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Discussion Starter #1 (Edited)
Hi All,

It's getting hot here in GA (90-100 during the day with 75+ humidity) and I noticed the AC in my truck not cooling as effectively as it normally does. Hooked the gauges up to find out that the low side is at 6psi and the high anywhere from 210 - 250 psi (all at 1250 rpm). Evaporator core inlet lines are ice cold after the orface but warm to the touch on the return side. Filled it until the low stabilized at about 35psi (the high side the same as before). The return lines are now cooler than before but I'm afraid to keep adding r134a to the system without some insight from others. I have cleaned out both the condenser and evaporator coils. Any advice or ideas on what to do next?

Also have an early 99 7.3 which turns both the evap coil inlet and return ice cold almost instantly after startup.

Ethan
 

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Your orifice tube screen is almost plugged
Do you have the little vacuum valve in the heater hose near the firewall?
if so, then zip tie it to the closed position, you will not need the heater till the weather cools off
this should help your AC cool some better until you can replace the orifice and dryer
 

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Discussion Starter #3
Thanks for the reply Hydro!

Yes, the vacuum valve is zip-tied closed to prevent coolant from going to the heater core. After filling the system yesterday (probably 1/4 of a can) the AC was blowing 32 on my vent thermometer at 95 degrees for my 300-mile trip (all highway at 75+). We had checked and filled the system about a year and a half ago when I first got the truck and it worked great all last summer. I'm thinking there may be a very small leak in the system.
 
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