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Question about DIC message


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This is probably my simplest topic yet.

Ok. So for the 3rd time today I have had the message "VERY LOW REFRIGERANT A/C COMPRESSOR OFF" show up on my DIC. My question isn't about what it means because that's pretty obvious to me. I need to refill my refrigerant, check for leaks, and repair if needed. No big deal. The only confusing part to me is that the first time it happened I didn't have the climate control on at all, the second time I had it on with it set to 90 degrees so it was blowing heat only, and the 3rd time was the same as the first, completely off. It doesn't happen every time I drive the car, just 3 times out of 5 or 6 times driving it the last couple days. So, my 2 questions are:

1. Does the A/C compressor run even when the climate control is turned off? I've never had a car with full climate control before, so I don't know.

2. If I ignore taking care of it for a while (a couple weeks) is it going to hurt anything or cause any other problems?

Sorry if I sound like an idiot but as I said, I'm not used to the dual climate control thing, and I don't want to put off fixing it if it will affect anything else. If I can I would rather wait so I can get my other issues resolved first.

For those who don't know, it's a 1994 Eldorado 4.6 Northstar.

Thanks ahead of time.

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The AC compresser will run at odd times like when you have your defroster on to provide dehumidified air

The PCM will sense that the freon is LOW from the Low Pressure Sensor.

Sometimes the Low Pressure Sensor can be bad

When you have the AC system checked, they can determine if it needs freon, if NOT the low pressure sensor is at fault.

If you clear that code will it cool at all? You can leave the code for a while until you can get it charged. Don't have them use sealer and dont be tempted to use sealer, have them put dye in, in case you have a leak, you will see it

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

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I didn't have the defroster on either. Would you happen to know what the proper pressure is for the AC system? It would be easier for me to just check that myself to see if I do need to fill it, or if the sensor is at fault. If it is the sensor, is it hard to change?

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The system does a test everytime the car is started, it sensed the AC was low...bam AC low pressure code, it shuts off the compresser to protect it....

I am not an AC person, KHE should stop by. Its probably low pressure and not the sensor, replacing the sensor is easy, I dont think the system needs to be depressurized if I recall, its along the wheelwell on the passenger side.

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

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The low pressure sensor is #13

1996_AC_System.jpg

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

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The low pressure sensor is #13

1996_AC_System.jpg

That seems easy enough, and it's only a 14$ part. I'll check the pressure first and see what that looks like.

This image is slightly different than what my car looks like. My compressor sits upright rather than lying down and is closer to the coolant tank, next to the battery. I believe the lines also run alongside the coolant tank rather than up and over it. I can't remember off hand.

I would guess that since the compressor turns off, I shouldn't have to worry about anything bad happening if I don't refill it right away.

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That diagram is from a 96

Lets see what KHE says

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

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Carla, was the system in AUTO? The compressor will run all the time in AUTO when the ambient temperature is above about 35 degrees.

Low side pressure should be around 35 psi. High side should be roughly 2 1/2 times the ambient temperature.

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I believe 1993 was the last year that used R12 (liquid gold) and your 1994 uses 134a. My money is on the compressor seal. I would throw in a can of 134a and see how long it holds. It could be that you are just a little low on freon. My 84 corvette takes about a can every other year and this a lot cheaper than a compressor replacement. I have a similar problem with my 93 Eldo, low coolant message, I had my brother-in-law top off the R12, unfortunately it only lasted about a month.

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To Ranger: No. the system was turned off completely. It was warm out side (comparitively) and I had the sunroof open so I didn't bother turning anything on. Also, I never use AUTO. I always use ECON because I can hear a chirping noise from the car when it's on AUTO. It's a strange chirp. Happens at perfectly spaced intervals of about 10 seconds and is most audible on the passenger side. Perhaps it's the AC compressor since, well, that IS on the passenger side. Didn't think of that before. the ECON setting however does not do that.

BSchlossmann: You are right that mine takes 134a. I'm thankful for that because the R12 is VERY hard to find around here. It could have a leak. It is a 16 year old car after all. Though it is from Texas, so my bet is that the prior owner made sure the AC was in working order, or at least kept it full at all times. I don't want to be without AC here in New York. I could just imagine what a nightmare that would be in Texas!

