2002 Dodge Ram 5.9l V8 automatic

Ok here goes. At idle my A/C blows warm air not completely hot, but luke warm (a hint of cool air). When I go down the road it gets cold like it is suppose to do, but when I sit at traffic lights for a long cycle it starts to warm back up again. The compressor will enage and disengage back and forth continuesly at idle. It will not kick in and stay on for more than a 5 seconds. First thought was low on refrigerant. I checked it and the pressure was actually in the red zone on my gauge. Need some help troubleshooting before I take it to a shop. I have the capabilties to discharge and recharge the system, but don't know alot about how to troubleshoot. Any help would be appreciated.

 

How's the condenser fan look...is the fan engaged? You''re getting high pressure on the low side?

 

Sounds like the condenser fan is not working and the compressor is kicking out on high pressure.

 

100% certain it's the AC condenser fan shot.
They have electrical brushes in the fan motor, which wear out over time.
The fact that the AC blows cold when your moving down the road and the ac condenser radiator is being cooled by the moving air then at idle the ac blows warm, points directly to this problem.
Do a seach on AC condenser fan.
You should see my and other members posts on how we solved it without discharging the refrigerant.
Al.

 

One other thing to consider in this, make sure the condenser "coil" or radiator is clean and clear of all debris--bugs usually. Best way to clean is to pre-soak the coil with a typical soap and water, then using a pressure washer, clear the coil. Not too much pressure as this can bend the fins over.

The condenser fan should be running ALL the time that the A/C is energized--in other words, the fan should not cycle on and off.

 

The condenser fan is not kicking on at all. I will go with that, I had a problem a month or so back with a mouse/rat chewing my injector wire, I will trace that back first than start with replaceing parts, fuses, then fan motor. Guys I want to say thank you. I will post when I get it resolved or with any more questions. Oh the condenser coil is clean of debri.

 

Nice one.
As suggested earlier, whenever the AC is on including the de-frost mode on your windscreen defroster, the AC condenser fan should be running and strongly as well.
When the brushes are worn in this motor, the torque behind it is minimal to say the least and the fan, even though it appears to be turning, isn't effective at all at pulling cooling air through the condenser radiator.
Al.

 

Great news I chcked the elec. plug for power none there. Checked at the relay and no power there, but had power at the 25 amp fuse. The fuse was blown. Replaced it with another 25 amp fuse and now it is cooling great at idle. I added some refrigerant to it. It was a tad bit low. Thank you guys this site is great.

 

Nice one.
The site has just saved you a packet of money.
This is an great p[lace for tips.
Al.

 

I was gonna say low refrigerant. My Exploder was way up in the red because there was just "air" in there that was expanded causing over pressure. Anyways, I added 2 full cans and it is right in the blue.

FYI, when your compressor kicks on/off, that means your low on refrigerant. There's a saftey switch that shuts it off if it senses low refrigerant. Mine did the same thing. Prob the kicking on/off blew the fuse.