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low refrigerant/ ac compressor off


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Update: I checked all fuses and they are all fine none are blown. When I ran codes I did notice a longer pause than usual between MMM ans PHN. Also the IPC U1255 is still current and a new current code ACM B1340 popped up so not sure what that one is. All lights on dash came on when I held the warmer and off buttons to start diagnostics.

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You get all the codes by going to the A/C buttons and pressing <Off> and <Pass Warmer> together for several seconds until all the dash lights come on, then releasing both buttons. This puts the car's main computer in the diagnostic mode. It interrogates each module for codes and displays them on the driver information center, one module at a time, begging with the PCM (engine), IPM (dashboard), and ACM (air conditioner). You need to do this because only a few codes cause messages on the display.

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-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Sounds like the blend door is stuck in the heat position. Before replacing the actuator, try running the temp to 90° and letting it stabilize for a couple of minutes and then run it to 60° and wait for a few minutes. Repeat the cycle a few times. Sometimes, that corrects a confused actuator.

Other times, the actuator strips one or more of the gears internally and it needs to be replaced.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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The U1255 can cause an air conditioner problem. Run the codes again and see which module(s) are throwing the U1255. Let us know and we'll look up what needs to be done to fix it. I'll type the entire section on DTC U1255 from page 1C-65 in the Automatic Control Air Conditioning section of the 1997 FSM.

If you are sure that the ACM is the module that set this code, you should red this section very carefully. From the 1997 FSM, page 1C-65:

DTC 1255

GENERAL LOSS OF SERIAL DATA COMMUNICATIONS

CIRCUIT DESCRIPTION

This DTC refers to a generic loss of serial data communication with an unknown module. This code generally will set when the vehicle is first started, and the heater and A/C programmer or CCP requests information from another module and does not get a responsive. This DTC will clear when the module with the information that the heater and A/C programmer or CCP is requesting comes back on-line.

TEST CONDITONS

1. Ignition in ON.

FAILURE CONDITONS

1. Open circuit.

ACTION TAKEN

1. Set DTC U1255.

TROUBLESHOOTING HINTS

If DTC U1255 is set each ignition cycle even though the code was cleared, the following items should be checked.

  1. Check DTCs for the IPC, PZM and PCM. If the IPC has set code DTC U1152 or if the PCM has set DTC P1605, replace the heater and tA/C programmer. If the IPC, PCM or PZM has set code DTC U1153, replace the CCP.
  2. Check the option bytes in the IPC. Make sure that the correct options have been programmed into the IPC. Refer to Computer System Diagnosis.
  3. Check that the proper heater and A/C programmer has been installed on the vehicle.

If the three checks above are OK, the heater and A/C programmer and CCP is OK. Do not replace the components. Refer to Computer System Diagnosis.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Update: I checked all fuses and they are all fine none are blown. When I ran codes I did notice a longer pause than usual between MMM ans PHN. Also the IPC U1255 is still current and a new current code ACM B1340 popped up so not sure what that one is. All lights on dash came on when I held the warmer and off buttons to start diagnostics.

There is no module between MMM and PHN in my list. I believe that holds for the Deville too for the 1997 model year. The fact that you do have a PHN module means that your car came with a phone, and probably OnStar. The pause probably means that your phone is on, and trying in vain to link up with a base station. It's not a battery drain problem but if you like you can turn the phone OFF at the handset.

The U1255 CURRENT Means that there is a serious problem, quite possibly a dead module. Which module threw the U1255? The module that throws the U1255 is the one that is trying to talk to a dead module.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Update: I cleared the codrs and was able to get compressor to click and engage to take the charge. Now when turn air on the compressor engages but then it clicks again about every 5 seconds. When I turn air off the clicking noise goes away. Did I do something wrong? Just can't figure out why it engages then clicks again about 5 seconds later and so on and so forth. Do you guys know why its doing this. It's reading 45psi on the gauge

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45 on the low side? . That may be a little high. pull codes again. If the system is overcharged it will disable the compressor to prevent damage.

If it is still low it will turn on and drop pressure too low and cycle back off, it will continue to do this til you have sufficient charge in the system, then it should stay on steadily and go off once in awhile.

