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1996 Tahoe AC problems

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Old Jul 10, 2013 | 10:45 PM
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Default 1996 Tahoe AC problems

:cool:I recently purchased this 1996 Tahoe. Its ac cycles on for 3 seconds and off for 10 seconds. At first it blew only hot air so I put a can of Freon in and it started cooling. The following day it would not cool again. I put a set of gages on and the low side pressure varied from 10-70 psi as it cycled. The high side pressure reads about 35 psi and when I press down on the red high pressure coupler the pressure reads a variance of 100-150 psi as it cycles. Can anyone help with advice or guidance on how I might proceed with repairing this AC problem.
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Old Jul 10, 2013 | 11:39 PM
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80 degrees and 60% humidity the Pressure should be around: High: 140~190 psi Low: 30~45 psi.

Let me know the temp and humidity you are working with.
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Old Jul 11, 2013 | 10:58 AM
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The temp is 100 and humidity is 35%.
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Old Jul 11, 2013 | 12:24 PM
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Ok, the official performance test:
1.) Park inside garage or shaded area.
2.) Take note of Temp and Humidity
3.) Hook up High & Low pressure gauge to A/C under the hood
4.) Close all doors and windows.
5.) For rear A/C option turn rear A/C on
6.) Turn on main A/C set temp to full Cold and blower to High
7.) Open all of the A/C vents
8.) Place Thermometer in right center vent
9.) Stabilize engine speed at 2000 RPM in Park
10.) Run the A/C for At-least 3 minutes
11.) Record the A/C temp and Low and High Pressures.

Data for 100 Degrees and 30~40% humidity engine @ 2,000 RPM

Low Pressure: 31~37 PSI MAX
High Pressure: 328~361 PSI MAX
A/C Outlet Temp: 53~59 degrees MAX
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Old Jul 11, 2013 | 4:11 PM
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Ok I did the test.

Temp 100
Humidity 41
AC temp in degrees at vent after 3 min @ 2000rpm = 100
Low pressure reading cycling variation 15-47 psi
High pressure reading 50 psi but if I hold downward pressure on coupling the pressure varies by cycling at 60-110 psi
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Old Jul 11, 2013 | 10:06 PM
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Originally Posted by Joe In NY
Ok, the official performance test:
1.) Park inside garage or shaded area.
2.) Take note of Temp and Humidity
3.) Hook up High & Low pressure gauge to A/C under the hood
4.) Close all doors and windows.
5.) For rear A/C option turn rear A/C on
6.) Turn on main A/C set temp to full Cold and blower to High
7.) Open all of the A/C vents
8.) Place Thermometer in right center vent
9.) Stabilize engine speed at 2000 RPM in Park
10.) Run the A/C for At-least 3 minutes
11.) Record the A/C temp and Low and High Pressures.

Data for 100 Degrees and 30~40% humidity engine @ 2,000 RPM

Low Pressure: 31~37 PSI MAX
High Pressure: 328~361 PSI MAX
A/C Outlet Temp: 53~59 degrees MAX
Is this for R134a?
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Old Jul 11, 2013 | 10:33 PM
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Yes this is for R134A, why?
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Old Jul 12, 2013 | 12:10 AM
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Just that the info I had says @ 100*F, high ~200-250psi and low ~50-55psi. But don't recall where I got that.
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Old Jul 12, 2013 | 12:23 AM
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The specs for the 1996 model vs the 2007 model differ great while still using R134A. My burb calls for much lower pressure readings vs the 96. This data was pulled from All Data A/C Performance Test using: 1996 K 1500 Suburban 4WD 5.7L
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Old Jul 12, 2013 | 3:58 PM
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Ok after doing the test and discovering the following readings, what does this tell us I should do next to get the AC working again?

Temp 100
Humidity 41
AC temp in degrees at vent after 3 min @ 2000rpm = 100
Low pressure reading cycling variation 15-47 psi
High pressure reading 50 psi but if I hold downward pressure on coupling the pressure varies by cycling at 60-110 psi
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