mike5plus5 Posted July 13, 2016 Report Share Posted July 13, 2016 About a month ago my A/C quit blowing cold. After 3 days it suddenly started working and has worked flawlessly since then until last Sunday when it suddenly quit blowing cold again. The compressor clutch engages for about 5 seconds, then disengages and won't engage again for approx. 1 minute, then repeats this cycle never staying engaged long enough to cool. It acts like maybe a stopped up orifice tube but I don't have a gauge to read the high side pressure so I don't know. Or that temperature control door (B0429) may have got stuck, again? It's been 4 days without A/C so far this time. All codes except RIM - DTC C0658 are current. IPC - DTC U1000 Class 2 Communication Malfunction IPM - DTC B0429 Temperature Control #3 Rear Circuit Range/Performance IRC - DTC U1064 Loss of Communications with DIM PCM - DTC P0422 Catalyst System Low Efficiency Bank 1 PCM - DTC P0741 TCC System Stuck Off PCM - DTC P1571 Traction Control Torque Request Circuit PCM - DTC P1860 TCC PWM Solenoid Circuit Electrical PCM - DTC U1040 Loss of Class 2 Communications with ABS RIM - DTC C0658 Level Control Compressor Circuit High (history) SDM - DTC U1000 Class 2 Communication Malfunction After start / run in park after cleared codes: IPC - DTC U1000 Class 2 Communication Malfunction / current IPM - DTC B0429 Temperature Control #3 Rear Circuit Range/Performance PCM - DTC P1571 Traction Control Torque Request Circuit PCM - DTC U1040 Loss of Class 2 Communications with ABS SDM - DTC U1000 Class 2 Communication Malfunction NOTE: (IPC - U1000, SDM - U1000 and IPM B0429 have been constant codes since I bought this car 3-19-2016 but A/C has always worked regardless) Link to comment Share on other sites More sharing options...
Bruce Nunnally Posted July 14, 2016 Report Share Posted July 14, 2016 It's the time of year for A/C posts alright. Good job posting the codes & a clear description. B0429 seem most relevant but is rear seat a/c. Bruce 2023 Cadillac CT4-V Blackwing Follow me on: Twitter Instagram Youtube Link to comment Share on other sites More sharing options...
OldCadTech Posted July 14, 2016 Report Share Posted July 14, 2016 To me it sounds like a cycling switch problem. But it could be actually low on freon. Although I would expect a code for low refrigerant to set. Not uncommon for the switches to go bad and not set a code though. You can jump the cycling switch and see if the a/c blows cold. If not, remove the cycling switch and check to see if it has oil in the connector end. That is usually the indication of leakage, so if the a/c is low on freon you would have to correct that condition first. THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!! Link to comment Share on other sites More sharing options...
BodybyFisher Posted July 14, 2016 Report Share Posted July 14, 2016 This is a new one, where is the cycling switch? Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
OldCadTech Posted July 14, 2016 Report Share Posted July 14, 2016 Cycling switch location THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!! Link to comment Share on other sites More sharing options...
OldCadTech Posted July 14, 2016 Report Share Posted July 14, 2016 Okay, my bad, I'm using OLD names / nicknames - low pressure switch THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!! Link to comment Share on other sites More sharing options...
BodybyFisher Posted July 14, 2016 Report Share Posted July 14, 2016 We recently had a discussion regarding this photo. On my 96 to at least 98, #3 is the low pressure switch, I recently changed one. Has this changed on newer models?, this is showing the lower pressure switch as #1. I think we concluded that something was wrong with this illustration. Have a look at your 98. Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
OldCadTech Posted July 14, 2016 Report Share Posted July 14, 2016 Hmm, I looked at the 02 and the 98, they are both the same but the low pressure (temp) switch #3 is near the compressor on the Seville. The Deville is different but the one they marked low pressure switch in the diagram is actually in the inlet side of the evaporator, so it is low pressure liquid. It is correct nomenclature as it is a low side pressure switch. ( after the evap core s is a low pressure gas, before the evap it is a low pressure liquid ) So in the diagram #1 is the (inlet) low pressure liquid and #3 is the low pressure gas. In the diagram #3 would be the "cycling" switch. It was a lot easier when it was mounted on the receiver/drier, or maybe that is just old age talk. THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!! Link to comment Share on other sites More sharing options...
OldCadTech Posted July 14, 2016 Report Share Posted July 14, 2016 I'm not sure I agree with the definition of #3 as a temp sensor but I'd have to re-study the switch internals. Is it a thermistor? I don't know. If the connector is jumped it should engage the compressor. ( notice the disclaimer word should ) THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!! Link to comment Share on other sites More sharing options...
