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A/C problem - 98 Deville


boots

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Can't seem to find anybody with a problem just like mine. Ranger thinks the great minds here can help. Last week the A/C started to blow warm air, but would cool a little at Hwy speeds. No codes. 98 Deville has 66K and never been recharged. Put the gauges on and at idle speed, low side showed 90 psi. I am not an A/C man, but I think that should be much lower (25-30psi) High side at idle was 150psi. At half throttle low side dropped to only 45psi and high side went to 250psi. Dryer would start to get cold when throttled up and while driving.

Compressor stayed on entire time, not getting cold enough to ever shut off I assume. Both fans are running and radiator appears to be fine.

Any help, suggestions, thoughts or comments would be appreciated.

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Can't seem to find anybody with a problem just like mine. Ranger thinks the great minds here can help. Last week the A/C started to blow warm air, but would cool a little at Hwy speeds. No codes. 98 Deville has 66K and never been recharged. Put the gauges on and at idle speed, low side showed 90 psi. I am not an A/C man, but I think that should be much lower (25-30psi) High side at idle was 150psi. At half throttle low side dropped to only 45psi and high side went to 250psi. Dryer would start to get cold when throttled up and while driving.

Compressor stayed on entire time, not getting cold enough to ever shut off I assume. Both fans are running and radiator appears to be fine.

Any help, suggestions, thoughts or comments would be appreciated.

Is there any frost on the lines? If so, where does it end?

Your orifice tube may be plugged - 90psi on the low side is not much more than static pressure.

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

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Kevin, you are teaching me! You know, I was thinking the same thing, that the orifice tube might be clogged especially after seeing mine clogged, but I don't have enough experience to give advice yet... Thanks

If his orifice tube is clogged, do you clean it or is it then necessary to find the source of the debris and then flush the system?

I promise, I am under my car doing the AC this Saturday! Its getting HOT here....

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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Kevin, you are teaching me! You know, I was thinking the same thing, that the orifice tube might be clogged especially after seeing mine clogged, but I don't have enough experience to give advice yet... Thanks

If his orifice tube is clogged, do you clean it or is it then necessary to find the source of the debris and then flush the system?

I promise, I am under my car doing the AC this Saturday! Its getting HOT here....

If the orifice tube is clogged, that's a sure bet that the compressor is on its way out... Just replace the orifice tube as they are less than $5. The system will need to be flushed to remove all traces of debris.

Yeah - it's been hot and humid here too for the last week.

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

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Kevin, how much nylog do I use on my o-rings? a drop or two? While they are in place or before I slide them on? Thanks

I am going to use the nylog but the place I am having it recharged said not to use it... they said to use wd40 on the threads and that the oring will seal on its own.

I am going to use the nylog as per your instructions, as I don't want leaks..

When I put the oil in the compressor how much do I need to work it in by turning the compressor? how many rotations and in both directions? Thanks

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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Kevin, how much nylog do I use on my o-rings? a drop or two? While they are in place or before I slide them on? Thanks

I am going to use the nylog but the place I am having it recharged said not to use it... they said to use wd40 on the threads and that the oring will seal on its own.

I am going to use the nylog as per your instructions, as I don't want leaks..

When I put the oil in the compressor how much do I need to work it in by turning the compressor? how many rotations and in both directions? Thanks

Always coat the o-rings with either 525 viscosity mineral oil (R-12 oil, not PAG oil)or Nylog. I coat the o-rings with the Nylog. You can also use the nylog on the threads as an anti-sieze. You can also use a small amount of anti-sieze compound on the threads.

Add the oil to the suction port of the compressor (the side where the pipe from the accumulator connects) and rotate the clutch in the same direction that it will rotate when it is in-use in the vehicle. Go slowly or it will spray out the discharge port....don't ask me how I know that :lol: .....When the compressor won't take any more oil, add the balance of the full charge to the accumulator.

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

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Thanks Kevin, I am very excited about doing this job this weekend...

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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Can't seem to find anybody with a problem just like mine.  Ranger thinks the great minds here can help.  Last week the A/C started to blow warm air, but would cool a little at Hwy speeds.  No codes.  98 Deville has 66K and never been recharged. Put the gauges on and at idle speed, low side showed 90 psi. I am not an A/C man, but I think that should be much lower (25-30psi) High side at idle was 150psi. At half throttle low side dropped to only 45psi and high side went to 250psi. Dryer would start to get cold when throttled up and while driving.

Compressor stayed on entire time, not getting cold enough to ever shut off I assume.  Both fans are running and radiator appears to be fine.

Any help, suggestions, thoughts or comments would be appreciated.

Is there any frost on the lines? If so, where does it end?

Your orifice tube may be plugged - 90psi on the low side is not much more than static pressure.

Kevin,

90 psi on the low side seemed rather high to me, no? Likewise with 250 on the high side. The thing I found confusing is that they did not stay there, but then I am still learning (from you) about A/C, that's why I told Boots & GM-MAN to check in here with you.

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Can't seem to find anybody with a problem just like mine.  Ranger thinks the great minds here can help.  Last week the A/C started to blow warm air, but would cool a little at Hwy speeds.  No codes.  98 Deville has 66K and never been recharged. Put the gauges on and at idle speed, low side showed 90 psi. I am not an A/C man, but I think that should be much lower (25-30psi) High side at idle was 150psi. At half throttle low side dropped to only 45psi and high side went to 250psi. Dryer would start to get cold when throttled up and while driving.

Compressor stayed on entire time, not getting cold enough to ever shut off I assume.  Both fans are running and radiator appears to be fine.

Any help, suggestions, thoughts or comments would be appreciated.

Is there any frost on the lines? If so, where does it end?

Your orifice tube may be plugged - 90psi on the low side is not much more than static pressure.

Kevin,

90 psi on the low side seemed rather high to me, no? Likewise with 250 on the high side. The thing I found confusing is that they did not stay there, but then I am still learning (from you) about A/C, that's why I told Boots & GM-MAN to check in here with you.

70-90 PSI on the low side is close to static pressure. (compressor not running). If the system was overcharged, there would be a high reading on the high side as well but 250 is in the ball park.

I have to install a new condenser in my old Park Avenue tonight....while the vacuum pump is evacuating the system, I'll post back additional detail.

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

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boots,

Have you added any R-134a to the system??? If so, DO NOT add any more. Your readings seem to indicate that the system is overcharged but that doesn't correlate with your initial symptoms. You stated that the system started to blow warm air - was it cooling OK properly prior to starting to blow warm?

Did you inspect the lines for frost while the compressor is running? If so, where does the frost start?

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

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