I'll see if I can go grab my dad's pressure gauge in the next day or two and see how that looks. He also has this dye stuff that you can put in it to help find a leak. I guess it's a dark blue/purple, and if there is a leak you will be able to see it because of the dye, and it's harmless to the system. If there is a leak, I'm sure that will help me to find it. It worked for him to find the AC leak on his Chrysler.

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I believe 1993 was the last year that used R12 (liquid gold) and your 1994 uses 134a. My money is on the compressor seal. I would throw in a can of 134a and see how long it holds. It could be that you are just a little low on freon. My 84 corvette takes about a can every other year and this a lot cheaper than a compressor replacement. I have a similar problem with my 93 Eldo, low coolant message, I had my brother-in-law top off the R12, unfortunately it only lasted about a month.

The problem with the '93 Eldorado may be leaking case seals on the compressor. A somewhat common problem with the HR-6 compressor. The existing compressor can be repaired cheaper than a new one or a junk chain store remanufactured compressor but some special tools are needed. A new teflon double lip shaft seal would be a wise choice for replacement while the compressor is off/out of the car. That seal won't leak - EVER.

To Ranger: No. the system was turned off completely. It was warm out side (comparitively) and I had the sunroof open so I didn't bother turning anything on. Also, I never use AUTO. I always use ECON because I can hear a chirping noise from the car when it's on AUTO. It's a strange chirp. Happens at perfectly spaced intervals of about 10 seconds and is most audible on the passenger side. Perhaps it's the AC compressor since, well, that IS on the passenger side. Didn't think of that before. the ECON setting however does not do that.

BSchlossmann: You are right that mine takes 134a. I'm thankful for that because the R12 is VERY hard to find around here. It could have a leak. It is a 16 year old car after all. Though it is from Texas, so my bet is that the prior owner made sure the AC was in working order, or at least kept it full at all times. I don't want to be without AC here in New York. I could just imagine what a nightmare that would be in Texas!

I'll see if I can go grab my dad's pressure gauge in the next day or two and see how that looks. He also has this dye stuff that you can put in it to help find a leak. I guess it's a dark blue/purple, and if there is a leak you will be able to see it because of the dye, and it's harmless to the system. If there is a leak, I'm sure that will help me to find it. It worked for him to find the AC leak on his Chrysler.

Make sure to monitor both the high and low side pressures. You could just add one can of R-134a and see how the system performs. 99.9% of the time, when the DIC says the system is low on refrigerant, it IS low on refrigerant. Check your compressor body for oily/greasy residue - if the clutch face is all full of oil, the shaft seal is leaking. If the body is all greasy, the case seals are leaking. This assumes engine oil is not leaking and blowing on the compressor.

You have time to get it fixed - the system disables the compressor when a low refrigerant condition occurs to prevent the compressor from being damaged. You will need to hook up the can of R-134a to the system, burp the air from the lines and then clear the low refrigerant code or the system will not draw in the refrigerant from the can.

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

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I believe I changed that sensor on my buddies 99 deville. We bought the new one and I noticed it had PLASTIC threads! First I tried tightening the old sensor and noticed it was stripped. It had probably been replaced and tightened too tight and thats why it was leaking. So just be carefull installing the new sensor if it has those plastic threads.

Also the guys are right, your a/c compressor will run even with the heat on. Otherwise your car would steam up inside during the winter. Not everytime but if conditions are right it will. Thats why there is a a/c button on most climate controls i believe because if you are one that believes you get way worse gas mileage with the compressor on you can shut it off manually while your heat is on. Sitting in fast food drivethrus with my heat on and my window open I can hear the compressor click on and off. Plus you get that message because all systems are sending and receiving info at all times, or it collected the information the last time you drove and had the climate controls on.

* 1966 Deville Convertible

* 2007 Escalade ESV Black on Black

* 1996 Fleetwood Brougham Black on Black V4P -Gone
* 1983 Coupe Deville Street/Show Lowrider -Gone

* 1970 Calais 4dr Hardtop GONE
* 2000 Deville DTS - Silver with Black Leather and SE grille GONE
* 1999 Seville STS - Pearl Red GONE

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KHE, I will check the compressor. I know I don't have an oil leak anywhere near it.

Also, just to clarify things, the message usually shows up about 5-10 minutes into driving. Never right away when I start it. My climate control does not have an AC button. Instead I have the programmable thermostat that ranges from 65-90 degrees F. It has AUTO, ECON, DEFOG, and OFF as settings along with the warmer/cooler buttons and defrosters. 2 of the 3 times I have seen the message so far, my climate control was completely off. No heat. No defog. No defroster. That was what made me wonder if it could be a "glitch" so to speak.

