2nd Gen Non-Engine/Transmission New AC compressor?

[ethan.martin1989]

I'll go ahead and give the FULL story as not to accidentally leave something out. I have a 99 2500 cummins, the began to not cool right parked, or idle speeds but cool "ok" driving 65 or so plus the truck got warm not hot with a bunch of stop and go driving in town. So I figured lack of air flow threw all the coolers. I cleaned out the radiator, charge air cooler, trans oil cooler, and AC well enough that it would

 

[DavidC]

Low freon Level

Dave

 

[ethan.martin1989]

Already tried. I hooked up a 12oz can and it won't take. I thought maybe for some reason it was over filled cause I've only had the truck for about a year so I even let enough Freon out that the clutch stoped kicking in all together and it still wouldn't take.

 

[B.G. Smith]

You must be connected to the wrong port if you can let refrigerant out but not add. The low side connection is on the receiver dryer. Your problem could also be your fan clutch? bg

 

[DavidC]

You need to put a jumper on the low side pressure switch. If I remember right it is a green plug near the firewall passenger side. Jumper the two terminals and with the system on the clutch should engage which should then suck in the can of freon. The best way is to vacuum the system down, let it sit for a while to make sure the vacuum holds (no leaks) then charge the system with the required amount of freon. Overcharging a 134 system is as bad as undercharging. Back in the R12 days it was not as critical.

Dave

 

[GAmes]

I cleaned out the radiator, charge air cooler, trans oil cooler, and AC well enough that it would

Did you remove the radiator to clean it or attempt to clean it while installed in the truck? There are only about a hundred threads and posts about how to clean the radiator in a 24 valve equipped truck and the reason for having to be removed, which is a separate issue. Search is your friend.

 

[ethan.martin1989]

Yes I'm hooked up right. I don't have a way to put a vacuum on the system, but my other thought was maybe the high pressure switch?

 

[ethan.martin1989]

Yes I removed to clean, I have enough air flow to suck a bar mop/ Terry cloth what ever you know them as up in the grill at an idle it has lots of flow.

 

[DavidC]

Yes I'm hooked up right. I don't have a way to put a vacuum on the system, but my other thought was maybe the high pressure switch?

The high pressure is normally closed and opens on high pressure. Unplug it and put an ohmmeter across the terminals, you should read very low ohms, if not it is open. Same goes for the high as the low. Jumpering the two terminals should engage compressor if the switch is bad or activated.

Dave

 

[ethan.martin1989]

If the high side is open will that cause no pressure build up on the high side? My low side is 40 psi or a bit over but high side won't go over about 100psi. I think I slept in AC class when I was in collage so my diagnosis ability on them isn't very good haha.

 

[DavidC]

Both low and/or high will turn off the compressor.

Dave

 

[ethan.martin1989]

Alright, thanks.

 

[DavidC]

Dave

 

[ethan.martin1989]

I have another truck like mine that is junk that has all new ac components, so if it's just the compressor then I have a new one, or if it is the dryer or evaporator I have a new one lol.

 

[Bob4x4]

Performance Temperature and Pressure
Ambient Temperature 21° C(70° F) 27° C(80° F) 32° C(90° F) 38° C(100° F) 43° C(110° F) 49° C(120° F)
Center Panel OutletDischarge Air Temperature 5 to 7° C(40 to 45° F) 13 to 16° C(55 to 60° F) 16 to 21° C(60 to 70° F) 21 to 24° C(70 to 75° F) 27 to 29° C(80 to 85° F) 29 to 32° C(85 to90° F)
*Suction Pressure (Low Side) 241 to 276 kPa(35 to 40 psi) 276 to 345 kPa(40 to 50 psi) 345 to 414 kPa(50 to 60 psi) 414 to 483 kPa(60 to 70 psi) 483 to 552 kPa(70 to 80 psi) 552 to 586 kPa(85 to 90 psi)
*Discharge Pressure (High Side) 931 to 1000 kPa(135 to 145 psi) 1207 to 1482 kPa(175 to 215 psi) 1482 to 1862 kPa(215 to 270 psi) 1862 to 2275 kPa(270 to 330 psi) 2344 to 2551 kPa(340 to 370 psi) 2758 to 2965 kPa(400 to 430 psi)
*Note: If pressures are lower than shown, but center panel outlet discharge air temperatures

 

[ethan.martin1989]

Low side in 80 degree temp is 40 to 50 psi, high side dosnt break 100 psi...

 

[fest3er]

If the low side doesn't get sucked down to around the mid-20s (it should cycle between 23-50, thereabouts), I'd say the compressor isn't compressing. Could be the compressor clutch. The compressor in my '98 is original (as is the clutch) and still works fine.

If the compressor does engage, the system may be overcharged. If A/C works OK at highway speeds but not at slow speeds, the fan probably isn't pulling enough air through the radiators.