You should have 2 readings on the low side. When the compressor is off the pressure should be higher, when the compressor is on it should be lower

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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What should the psi show if compressor is off? What should the psi show if compressor is on? Right now it shows 45psi so the compressor is off is this correct? Ehen it's on what should the psi be reading at? And also I could hear the compressor clickong about every 4 seconds what does this mean? Thanks for the quick response.

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Is the compressor cycling every 4 seconds? If so, that could indicate a low charge but you said you had 2.0 lbs. in the system. Did you evacuate the system with a vacuum pump prior to charging with refrigerant?

What does the high side pressure read? That would be very helpful in diagnosing the problem.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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if it is reading 45 psi off that sounds ok. It should be around 35- 40 when running,

Rule of thumb with with high side is it should be 1.5 times the ambient temp. So basically on a 608 day the high side pressure should be about 150 when on

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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If the static pressure is only 45 psi, the system is very low on refrigerant... Static pressure should be around 100psi.

The high side reading is needed to diagnose the system. If one of those "low side only" gages is being used, it is worse than worthless...

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Update: I took the caddy back to the same place today and told them that they had only put 1lb of r134a in it and my system requires 2lbs. So he vacuumed the system out. I cranked the car and ran diagnostics cleared codes then he started to charge the system. Again he said it would only take 1lb. So I turned the air on max cool bc he forgot to and then 2 seconds later he said it's taking the charge now and put 2lbs in it. Finally it started blowing snowball. Ok so I left there and drove to my gf's house whice was a 30 min drive from where I was and half way there it stopped blowing cold again. Wtf I'm so pissed off man I can't believe this. What do I do now? Plz help!

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Guess something is clogged up, when I switch from heat to air I can hear it really loud back behind the glove box. It's almost like a vacuum hose or something like the doors closing ti heater and opening to ac.

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There are multiple air control doors on your car. Only one of them has to be bad to keep it from blowing cool air.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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With the engine running and the air conditioning ON, open the hood and feel the accumulator (the large can on the passenger side of the engine compartment with the low side port). Is it cold? If yes, the problem is an actuator. If no, there is a large leak i the system.

My guess is there is an issue with one of the actuators since you heard abnormal noises behind the glove box.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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The large silver can that is attached to the overflow tank that says R137A on it? I don't think it was hot last time I did that but will be sure to check again. I heard replacing those acuators behind the glove box is a fairly easy fix, is this true and if so how to you go about getting to it?

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If you still have a U1255 CURRENT, there could be a connector problem with the air conditioning controller, which is under the dash on the passenger side, and controls all the actuators.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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I think the first thing to do is the easy thing, the one that KHE suggested just now, check the big silver accumulator tank under the hood on the passenger side next to the surge tank while the A/C is running. If it's cold, the A/C is cooling. If it's not, the A/C is not cooling.

My personal black hole is determining which module is throwing the U1255 CURRENT code. Please run the codes again and see which module is being interrogated when the U1255 CURRENT message comes up.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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It should not be bad to get to. It is easy to remove the glove compartment and the lower kick panel. There is a writeup for it. I have done them on both dual zone and regular climate controls and have had no problems.

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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It depends on where the leak is. Usually a leak in a car A/C system is repaired by replacing the leaking component, but sometimes it's as simple as replacing an O-ring or even tightening a fitting. Where is the leak? Can you tell exactly?

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Ok its on the low port just down past the silver accumulater where the fitting is at the end where the high port begins if that makes sense. You have the low port running up and down then the high port running left to right. When the ac is running you can clearly feel the freonleaking out from under that fitting like it's not tightened down enough or also like you said it could be the oring on that fitting.

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I would start by tightening the fitting, then using a sniffer to see if it's still leaking.

Whenever any A/C system needs work, the first thing to do if it has any Freon in it at all is to check for leaks. The last thing to do after working on an A/C system is to check for leaks. Whoever charged system should be able to fix this in a few minutes. When he is done, ask him to check for leaks. He should have a hand tool with a gooseneck probe like one of these on Amazon:

http://www.amazon.com/s/?ie=UTF8&keywords=leak+detector+refrigerant

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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