88-94 5.7 Suburban A/C Diagnosis and Tuning

[cjcb1100]

thats @ 87 deg F and 5 12 oz cans of 134a

 

[cjcb1100]

sanden says on this pump max 6000 rpm and 7000 downshift max my engine sees is 5k and the clutch dia is 119mm so i have no idea what the ratio is with stock crank pulley im no math wiz

i am thinking of getting the prom buring stuff and just increasing my idle speed in gear with ac and seeing if that helps im familiar with tuner pro and how to flash proms

 

[L31MaxExpress]

so a sanden will work fine at 840 rpm? internet says different

Not sure where you are getting that information. Mine has the 112mm or 4.409" pulley. I have a 6" crank pulley I ran. I did swap the crank pulley recently to the stock one (8" on a Vortec)to speed everything back up in our 108°F weather here. I noticed a little better cooling, but nothing earth shattering.

6/4.409 = 1.36 x 700 = 952 rpm. Mine was pulling dual evaporators well at 952 rpm in 108F.

 

[cjcb1100]

my crank pulley is 7&3/4

my pump info

New Sanden Type Flex Compressor 4864 with 8PV Clutch

Cylinder Head: GV
Volts: 12
Grooves: 8
Port Orientation: Horizontal
Mount Type: Ear
Compressor Type: SD7H15FLX
Gauge: 34
Refrigerant: R134A
Pulley Ridge Diam.: 119 is 4.685
Ports: Pad

 

[L31MaxExpress]

6" crank pulley

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8" crank pulley

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[L31MaxExpress]

7.75/4.685 = 1.65 x 5,000 = 8,271 rpm. I hope the the compressor has some form of WOT protection.

 

[L31MaxExpress]

I still do not understand why your setup needs anything close to 60 oz in it. Too much refrigerant will kill the system performance, especially at idle where the compressor can not pull down the suction pressure. Personally I would not want the pressure anywhere close to as high as the chart provided in the manual. To me those are worst case and a properly functioning system, with good airflow across the condenser should be much lower. The lower the pressures you can run, keeping the evaporator mostly flooded with liquid refrigerant, the colder the temps will be. I charge until the suction line off the accumulator starts to get cold and that is it.

 

[cjcb1100]

Basic Auto Air Conditioning Compressor Facts - Vintage Air

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alot of sights say they are far more efficient at above 1000 rpm

 

[cjcb1100]

well i dont know what to do then i'll just live with 60 degree air does the 90 have wot protection ? newer cars do my equinox does

 

[cjcb1100]

7.75/4.685 = 1.65 x 5,000 = 8,271 rpm. I hope the the compressor has some form of WOT protection.

well that means my truck is idling at 510 rpm i have never been able to get my idle up its always real low new iac and calibrate it and it always idles down way low i need to hook up a tach and see what its doing