This time the Air conditioning (AC)is acting squirelly

[heyjewel]

Had the compressor and the rec/drier replaced yesterday. They also replaced a relay cause they said compressor not receiving power. Compressor leaking badly. Drove out and air was not very cold. Soon became like the heater was on. Called shop and brought it right back. By the time I got there <10mins the air was as cold as I've eve felt it. They put therm in vent and it got down to 48 degrees. They poked around a bit and added 4 more ounces? of freon saying they thought they had filled it. I left and it worked as designed all the way home (1 hour) Driving it today and at engine startup it seems random as to AC starting properly. Sometimes warm, sometimes ice cold. I can seem to control it by shutting off the HVAC on the dash waiting a few seconds then turning on and it will almost always kick start the AC. On two occasions I had to do this twice.
I'm thinking something is sticking. A blend door (where would that be to cause this?) or a relay in the (brand new) DCCV? Or the relay they replaced yesterday? Any ideas.

 

[joegr]

Please, there is no air temperature blend door in the LS.
Yes, it could be the DCCV. (There are no relays in it, there are two solenoid valves.)

Let's try a wild guess here. On the drivers side of the air box, there are two temperature sensors. Both are white, and both have a two wire connector plugged into them. One is slightly below carpet level. The other is higher. You have to get under the driver's side of the dash to get to it. I think that the 1st gen has a trim panel over the pedals that you have to remove. Unplug the connector to that higher sensor. Now, see if it works consistently after that. If it does, then you'll need to replace that sensor (otherwise the evaporator will freeze over in cool weather). It's a $20 part.

I throw this out there just because the one in my 04 failed about a year ago, and the one in my 06 is failing now. The failure in the 04 kept the AC from cooling much. The failure in my 06 is doing almost exactly what you describe.

This is the part, but you will only see the rectangular part of it. The rest of it is stuck into the air box.

 

[heyjewel]

Please, there is no air temperature blend door in the LS.
Yes, it could be the DCCV. (There are no relays in it, there are two solenoid valves.)

Let's try a wild guess here. On the drivers side of the air box, there are two temperature sensors. Both are white, and both have a two wire connector plugged into them. One is slightly below carpet level. The other is higher. You have to get under the driver's side of the dash to get to it. I think that the 1st gen has a trim panel over the pedals that you have to remove. Unplug the connector to that higher sensor. Now, see if it works consistently after that. If it does, then you'll need to replace that sensor (otherwise the evaporator will freeze over in cool weather). It's a $20 part.



I throw this out there just because the one in my 04 failed about a year ago, and the one in my 06 is failing now. The failure in the 04 kept the AC from cooling much. The failure in my 06 is doing almost exactly what you describe.

This is the part, but you will only see the rectangular part of it. The rest of it is stuck into the air box.
View attachment 828570212

Wow. Great tip joegr. I found the sensor in the DVD. It's called the "Air Discharge Temperature Sensor". I'm betting you've ID'd the problem. I can't really get to it until my knees heal up. Til then I'll live with intermittent operation (working fine today) and smile cause i know how to fix it when time comes.
Oh and I was just tossing out something the tech said in regard to the blend door. I knew there wasn't one for this. Ahem...

 

[112 LS]

My reaction when someone asks joegr about the LS blend door

 

[heyjewel]

Please, there is no air temperature blend door in the LS.
Yes, it could be the DCCV. (There are no relays in it, there are two solenoid valves.)

Let's try a wild guess here. On the drivers side of the air box, there are two temperature sensors. Both are white, and both have a two wire connector plugged into them. One is slightly below carpet level. The other is higher. You have to get under the driver's side of the dash to get to it. I think that the 1st gen has a trim panel over the pedals that you have to remove. Unplug the connector to that higher sensor. Now, see if it works consistently after that. If it does, then you'll need to replace that sensor (otherwise the evaporator will freeze over in cool weather). It's a $20 part.

I throw this out there just because the one in my 04 failed about a year ago, and the one in my 06 is failing now. The failure in the 04 kept the AC from cooling much. The failure in my 06 is doing almost exactly what you describe.

This is the part, but you will only see the rectangular part of it. The rest of it is stuck into the air box.
View attachment 828570212

I've been busy replacing the clockspring in this car. Drove it more over weekend and found AC does not work almost 100% of the time now. So I am going to look for these sensors and do what you describe. I do have a question though - DVD says there's 2 of these sensors that you describe above, one on LH and one on RH. Why would failure of 1 cause the whole AC to fail?
While replacing the clockspring I noticed there is a cabin air temp sensor in the dash. I suppose this could be causing problem as well? Anticipating question - No I dont think I damaged it in any way. In fact I didnt take it out at all.

 

[joegr]

;;;DVD says there's 2 of these sensors that you describe above, one on LH and one on RH...

There are three of them. The two you are talking about are the discharge temperature sensors. They can cause problems, especially with wrong temperature air on one side or the other. However, they won't cause no cooling with the temperature set at minimum. Also, they don't seem to fail there as much.

