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So I ended up buying that 01 Deville I talked about in another thread.Thanks to all who replied there.I like the car alot it runs and rides very well.Only problem is a less than ideal A/C.I have the vacuum pump and gauges to do the full service,I have done it on my old Seville,but that ended up in disaster when the compressor seized up.Dont know if it was somethinh I did or just coincident.It was a year after I did the service,so I aint sure.So here goes,I plan to do a simple recharge first,before I try to seize another compressor.Ha! Should I use freon with oil or use plain refrigerant with no additives? My old system was a conversion from R-12 to the newer 134 so I wasnt able to monitor the high side pressure as I didnt have the fitting for the high side port,it wasnt changed when someone did the conversion.I see on this 01 the two fittings are right next to each other and very easy to access.I dont have a manual for this car yet,is that little filter like thing located between these two ports?How do I know if I need to change it?Thanks in advance for any tips.

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The orifice tube is between the two ports. That is where the expansion takes place. These cars have great A/C so if yours is not cooling well it could be a little low on refrigerant. I would hook up the gages and see what the high and low side readings are. Also check the vent temperature when the system is set to 60 degrees. Knowing the ambient air temperature is helpful.

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

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My gauge and pump are home,but I had one of those applicators with the single dial here,so I havent checked the high side pressure yet.I got a large can of "Arctic Freeze" and it took most of it to bring me up to 48psi which seems to be right for the 90+ temp here today.It works better now,I'll see how much pressure I got tomorrow,hopefully its not a leak.Before I added the can it was 30psi.I'm heading home tomorrow,I'll check it with the real gauges,high side as well.How often should the orrifice tube be changed?I drew a blank on the name of that in my original post,thanks.

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The orifice tube is usually only changed when there is a problem with the compressor that generated debris in the system. It is not a regular maintenance item.

48 psi on the low side seems high to me. I'd need to look in the shop manual to see what the low side should be at 90+ degrees and high humidity.

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

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Thanks,dont have a manual yet.The dial gauge I used has the psi/ambient temp guide and shows 55psi is max at 90 deg.I have some charts and info with my gauges at home,I'll check when I get there.Good to know about the orifice tube,I thought it was some type of filter and needed to be serviced from time to time.

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Should I use freon with oil or use plain refrigerant with no additives?

Definitely don't use freon with oil in it. You don't want to end up having too much oil in the system. Having the correct amount of oil in the system is important so first check how much oil your A/C needs. What I usually do when things are unknown is pull off the compressor and dump as much of the previous oil out as possible. I also blow out the lines and try to get as much oil out of the accumulator as possible by also removing it.. Before replacing the compressor, add about 4 oz of oil to it. Also add another 4 oz of oil to the accumulator. Be sure to also replace all the O-rings. Doing that while it is discharged is the best time to do it. I hope you're not using one of those vacuum pumps that hooks up to a compressor.

Edited by Ed Hall
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Thanks,dont have a manual yet.The dial gauge I used has the psi/ambient temp guide and shows 55psi is max at 90 deg.I have some charts and info with my gauges at home,I'll check when I get there.Good to know about the orifice tube,I thought it was some type of filter and needed to be serviced from time to time.

I wouldn't trust any of the guides that come with the low-side only gages. It is impossible to have a one guide fits all vehicles spec.

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

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Thanks,dont have a manual yet.The dial gauge I used has the psi/ambient temp guide and shows 55psi is max at 90 deg.I have some charts and info with my gauges at home,I'll check when I get there.Good to know about the orifice tube,I thought it was some type of filter and needed to be serviced from time to time.

I wouldn't trust any of the guides that come with the low-side only gages. It is impossible to have a one guide fits all vehicles spec.

Thats why I ddnt take it to the max pressure on that gauge.I just drove home,have my real gauges here,but since I dont have a manual for this car yet,I'm not 100% on what the correct psi should be,so going by things I see on the net,I'll just use a safe mid level for now.On the drive home,the AC was blowing very cold,pressure still reads the same,so I am assuming it isnt leaking,all good to me.

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With the real gauges and an ambient temp of 99 I see 49psi on the low side and 227psi on the high side.The 49psi does seem a little high,but since the psi rises a lot when the unit is turned off,I think it is safe to assume the unit can take it.Am I wrong here?It is blowing ice cold.Riding back upstate this afternoon I was able to turn the fan down a lot and raise the temp control to 65 and it was still comfortable with a window open slightly because I smoke and drive with the window open most of the time.The outside temp read 101 on the highway.Unless you think it is too high I'm just gonna leave good enough alone.Whats your thoughts KHE?

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With the system off, both side equalize and the low side will rise, while the high side decreases, but those readings are useless. I thought the low side should be 30-35 and the high side should be 2 - 2.5 times the outside temperature or 180 - 225 at 90 degrees (system running).

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I realize that the readings while the unit is off really mean nothing,what my point was that if the unit can withstand 100psi while sitting idle,the 48psi while it is running shouldnt hurt anything,but thats just an assumption.Yes,from what I've read,the high side should be 2.2 to 2.5 times the outside temp,so the 227psi I saw at 99 deg isnt far off.Before I added refrigerant my low side pressure was 30psi and it blew warm.I dont have a service manual for this car yet,so I'm going by generic instructions I've been reading online.

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Are you taking the pressure readings right before the compressor shuts off? That will be the highest high side reading and the lowest low side reading.

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

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