I will take KHE's advice and fill it up, then go from there if there are any other problems. I'll grab a can this weekend. I just have one other question. How do I burp the air from the system prior to filling it? I've never had to refill an AC system, and wasn't aware this had to be done. Thanks for the forewarning.

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How do I burp the air from the system prior to filling it? I've never had to refill an AC system, and wasn't aware this had to be done. Thanks for the forewarning.

Be sure to wear safety glasses and gloves when working with refrigerant.

Using a manifold gage set, make sure the hose valves are closed. Connect the can of refrigerant to the yellow hose and then open the blue, low side valve on the manifold (near the gages)slightly and then crack the valve on the end of the blue hose until a small amount of refrigerant escapes. Close the valve at the end of the hose and then close the blue valve near the gage manifold.

Be sure the red high side valve near the manifold is closed to prevent high pressure from bursting the can.

Once the manifold is connected to the car (blue is low side, red is high side and the connectors are unique so you can't get the hoses mixed up), open the valves AT THE HOSE(VEHICLE) ENDS. DO NOT UNDER ANY CIRCUMSTANCES OPEN THE RED VALVE NEAR THE GAGES.

Clear the low refrigerant code, open the blue valve near the hose connection and open the blue valve near the gages slightly. Hold the can of refrigerant upside down to charge as a liquid. Have a helper start the engine and Set the climate control to AUTO and the refrigerant will be pulled in. Note the pressure readings right before the compressor switches off.

Honestly, I would wait on this task until we get a 70 degee day - the pressures in the shop manual are set up for 70 or 80 degrees and it will be easier to approximate a full charge. No harm will be done to the system by waiting.

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

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I will take your advice and wait for a warmer day. It's supposed to be in the 60's here this weekend last I checked, so maybe we will see a 70 degree day in the not-so-distant future. Thanks a lot.

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I never use AUTO. I always use ECON because I can hear a chirping noise from the car when it's on AUTO. It's a strange chirp. Happens at perfectly spaced intervals of about 10 seconds and is most audible on the passenger side. Perhaps it's the AC compressor since, well, that IS on the passenger side. Didn't think of that before. the ECON setting however does not do that.

Carla, that chirp is the belt slipping as the compressor engages. It cycles on and off. Check your tensioner. If it's OK, then you may need a new belt.

ECON is the same as A/C in most other cars. It's just an A/C bypass switch (runs the system in AUTO without A/C).

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I never use AUTO. I always use ECON because I can hear a chirping noise from the car when it's on AUTO. It's a strange chirp. Happens at perfectly spaced intervals of about 10 seconds and is most audible on the passenger side. Perhaps it's the AC compressor since, well, that IS on the passenger side. Didn't think of that before. the ECON setting however does not do that.

Carla, that chirp is the belt slipping as the compressor engages. It cycles on and off. Check your tensioner. If it's OK, then you may need a new belt.

ECON is the same as A/C in most other cars. It's just an A/C bypass switch (runs the system in AUTO without A/C).

The belt was replaced less than a year ago, so I'm pretty sure there's no problem there. I'll check the tensioner though. Could it also be the pulley on the compressor itself that is chirping?

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Its probably the tensioner not applying enough tension but consider that your compressor's hub bearing is bad, take the belt off and feel the hub bearing for looseness or roughness, see if you can cock it from side to side at all

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

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Nothing else that runs off that belt has any problems or makes any noises. I'll still check out the tensioner, along with the hub bearing on the compressor. I'm sure it's not the belt. It seems unlikely for a less-than-a-year-old belt to have anything wrong with it, and it looks fine. Not a mark on it.

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You know it just dawned on me that the chirp you are hearing is the AC clutch, chirping when it engages, its not the serp belt.

There is a way to adjust the AC clutch and to clean it in case it has grease on its surfaces....

KHE will chime in on this

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

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The clutch air gap may be a tad too wide - It should be .020-.030". A special tool is needed to adjust the gap. If it is oily/greasy, brake cleaner spray should clean it up.

Edited by KHE

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

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Thanks. I'll look into that as well. I'm bringing my car to my brother's garage to do an oil change either today or tomorrow so I will check it out then. It's raining now and is supposed to for the next 3 days, so I really don't want to do anything outside.

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