The third one, the one I am talking about is the evaporator temperature sensor. It can shut down the AC compressor regardless of what you have the temperature set to. Also, it may fail more because it is in a more extreme environment. It's a little higher up on the air box on the driver's side.

... I noticed there is a cabin air temp sensor in the dash. I suppose this could be causing problem as well? ...

Yes, it can cause problems, but if you have the temperature set to minimum or maximum, it is removed from the picture. If it works fine at the minimum setting (you get cold air out) and at the maximum setting (you get hot air out), but not at the between settings, then the interior air temperature sensor would be a good suspect.

 

[heyjewel]

There are three of them. The two you are talking about are the discharge temperature sensors. They can cause problems, especially with wrong temperature air on one side or the other. However, they won't cause no cooling with the temperature set at minimum. Also, they don't seem to fail there as much.

The third one, the one I am talking about is the evaporator temperature sensor. It can shut down the AC compressor regardless of what you have the temperature set to. Also, it may fail more because it is in a more extreme environment. It's a little higher up on the air box on the driver's side.




Yes, it can cause problems, but if you have the temperature set to minimum or maximum, it is removed from the picture. If it works fine at the minimum setting (you get cold air out) and at the maximum setting (you get hot air out), but not at the between settings, then the interior air temperature sensor would be a good suspect.

*****************************************************
Well I did what you suggested. Had to take off lower dash panel and two plastic pieces above that then I could sorta get to the white sensor. Was able to push the connector out with a screwdriver on the release tab. Fired up the engine and WOW cold air! Really cold. Shut it down and went to house and got a thermometer. Put that in the vent and fired it back up but the air was not cold this time. Only got down to 70 degrees which was about ambient. Then I set the temp control up to 90 and watched the therm rise quickly to over 100. Then set it back down to 60 and the temp dropped rapidly down to 40!
So the jury is still out on a bad sensor but something good happened by doing this. I'm going to drive it this afternoon and see if i can get the AC to work by pumping up the temp then bringing it back down.

Now I gotta try to see if my 2007 Navigator has one of these deals too. It did basically the same squirrely stuff and now it is just hot air too! 2 nice Lincolns in my stable and the only vehicle with working AC right now is a 2000 ranger with almost quarter million miles.

 

[heyjewel]

joegr;
Did some more reading in here on this topic and found places where it is said that removing the dash might be necessary to replace the evap sensor? Ugh. Say it aint so. The sensor I got to yesterday was the only one I could see. It was a couple inches above the outlet for the HVAC on drivers side. I'm suspecting now that may not be the evap sensor? I dont see the evap sensor in the DVD. It must be way up there. I'll look again today.

 

[joegr]

Nope. No need to remove the dash. You probably have the correct one. The outlet sensors are down at/below carpet level. If you look on the passenger side at the same height as the sensor you got to on the driver's side and don't find a matching sensor there, then it was the correct one.

 

[heyjewel]

Nope. No need to remove the dash. You probably have the correct one. The outlet sensors are down at/below carpet level. If you look on the passenger side at the same height as the sensor you got to on the driver's side and don't find a matching sensor there, then it was the correct one.

I hope so. Only reference I can find in the DVD to this sensor is on this diagram as #1: As can be seen it shows the thing waaay up

at the center vent level. The other two, 7 and 10, are much lower down at radio or HVAC control level.
I did look on drivers side again and the one I found looks to be #10 as it is appx at the level of the radio/HVAC controls. I stuck my head in as far as I could and I think I saw another one maybe 6 inches further up and a couple inches closer to the firewall. I'm thinking now that is the one I want. It's going to be really hard to get to but I gotta try.

 

[heyjewel]

Nope. No need to remove the dash. You probably have the correct one. The outlet sensors are down at/below carpet level. If you look on the passenger side at the same height as the sensor you got to on the driver's side and don't find a matching sensor there, then it was the correct one.

joegr;
Replaced that sensor today. It is way up but still fairly easy to reach once u squeeze into position. As u said, no need to remove the dash, thank you very much. Tho I may soon remove the IP as the cruise lamp doesn't work.
Sadly it did not fix the problem. Same squirelly stuff - sometimes blows cold, sometimes ambient or above at startup. If it doesn't blow cold I am able to get it to do so by doing one or more auto/off cycles. So something else is intermittent in the 'turn on the compressor' logic.

 

[heyjewel]

joegr;
Replaced that sensor today. It is way up but still fairly easy to reach once u squeeze into position. As u said, no need to remove the dash, thank you very much. Tho I may soon remove the IP as the cruise lamp doesn't work.
Sadly it did not fix the problem. Same squirelly stuff - sometimes blows cold, sometimes ambient or above at startup. If it doesn't blow cold I am able to get it to do so by doing one or more auto/off cycles. So something else is intermittent in the 'turn on the compressor' logic.

Update. After driving car for week or more since I replaced the evap temp sensor I think it may actually have fixed my problem almost completely. What's happening now is the A/C starts at start-up most of the time, say >80%. When it does not start cold I have learned that if I let it run and drive the car it always turns cold after a minute or two. I never let it run like this before the new evap sensor rather I switched it on and off until it went cold. If anything changes I will update again. As for now, thanks as always to joegr.