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B. W. · 10-08-2018, 04:41 PM

Does your truck have factory A/C? If so, the correct charge (based on the '71 service manual) is 3 lbs, 4 oz. With engine at 2000, ambient at 80°, high side should be around 185 -195 psi, low side approx. 30-35 (POA, based on altitude.) discharge temp @ 38° - 41° at right hand outlet. My personal experience, I can almost always get cooler temps with a good system.

One way to confirm you have the correct charge - if your system is stock you should have a sight glass on the receiver/dryer. When the system is at full charge you should see no or very few bubbles in the glass.

10-08-2018, 04:41 PM	#6
B. W. Registered User Join Date: Nov 2014 Location: Bigfork, Montana Posts: 1,137	Re: Reading A/C gauge Does your truck have factory A/C? If so, the correct charge (based on the '71 service manual) is 3 lbs, 4 oz. With engine at 2000, ambient at 80°, high side should be around 185 -195 psi, low side approx. 30-35 (POA, based on altitude.) discharge temp @ 38° - 41° at right hand outlet. My personal experience, I can almost always get cooler temps with a good system. One way to confirm you have the correct charge - if your system is stock you should have a sight glass on the receiver/dryer. When the system is at full charge you should see no or very few bubbles in the glass.