: Northstar A/C



Cadillac Roller
05-19-11, 07:43 AM
Got my Northstar up and running okay as has been sitting a while. Engine and all runs fine, transmission is fine and only 85,000 on the clock. Only trouble is the A/C system comes up with "Low Refrigerant" and also "Compressor off". Have filled with 134a and oil but still the indication shows the compressor off. How do I get the compressor to run? It is a very nice well kept leather and wood vehicle. Very nice to drive but even nicer if it was cooler inside.

Note. The A/C gas was removed as the vehicle needed a top up of A/C gas so emptied system to add oil and gas. Now have the above problem where as before the A/C was working but not cold just cool but the compressor was running. All the fans in the car run and all fuses and relays work okay. Wiring checks out okay and all fault codes can be removed with my Nemysis diagnostic tool.

Please let me know thoughts as to cause.

Thank you in advance for your sugestions.

89falcon
05-19-11, 09:01 AM
I think you have to clear the code on that one to make it work again.....

Falcon

stoveguyy
05-19-11, 11:34 AM
code says low a/c pressure? you can evac the system and get quite a bit of freon back into system even with compressor off. easily enough to satisfy pressure sensor so compressor will run. so compressor is not running now. how much freon do you believe is in system?

mhamilton
05-19-11, 12:10 PM
You have to clear that B code before the PCM will enable the compressor again. It isn't a pressure sensor issue. The "low refrig" code is set by the temp differential it gets from the thermistors.

Ranger
05-19-11, 12:29 PM
Why did you add oil?

Cadillac Roller
05-20-11, 12:09 AM
89falcon, Thank you for your coments but do not understand how to remove the code as the Nemisys has already removed all trouble codes. It removes the low refrigerant level warning as well but still the compressor won't run.

Stoveguyy, Thank you for your reply, I have 45 psi in low side and 115 psi. I got this by removing the A/C relay and crossing terminals of the contacts to get compressor running. Good cold air comes out but when relay inserted the compressor won't run and the facia for the AC has "AC off" no matter what I do with the Nemisys.

mhamilton, Thank you for your help, I have no idea on the B code or where it is located and how to clear it. Can you help in location or removal of this code as I have not been able to locate any B code.

Ranger, Thank you for your question. Most times when the AC gas leaks the oil that is carried with the gas also leaks out. To just refill with gas can reduce the compressor life as the oil escapes and the top up of gas increases the load on the compressor with low oil. Hence to fill or do a major top up of A/C gas I always remove the old gas and oil and replace with recomended quantities to help extend the compressor life. I hope this helps your question.

With the contacts bridged 3 + 5 on the AC relay the A/C system works very well. I have checked the relay and it is 100% okay.

At present am removing all gas again and will add oil and re-gas the unit as much as possible without starting the engine or turning the ignition key on. this should give about 45 psi through the system and hopefuly re-set the thermisters registering again.

Any more help would be much appreciated.

Thanks to all those that help here.

vincentm
05-20-11, 08:32 AM
By gas you mean the R134a refigerant?

-------------------------------------------------------
Sent from my Northstar powered phone

89falcon
05-20-11, 10:21 AM
89falcon, Thank you for your coments but do not understand how to remove the code as the Nemisys has already removed all trouble codes. It removes the low refrigerant level warning as well but still the compressor won't run.

Stoveguyy, Thank you for your reply, I have 45 psi in low side and 115 psi. I got this by removing the A/C relay and crossing terminals of the contacts to get compressor running. Good cold air comes out but when relay inserted the compressor won't run and the facia for the AC has "AC off" no matter what I do with the Nemisys.

mhamilton, Thank you for your help, I have no idea on the B code or where it is located and how to clear it. Can you help in location or removal of this code as I have not been able to locate any B code.

Ranger, Thank you for your question. Most times when the AC gas leaks the oil that is carried with the gas also leaks out. To just refill with gas can reduce the compressor life as the oil escapes and the top up of gas increases the load on the compressor with low oil. Hence to fill or do a major top up of A/C gas I always remove the old gas and oil and replace with recomended quantities to help extend the compressor life. I hope this helps your question.

