before (the reset)

To perform an instant update of the Ambient Temperature Sensor, simultaneously press and hold the Recirculation button and A/C button on the HVAC control head. It is also possible to perform the instant update by using a scan tool in the special function mode and selecting instant OST update. Within a few seconds, the Driver Information Center should display the current temperature.

If the instant update creates an accurate reading, do not replace the Ambient Temperature Sensor.
To ensure greater accuracy of the outside air temperature reading, the display is programmed to perform updates based on several parameters when the vehicle is started.

The outside air temperature sensor is located in the RH front of the engine compartment, on the radiator support near the horn assembly

Below 15 mph (20 km/h), the display will not update
Between 15-25 mph (20-30 km/h), the display will update every 5 minutes
Between 26-37 mph (31-60 km/h), the display will update every 2 minutes, 30 seconds
Above 37 mph (60 km/h), the display will update every 1 minute
If the key is cycled on and engine coolant temperature (ECT) is below 140°F (60°C), the outside temperature display will update immediately.


Ambient Temp Sensor Part Number: 25775833

 

On the 06/07 Monte, I have no idea what it takes to add the compass. As I mentioned the DIC in 00-05 is different than the 06-07.


As for the "instant update" feature, if you are missing that temp sensor, the instant update won't be able to provide you any different information, as it has no sensor to get it from.


Very curious to hear what your update is once you can install the new sensor.

 

@The_Maniac I agree on the instant update feature not making any changes if no sensor at that time I though I had it. I installed the sensor today and no temp showed up, tried to disconnect it and connect it turn car off and on. I even disconnected the battery to reset the PCM and the DIC shows no temp. From what the manual says "If your vehicle has these features, the DIC also displays the compass direction and the outside air temperature when viewing the trip and fuel information. The compass direction appears on the top right corner of the DIC display. The outside air temperature automatically appears in the
bottom right corner of the DIC display. Do I need to select something specific or does it display no matter what the selection in the DIC? I assume it should be there all the time...