AC Quit

[Bigfish95971]

03,(corrected but the same) Tahoe with auto air and basic rear air.
AC ran on defrost all winter. Went out this week and NO cold at all. Have determined the following:
Clutch is not working.
Jumping pressure switch plug did not help. one side of was hot with 4.8v.
Static pressure was in the normal Green range just fine. NO evidence of past leaks.
I from O'reilly's that there are two ambient temp sensors if the front of the truck and one may be related to the AC working or not.
Today I also noticed that the compass an temp in the mirror went crazy today, sometimes I worked sometimes it was off, sometimes it flashed some symbols and maybe 188 something then off or correct, kept going back and forth.
Have not been able to access the clutch yet, Can I hot wire it for a test?

Is it one of these sensors the clutch or what. Is an OBDII code reader of any assistance with AC issues?

I am new here but have been on Dodge Cummins diesel forum for years and have done extensive writing there on my 99 Dodge with 766kMI on it. But do not know much about air beyond basics. 69 year old retired and full time fisherman.

Any thoughts . thanks in advance.

 

[OR VietVet]

Welcome to the forum.

Did you check the a/c relay in the under hood fuse/relay box? In all likelihood there is another relay in the box that is the same type of relay. Likely has the same numbers on the top of it. Switch them and see what happens. Pay close attention to the a/c relay when you pull it out. Is it real easy to pull out or do you have to work at it/wiggle it to get out? Easy means there is likely not a good connection at the a/c relay female connectors in the box. The exact same thing happened to my neighbor about 5 days ago. I crossed the low pressure switch and nothing happened. Had R134A in the system. When used last was blowing cold. I swapped the relays and nothing happened. Then I took the relay in the a/c slot and wiggled and twisted and the clutch activated and a/c started to blow cold. Sounds like you do have a fuse/relay problem. Even with an empty system, crossing the connector at the accumulator low pressure cycling switch, should activate the clutch if there is power. 4.8V is not enough.

 

[Bigfish95971]

I figure it was a 5 v system so4.8 should be good, I figured. Relay was tight no corrosion, switched with a known working one from from washer pump, same PN. All related fuses in both panels good, tight and clean. Can the clutch be accessed by removing the skid/brush l under front end? Can clutch be ** wired for a test? Do you know anything about those two temp senor and the corrospnding mirror reading?

 

[Bigfish95971]

After doing some more reading I find is 2 TWO ambient air temp sensors. I just replaced 1 and fixed mirror only. My understanding is that the other one behind the light is the main issue, Will have to do it tomorrow if available at store.

I also find it needs an instant programing from a scan tool. Mine don't work. Anybody near Yuba City, CA that can help. Can I do it with a cheap scan tool?

 

[nonickatall]

On the compressor there is a connector with 2 pins. I you attach there 12V your clutch will engage.

But first check if you air conditioning is engaged. You see that on the snow symbol at the control.

Most air conditions quit service when the are in lack of refrigerant.

 

[Bigfish95971]

When I turn the air on the snowflake comes on then goes off. Won't stay on. I have read several places that temp sensor is the issue, but it needs programming after replacement.

I was only 115* today so could not work a lot nit.

 

[Bigfish95971]

I know a guy on my Dodge forum that is building a Dodge in Germany, was in Ukeraine before war.

 

[nonickatall]

When I turn the air on the snowflake comes on then goes off. Won't stay on. I have read several places that temp sensor is the issue, but it needs programming after replacement.

I was only 115* today so could not work a lot nit.

That seems that the air conditioning detects an error. Are you sure that you have enough refrigerant in the system?

Again, I would apply 12 Volt to the connector at the compressor. That is the easiest check. Because then your compressor clutch engages and if you then have cool air in the car you AC is mechanical okay. Next thing is the pressure switch, next thing is the compressor relay.

Where did you read that a temperature sensor can make that problem and that it needs to be programmed? I never heard that...

I think, if the temperature sensor has a shortcut, and the air condition control decides to go in error mode, you can read that as error for sure.

So I would read the errors from the car first.

 

[Bigfish95971]

Is a basic OBDII all I need to program new sensor.? It is my understanding the bad sensor blocks Jumping the pressure switch to turn on the clutch. So I will try the clutch jump it I can get to it, Any trick to get to it?

 

[555hp]

04 Tahoe with auto air and basic rear air.
AC ran on defrost all winter. Went out this week and NO cold at all. Have determined the following:
Clutch is not working.
Jumping pressure switch plug did not help. one side of was hot with 4.8v.
Static pressure was in the normal Green range just fine. NO evidence of past leaks.
I from O'reilly's that there are two ambient temp sensors if the front of the truck and one may be related to the AC working or not.
Today I also noticed that the compass an temp in the mirror went crazy today, sometimes I worked sometimes it was off, sometimes it flashed some symbols and maybe 188 something then off or correct, kept going back and forth.
Have not been able to access the clutch yet, Can I hot wire it for a test?

