I'm getting my truck ready for a summer vacation trip and the last time I had it out In February I noticed the AC duct temp was not as cold as other times. I checked the system with AC pressure gauges and had a digital thermometer for temp readings. Now with an outside air temp of 71°F The low side pressure reading was 35 PSI and a high side pressure of 225 PSI with a duct temp of 52°F at idle and 47°F at 1300 RPM.
The 134A pressure chart says that at 70°F low pressure should be 35-40 PSI with a high pressure reading of 145-160 PSI. Seeing that the trucks low pressure was correct, albeit on the low end of the specification, the high side pressure was 65 PSI to much indicating a slight blockage or a poor operating orifice metering valve. With the truck's AC system being 25 year old it was time for some maintenance to get it up to peak operating performance.
I replaced the high-pressure line from the condenser to the evaporator which comes with a new orifice tube in it. I also replaced the accumulator. I evacuated the system with a vacuum pump for 1 hour and then left it in a vacuum for a half hour to check for leaks with none found. The system was recharged with 2 pounds (32oz) of 134a and 2oz of PAG 46 oil for the replaced accumulator. The post repair test readings at idle were outside air temp 67°F, low side pressure 25 PSI, high side pressure 140, air duct temp 36°F.
So, for maximum summertime cooling test the truck's AC system and repair as needed.
I'm getting my truck ready for a summer vacation trip and the last time I had it out In February I noticed the AC duct temp was not as cold as other times. I checked the system with AC pressure gauges and had a digital thermometer for temp readings. Now with an outside air temp of 71°F The low side pressure reading was 35 PSI and a high side pressure of 225 PSI with a duct temp of 52°F at idle and 47°F at 1300 RPM.
The 134A pressure chart says that at 70°F low pressure should be 35-40 PSI with a high pressure reading of 145-160 PSI. Seeing that the trucks low pressure was correct, albeit on the low end of the specification, the high side pressure was 65 PSI to much indicating a slight blockage or a poor operating orifice metering valve. With the truck's AC system being 25 year old it was time for some maintenance to get it up to peak operating performance.
I replaced the high-pressure line from the condenser to the evaporator which comes with a new orifice tube in it. I also replaced the accumulator. I evacuated the system with a vacuum pump for 1 hour and then left it in a vacuum for a half hour to check for leaks with none found. The system was recharged with 2 pounds (32oz) of 134a and 2oz of PAG 46 oil for the replaced accumulator. The post repair test readings at idle were outside air temp 67°F, low side pressure 25 PSI, high side pressure 140, air duct temp 36°F.
So, for maximum summertime cooling test the truck's AC system and repair as needed.
Happing motoring,
Dan