AC Clutch stays engaged

[IceCold]

Man it's hot out here......I was checking my ac out and I noticed that my ac clutch stays engaged without cycling on & off. I put my gauges on and the low side runs at 40, and the high side sits at 220 without moving. When I first turn the ac on, the passenger side gets cold immediately and the drivers side take an extra mile for the temperature to match cold on both sides. I thought I might be a bit low on 134a (freon) but that's not the case. I put a new actuator in for drivers side and pulled the fuse and negative battery post so it could reset after I installed it. I also had to redo the ground wire running from ABS Pump to grounding bolt, so I think that's the reason for some of the history codes My traction Control stays engaged all the time. Any advice would be helpful.

Current

amp u1000

imp b0429

History

amp u1128

ddr u1000

ipm b1004

lrd u1000

pcm u1000

pcm u1040

prd u1000

[Logan]

Did you actually put any freon in? This sounds like a classic case of low freon on the Devilles....warm on the drivers side.

An additional problem...your AC gauges will read perfectly normal. GM has a blurb somewhere in the electronic service manual..'is the drivers side warmer then passenger side? Do the gauges read normal? Oh..it's low on freon.'

[IceCold]

Yes, I added oil and Freon to proper specs of 2lbs and maybe not much over. In fact the gauge was sitting a little high so I back abit out of the system. I was reading on other post that it seems some models stay running when temp is kinda hot out. 96 today. After I top it off the clutch was cycling like it should just didn't do it today. When it cools off tonight i'm gonna check it out again.

[Logan]

It does not sound like low freon is the problem. The warmer drivers side is a common complaint....most times a can of freon fixes it.

For future reference....I did go dig up the buried GM service manual info. This is for a 2001 Deville.

Air Conditioning (A/C) Diagnostics Pressure Zone A:

Step 2. "Does the discharge air temperture between the right and left center I/P outlets differ by 2-3 degrees?" (If Yes..go to step 7)

Step 7. The A/C system is undercharged but not enough to show a difference in low or high side pressures."

Umm duh...I wish I knew that before taking some of my dash apart. Anyway....as for the 2-3 degress difference....more like 10-15 degress difference is common.

[IceCold]

I put my gauges on it again and the low side is sitting in the blue zone right before the yellow danger and the high side is sitting right at 220 not moving, but I know it should be cycling. Maybe I got some air in the line and I didn't vacuum it down enough...It's to hot to burn up the compressor, so maybe a shop can drain it, then run another vacuum and put my freon back. I thought at one time I may have too much in...Thanks for your response.

[KHE]

A/C systems are not a tire... The only way to know if it is low on refrigerant is to recover and weigh the charge. Going by pressures is not that accurate - it is a troubleshooting tool but that's about it.

[rockfangd]

Well on a 90* day low side should seem to be around 38-40. High side should be around 220. Which yours seem to be. Maybe it needs to be vacummed and recharged

[IceCold]

Agree, That's next on the agenda. Thanks for all replies

[Cadillac Jim]

You have a ton of network codes. Something is shorting out the PPL wire in your wiring harness and bringing down the network. That can cause your problem.

[IceCold]

I was getting ready to post on that.....I just drove to the store and my battery light came on, then the security light, and to top it off, the locks started popping up and down. I opened the hood, closed it and drove back to the house and checked codes and got a ton of them but all history.

DDM U1000, DDS U1000, DIM U1000, IPC U1000,IPM U1000 ,LPR U1000, PCM U1000, PCM U1064, PDM U1000, RFA U1000,RRD U1000, SDM U1000, and no VTD codes.

yesterday I noticed my fuse box got extremely hot, then the battery and security light came on, and to top it off my car amp in my truck gets very hot but the trunk is hot so I can expect heat on heat, but I planned on hooking external fans on the amp to compensate for air restriction.

You think my ECM going or gone bad?

[KHE]

You think my ECM going or gone bad?

Not likely - The ECM is a very rugged/durable unit. Something tells me your aftermarket stereo equipment is causing some issues with the electrical system in the car.

[IceCold]

Interesting concept. I was just thinking that each time something happened I had my stereo powered off. All of this didn't happen until I started checking out my ac, and the stereo was off. I was thinking on one code says (no irc data) which represents my radio communication to the main ecm being off line. It shouldn't make a difference if the radio was on or off because all was fine until ac issue came up. If it's not my radio, what else would you look for causing this problem. All my grounds are tight and battery charging good with correct amps. Maybe a fuse or relay bad, I'm kinda lost at this point, but to eliminate the radio of or on i'm gonna let it run and do a test drive with the unit on and see what happens. Yesterday I had more codes than this....Thanks for your reply..