Is it one of these sensors the clutch or what. Is an OBDII code reader of any assistance with AC issues?

I am new here but have been on Dodge Cummins diesel forum for years and have done extensive writing there on my 99 Dodge with 766kMI on it. But do not know much about air beyond basics. 69 year old retired and full time fisherman.

Any thoughts . thanks in advance.

Compass mirror temp jumping is likely due to bad solder joints in the mirror (mine were at the connector, pretty common). You need to read the real pressures on the low and high side to diagnose the AC. Given that age, you likely need a recharge (and possibly a new compressor if >200k). I have a 2003 and topped off the AC twice in its lifetime.At 155k miles, the compressor is starting to get tired (AZ heat) but still works.

 

[555hp]

Also, since you clutch is not working, you need to make sure you are jumping the low side switch (the high side is the one next to thee condensor). FYI, a low charge normally allows the compressor to kick on for two seconds before the low side switch shuts it off.

 

[nonickatall]

Is a basic OBDII all I need to program new sensor.? It is my understanding the bad sensor blocks Jumping the pressure switch to turn on the clutch. So I will try the clutch jump it I can get to it, Any trick to get to it?

I never heard that. There is a pressure switch at the coal dryer, That switch is not programmable and it's only sense is to make sure that the compressor is only engaged, when there is enough refrigerant, to prevent the compressor from damage.

Earlier you wrote something about a programmable temperature sensor. Where do you have that information from?

And again. Do logical research. Measure the pressure switch. It must be open, when there is enough refrigerant. Measure if at the compressor is 12v when ac is on. If not bring 12v on the connector and look if it's start to get cool. If not you are in lack of refrigerant.

Post the results that we can continue to look for the problem.

 

[Bigfish95971]

There is no high and low without the compressor running. I tried putting in some fluid but the pressure on my little gauge jumped to the red with very little, again without the compressor running.
Finally found the plug to the clutch, had to come in out of the heat for a bit. Will back out and check with voltmeter and jump it soon.
Not quite 100 yet but will be soon

 

[nonickatall]

There is no high and low without the compressor running. I tried putting in some fluid but the pressure on my little gauge jumped to the red with very little, again without the compressor running.
Finally found the plug to the clutch, had to come in out of the heat for a bit. Will back out and check with voltmeter and jump it soon.
Not quite 100 yet but will be soon

I don't know if this is the right way to get an air conditioner under control. An air conditioning system is not really complex, but it requires precise work. Alonger vacuum must be drawn if the system was leaking, so that any moisture is evacuated from the system. It must be checked whether the system is tight and it must be filled with the right amount of oil and the right amount of coolant so that it can function.

From my experience, this is only possible with an appropriate air conditioning service unit, which I own.

With all these do-it-yourself things and then somehow fill in a bit of liquid, I don't think much of that unless you really know what you're doing.

Don't get me wrong this is my just my experience..

 

[Bigfish95971]

Update, HELP? Mirror temp is fine after new sensor. Changed other HVAC air temp sensor, did update by removing fuse, updated fine.

Took it to a shop diagnosis, they said it was way low and filled it and did not turn on clutch yet. i jumped clutch prior and the solenoid worked the clutch.

The scanned it and it said no communication between the AC control unit and the PCM, and said it needed the control unit.

Bought used one from same Cadilac or Tahoe. Installed no change. Still no signal to the clutch.

So PCM, Wires Plug, something else?
Thoughts, ideas, have same issue?

 

[Bigfish95971]

Can you jump the compressor clutch wire somewhere up top or do you have to unplug it to get to it?
Maybe at the relay or is there another switch in line somewhere?

 

[Bigfish95971]

So nobody has had same problem?

 

[OR VietVet]

So nobody has had same problem?

Sometimes you have to refresh the post to bring it back around, like you just did.

 

[Bigfish95971]

I am surprised considring how many mmillions of Chevy/GM trucks there are out there. The Dodge Cummins Diesel forum where I am one of the major contributors. I think I will repost it in a Chevy truck forum.

 

[OR VietVet]

Out of 18 total responses by you and three others here, you had suggestions on threads #2, #5, #8, #10, #12 and #14. Some of us asked repeated questions with no responses back about some of the suggestions. Then your patience wears thin. Sometimes I see people needing help and the chronological order of events is not there and then suggestions are made and if the attempt was made at all to see if the suggestion helped or not and no responses about them. I am old enough that I just get lost in it. I know that one of us asked about the pressures in the system and all you responded about was a gauge on the suicide charge cans you get at the parts store. In short...I give up. I do hope you get it figured but I am not the one to keep trying.