With the contacts bridged 3 + 5 on the AC relay the A/C system works very well. I have checked the relay and it is 100% okay.

At present am removing all gas again and will add oil and re-gas the unit as much as possible without starting the engine or turning the ignition key on. this should give about 45 psi through the system and hopefuly re-set the thermisters registering again.

Any more help would be much appreciated.

Thanks to all those that help here.

I don't really know the inner workings of a 2005...but on my 1997, I had the same messages......what worked for me: Attach 134 hose to system.......turn on flow (with Car on and temp set to 60 degrees).....would then clear the code....and compressor would come on....if one can wasn't enough.....message would come back up, and compressor would turn off....I'd attach another can to the hose...start flow and reset code (with temp at 60 and car running)....lather rinse repeat.......

But that was on a 1997....wouldn't be surprised at all if the 05 has additional "protections".....

I guess something that hasn't been asked.....have you checked the connections at the pressure sensors?

Falcon

stoveguyy
05-20-11, 10:26 AM
your post is in the "northstar motor" section. there is a eldo/seville section and a deville section. but not really a heating/ventilating section. usually the questions in this section are motor related. accessing the B codes is meant to say body codes. you will get into a/c codes if you keep digging.

RippyPartsDept
05-20-11, 10:53 AM
1985-2005 FWD Deville Forum: http://www.cadillacforums.com/forums/cadillac-deville-1985-2005-including-1985/
DTC "HOW TO" Sticky: http://www.cadillacforums.com/forums/cadillac-deville-1985-2005-including-1985/138257-how-pull-codes-dtcs.html

Ranger
05-20-11, 11:16 AM
Ranger, Thank you for your question. Most times when the AC gas leaks the oil that is carried with the gas also leaks out. To just refill with gas can reduce the compressor life as the oil escapes and the top up of gas increases the load on the compressor with low oil. Hence to fill or do a major top up of A/C gas I always remove the old gas and oil and replace with recomended quantities to help extend the compressor life. I hope this helps your question.
I understand that, but unless you have a sudden and catastrophic pressure loss, you don't need to add oil unless you are removing it, but I can't imagine how you could do that unless you remove each component and drain it. Too much oil is as bad as not enough.




89falcon, Thank you for your coments but do not understand how to remove the code as the Nemisys has already removed all trouble codes. It removes the low refrigerant level warning as well but still the compressor won't run.
See the DTC sticky at the top of the forum page. The instructions are there.




Stoveguyy, Thank you for your reply, I have 45 psi in low side and 115 psi.
Low side sounds a little high and the high side is WAY low.

mhamilton
05-20-11, 12:11 PM
Oh, wait... a 2005 Deville? What year did GM get rid of the "hvac diagnoistic access" system? It may not have the ability to clear codes the way the older models could. Most handheld scanners will not read anything but PCM codes (B codes are BCM). If you can't read codes onboard, disconnect the battery for an hour and it should reset them. I'm not 100% sure though,


I have 45 psi in low side and 115 psi.... Low side sounds a little high and the high side is WAY low.

That's undercharged. Depending on ambient temp, high side will be around 200 psi, low side in the 20-30 psi range.

stoveguyy
05-20-11, 12:26 PM
pressures are close to static. sounds like a failing compressor or poorly performing.

Ranger
05-20-11, 05:06 PM
Oh, wait... a 2005 Deville? What year did GM get rid of the "hvac diagnoistic access" system?
I want to say '06. I think the 2000 - 2005 are basically the same.

RippyPartsDept
05-20-11, 05:37 PM
2006 Was the first year that devilles did not have onboard diagnostics
2005 was the first year that the 'seville' (rebranded the STS) did not have it
in 2003 some CTS could pull up codes through the DIC, but not all (i'm not sure what's up with that)

Cadillac Roller
05-21-11, 10:11 AM
A big thank you to all. With all the help I was able to get the A/C up and running with oil and gas and nice and cool inside.