[Cadillac Jim]

Don't worry about the weather making built-in electronics too hot. The electronics industry has a special category for temperature range for automotive electronics. It's a wider temperature range than for consumer electronics but not as wide as the military temperature ranges.

[Cadillac Jim]

I looked at the 2005 FSM and found a description of how the A/C system works. Once the A/C clutch is engaged, it disengages only when:

• Compressor thermal switch is opened (compressor temperature goes over 125°C or 257°F)
• Throttle position is 100%
• A/C Pressure is more than 2850 kPa (413 psi)
• A/C Pressure is less than 204 kPa (30 psi)
• Engine coolant temperature (ECT) is more than 128°C (262°F)

In other words, it won't cycle normally. If you aren't using your A/C cooling because the weather is too cool or whatever, or if the system is overcharged, the pressure on the high side can go over 413 psi and it will cycle then. But not normally.

Other notes of interest:

• The A/C clutch is operated by the PCM. The IPM (which apparently absorbs the ACM functions in this model) send requests for the A/C clutch to the PCM over the car's network. If the network is down, as all your Unnnn codes show, the A/C clutch won't engage. If the network goes down, the A/C clutch will release.
• The voltage on the IPM must be between 9 Volts and 16 Volts. If farkled wiring, bad battery cables, or a low or bad battery drop your battery voltage below 9 Volts, the A/C clutch will release.
• At WOT the A/C clutch disengages.

[IceCold]

I thank you very much once again for your input and expertise in this matter. How can I trace and find the PPL wires? Going to verify cables and wires later this evening when it cools off abit. Do you think my driver side actuator maybe sticking? You can see it's bothering me like a fly buzzing around your head. Fuse or relay? Did a actuator relearn and same thing. Hate to sound if i'm repeating myself. Thanks Again

[KHE]

I would disconnect any aftermarket electronics and see if the symptoms go away. If they do, the issue is with the add-on electronics.

[Cadillac Jim]

I looked at all your U1000 and the single U1064 code and these are the codes that are thrown when the network is shorted to ground. The IPM can't talk to anything. On older cars, you sometimes got a "NO PCM DATA" message for loss of all network link to a module. The only mystery is that I don't know what a "LPR" module is in a 2005 Deville.

All of the modules that the IPM/DIM reported as having U1000 codes are connected to central bus points S300 and S304, which includes the radio. In other words, it looks like a pin on the connector to the aftermarket radio is shorted to ground, battery, or something, and it brought down the whole network. There is a small part of the network that is separate from S300 and S304, between the IPC and PCM, plus the DLC.

What was happening was the entire car's network was down. When this fault occurs, your car will continue to run for safety reasons but nothing will work unless it has its own dedicated network line, like the ABS. The S300-S304 node is talked to by the EBCM (electronic brake control module) which talks to the PCM, which talks to the IPM over the same network line as the DLC - and one of the CD playback options.

I think that KHE has very good advice, since there are hooks to the CD playback even on the dedicated PCM network line.

[IceCold]

OK.....Disconnected the battery negative this morning, then removed the radio and put the stock radio back in.

BTW: the first time all these codes came up is when I was in the garage, hood up, car running adding freon and it seemed the front of the car to include the fuse panel was extremely hot. Battery light came on, then the security light came on, and finally parts of the dash went blank. "Radio Turned Off & AC ON"

The 2nd time I had the car idling in the driveway for 15 minutes, then drove to the store about 1 mile away and when I came back to start the car the battery light came back on, then the security light and turned the car off then pop the hood. Waited a few minutes then started the car all seemed fine. "Radio Turned Off & AC ON"

Came home and pulled trouble codes and listed them above and cleared codes. Last night I drove the car a few blocks with "Radio & AC On" and nothing.

Will post back after I make a few runs with the result..

[IceCold]

Caddyinfo family, if you can see my smile you will see me grinning from ear to ear show a few teeth. I read outside temp was 93 degrees and the AC chart I downloaded indicated my low side should run 50-55 and high should be 275-300. I put in 1 can of 134a and that took my low side to 53-55 and the high side went to 260-265, but the end result was my AC system is icecold again. No crazy codes after test drive. Then re installed JVC head unit and left it running and it seems to be all good. I had to replace the relay for fan 1 because I don't think my fans were running. Thank you for all your help! AC CASE CLOSED!

[Cadillac Jim]

Keep us posted on the status quo for a couple of weeks, an come back if you have another problem.

[IceCold]

Oh yeah