OldCadTech Posted July 14, 2016 Report Share Posted July 14, 2016 After all that, it might be a relay, but first things first. THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!! Link to comment Share on other sites More sharing options...
BodybyFisher Posted July 14, 2016 Report Share Posted July 14, 2016 I believe the low pressure switch is #3. I think that photo is mislabled. I will post a link to my thread on that discussion. Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
OldCadTech Posted July 14, 2016 Report Share Posted July 14, 2016 @BodybyFisher they are both low pressure switches. they call #3 low pressure temp switch, which it probably is. Think of it as a low pressure temperature cycling switch, if the temp of the low pressure gas is too high it will demand more compressor operation, when the temp lowers enough it will cycle the compressor back off. The reason they call them both low pressure is they are in the low pressure side of the system. An A/C compressor can NOT pump liquid so the inlet side of a compressor is low pressure gas, The outlet side of the compressor and inlet side of condenser is high pressure gas, it is converted to high pressure liquid and exits the condenser as high pressure liquid, when it reaches the orifice it is still high pressure liquid the orifice converts it to a low pressure liquid.by expansion ( an orifice tube is a form of expansion valve ) it enters the evap core as a low pressure liquid and exits as a low pressure gas and back to the compressor to start the cycle all over again. Don't change the diagram, the nomenclature is correct THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!! Link to comment Share on other sites More sharing options...
OldCadTech Posted July 14, 2016 Report Share Posted July 14, 2016 ONE more thing, GM/Cadillac is monitoring the pressure of the inlet low pressure liquid at the inlet to the evap core, then they are sampling the temp of the low pressure gas as it leaves the evap core. Since the low pressure liquid is absorbing heat as it converts to low pressure gas, the BCM can monitor the performance of the evaporator as that is the cool/cold air that the driver and passengers are "feeling" . I believe the temperature reading is a more accurate and faster indication than only a pressure reading of the post evap core temperature exchange. The R-134 is "absorbing" the heat from the cabin. The cold air you feel is the direct result of the heat absorption during the conversion from liquid to gas. THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!! Link to comment Share on other sites More sharing options...
BodybyFisher Posted July 14, 2016 Report Share Posted July 14, 2016 Here is a scan I just took from the 96 FSM. You will notice that #1 is called a LOW SIDE THERMISTER, as we know, THERMISTERS measure TEMPERATURE. Now note that #13 is called a LOW PRESSURE SWITCH, this switch measures Freon PRESSURE, to protect the compressor as stated in the manual as follows. I have worked on a 96, 97, 98 and 99 and have replaced 2 LOW PRESSURE SWITCHES, that were in #13's location, one was leaking and one was stuck OFF and the compressor would not start they were BOTH behind a Schrader valve and you simply unscrew them without depressurizing the system. I was able to jump the switch terminals and start the compressor. Here is a photo of one that I replaced last month that was leaking as you can see, it was in #13's location: Here is a clear photo from the 98 Eldorado I worked on showing the #13 pressure SWITCH on the left with the blue wire retainer at the end and the #1 Low Side Thermistor or Temp Sensor at the top to the left of the orifice tube and black tape on the line: Now I am going to really confuse the situation and show a mistake in the first scan above here that I posted, I just found a mistake in my 96 manual that I never saw before today. Look at the wording at the bottom right AC Low Pressure Switch from the manual "The low side pressure switch is located on the low side refrigerant line running along the engine compartment rear bulkhead just above the evaporator case" << that statement is WRONG and it is probably the reason for all of the confusion. To cement that the statement is wrong, continue reading, "It is mounted on a Schrader valve therefore, the system does NOT have to be discharge to remove the switch". And that is my experience. I hope this clarifies my understanding and clears up what I am trying to say. If you do not believe me, UNSCREW #13, LOW PRESSURE SWITCH, blue dot in my scan and you will see the SCHRADER valve behind it. Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
KHE Posted July 14, 2016 Report Share Posted July 14, 2016 Don't jump the sensors - that is asking for additional troubles. The pressure switch (#13 in the diagram) can be jumped to test the system. What are the low and high side pressure readings? Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
BodybyFisher Posted July 14, 2016 Report Share Posted July 14, 2016 2 hours ago, KHE said: Don't jump the sensors - that is asking for additional troubles. The pressure switch (#13 in the diagram) can be jumped to test the system. What are the low and high side pressure readings? Kevin, does the pressure switch #13 act like a temp sensor also or a thermistor? I was under the impression that #13 ONLY acted as a low freon pressure switch. Thanks Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
KHE Posted July 14, 2016 Report Share Posted July 14, 2016 The pressure switch will open when the refrigerant pressure drops below a threshold. Sometimes they fail in the open position and not allow the compressor to run. The easiest way to test for that is to look at the static pressure in the system - if it is 70-90psi + and the compressor won't run, then test the pressure switch. If the system has proper static pressure, unplug the pressure sensor and check for continuity across the sensor terminals. An open would point to the pressure sensor; if the sensor has continuity, then the problem lies elsewhere. The high and low pressure sensors are the thermistors which monitor the temperature difference between the high and low sides. They tell the ACM how long to engage the compressor. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
BodybyFisher Posted July 14, 2016 Report Share Posted July 14, 2016 So let me make this clear, #13, does NOT have two functions pressure AND temp, ONLY pressure? Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
OldCadTech Posted July 14, 2016 Report Share Posted July 14, 2016 4 hours ago, KHE said: Don't jump the sensors - that is asking for additional troubles. @KHE I've jumped a lot of the connectors without problems, what kind of problems are you referring to? THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!! Link to comment Share on other sites More sharing options...