Disconected the battery for an hour with the A/C system Vaced out, new gas in, connect battery and started engine with A/C on and Compressor ran as smooth as.

The car has 85,000Kms on it, it is not a miles car, and is like new except the right rear tail light damage where some bod has tried to slam the boot shut many times with a flat battery in the car. As you no doubt know the boot can not be shut unless there is power on and it shuts and locks automatically.

Have a truly great weekend and again thank you all for your wisdom. Happy motoring.

myboneyard
06-14-11, 10:36 AM
Sorry for jacking the tread, but i have a question....I had my compressor switched out and my ac blows but its not cold...its cool only when the car is idled....i thought it was low on 134 so i tried to add some , but the pressure gauge on the can say (warning)...it has too much pressure..any thoughts..i dropped the car off to a local mechanic(i know, big mistake)...so im not sure if the system was emptied , recharged or whatever else...any tips/help would be much appreciated...

89falcon
06-14-11, 10:54 AM
did they change out your orifice valve? it's a tiny part that cost less than $5....it basically drops the pressure on the freon going to the evaporator.....if it gets partially clogged from the crapped left in the lines from the compressor change, your AC ceases to work.

Does you AC compressor cycle on and off?

Caddyman1999
06-14-11, 11:11 AM
Hello my friend same problem on my caddy you cannt delet this code with an obd2 scanner. What I did to get the compesser to kick over is bought a nice set of gages got the A/C charged to 125 psi on cold and hot side with compesser off. Nothing would not kick over I disconected the battery four three hours the low frefg light went off no ac still I set the A/C to 60, high with car on and I got donw looked at the compresser the clutch was not spinning so I spined it by hand well the seconde I touched it, it turned over and it has not gotten stuck since be carfull a lot of moving parts do not attempt to turn the.clutch by hand from the top I did mine from under neath much easyer. I beleave when the computer shut the compresser off the cluthch would not engage on its own. Good luck keep me informed.

Caddyman1999
06-14-11, 11:14 AM
Just saw you have solved your problem if it happens again try turning the clutch.by hand ofter.battery is disconected and reconnected.

Caddyman1999
06-14-11, 11:19 AM
I have a question about my caddy and I am new to this sight can any one help me. I need to know how to post a new form for my problem. I am not seeing anything that says ask question. Thank you for your time.

vincentm
06-14-11, 03:20 PM
I have a question about my caddy and I am new to this sight can any one help me. I need to know how to post a new form for my problem. I am not seeing anything that says ask question. Thank you for your time.

Just use the button that says "Post New thread"

Cadillac Roller
06-16-11, 05:26 AM
Sorry for jacking the tread, but i have a question....I had my compressor switched out and my ac blows but its not cold...its cool only when the car is idled....i thought it was low on 134 so i tried to add some , but the pressure gauge on the can say (warning)...it has too much pressure..any thoughts..i dropped the car off to a local mechanic(i know, big mistake)...so im not sure if the system was emptied , recharged or whatever else...any tips/help would be much appreciated...


My RR was cool at idle and above went warm. Reduced the amount of coolant and the A/C started working fine. If too high the A/C will not work, if too low the same results. Presume this to be the same with yours. As standard practice replacement of compressor means replace orrafice and drier. Fill with correct amount of newly opened oil and re-gas.

myboneyard
06-20-11, 11:09 AM
did they change out your orifice valve? it's a tiny part that cost less than $5....it basically drops the pressure on the freon going to the evaporator.....if it gets partially clogged from the crapped left in the lines from the compressor change, your AC ceases to work.

Does you AC compressor cycle on and off?

Yes...I changed orifice tube, the dryer and i still have hot air after adding freon......is the compressor suppose to cycle on and off constantly?
I only hear it cycle on when first turned on ...but the compressor clutch is spinning, but it doesnt cycle on and off....please a little help would be appreciated...could it be the compressor is bad?...it was not purchased new..

Ranger
06-20-11, 11:54 AM
Yes, the compressor will cycle on and off. Cycle lengths will vary with ambient temperature. The hotter it is, the longer it will run and may run continuous in real hot temps.