rockfangd Posted July 15, 2016 Report Share Posted July 15, 2016 Jumping connectors for testing is ok, but not for normal use. I dont recommend it but if you have a questionable switch it wont hurt. overfull refrigerant will also cause the compressor to cycle off. Too much pressure. a blocked condenser can be a issue also because if the condenser does not have sufficient air flow it will cause the high side pressure to be too high and cut off the system to prevent damage. The low pressure switch is common among many GM, Dodge, and other makes. For whatever reason. GM FAN FOREVER Nice, clean, luxury= fine automobile Link to comment Share on other sites More sharing options...
KHE Posted July 15, 2016 Report Share Posted July 15, 2016 13 hours ago, OldCadTech said: @KHE I've jumped a lot of the connectors without problems, what kind of problems are you referring to? Jumping the connector to the pressure switch would be OK if testing per my post above. Jumping the high/low temp sensors will just set a shorted code for that sensor and I tend not to want to start shorting out connectors that are connected to the ACM. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
KHE Posted July 15, 2016 Report Share Posted July 15, 2016 On 7/13/2016 at 7:56 PM, mike5plus5 said: About a month ago my A/C quit blowing cold. After 3 days it suddenly started working and has worked flawlessly since then until last Sunday when it suddenly quit blowing cold again. The compressor clutch engages for about 5 seconds, then disengages and won't engage again for approx. 1 minute, then repeats this cycle never staying engaged long enough to cool. It acts like maybe a stopped up orifice tube but I don't have a gauge to read the high side pressure so I don't know. Or that temperature control door (B0429) may have got stuck, again? It's been 4 days without A/C so far this time. All codes except RIM - DTC C0658 are current. IPC - DTC U1000 Class 2 Communication Malfunction IPM - DTC B0429 Temperature Control #3 Rear Circuit Range/Performance IRC - DTC U1064 Loss of Communications with DIM PCM - DTC P0422 Catalyst System Low Efficiency Bank 1 PCM - DTC P0741 TCC System Stuck Off PCM - DTC P1571 Traction Control Torque Request Circuit PCM - DTC P1860 TCC PWM Solenoid Circuit Electrical PCM - DTC U1040 Loss of Class 2 Communications with ABS RIM - DTC C0658 Level Control Compressor Circuit High (history) SDM - DTC U1000 Class 2 Communication Malfunction After start / run in park after cleared codes: IPC - DTC U1000 Class 2 Communication Malfunction / current IPM - DTC B0429 Temperature Control #3 Rear Circuit Range/Performance PCM - DTC P1571 Traction Control Torque Request Circuit PCM - DTC U1040 Loss of Class 2 Communications with ABS SDM - DTC U1000 Class 2 Communication Malfunction NOTE: (IPC - U1000, SDM - U1000 and IPM B0429 have been constant codes since I bought this car 3-19-2016 but A/C has always worked regardless) A clogged orifice tube won't result in intermittent A/C operation - it will just stop working and there may be a bunch of frost at the site of the restriction. Sometimes, the clutch gap gets too large due to wear from the clutch engaging/disengaging. Jack up the car, remove the right front tire and splash shield so you can see the A/C compressor pulley. If you have feeler gages, the clutch gap should be .020-.030". If you do not have feeler gages, start the engine, turn on the A/C at the climate control panel, then whack the pulley with a rubber mallet. If the clutch engages, you need to have the gap adjusted. There is a special tool to adjust the clutch air gap - don't beat on it with a hammer or anything like that. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
OldCadTech Posted July 15, 2016 Report Share Posted July 15, 2016 I guess I didn't make it very clear that I wasn't recommending a permanent jumper, just a momentary jumper to see if the compressor engages. Never a permanent jumper or by-pass. Sorry for the confusion. THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!! Link to comment Share on other sites More sharing options...
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