Poor tired a/c fan?

Last summer I bought a heavier horse trailer and needed a bigger, badder truck to pull it with. I finally found a 2004 Dodge Ram 3500 (4 wheels, not 6) 4x4 diesel truck. I am very happy with it except: When I have pulled for about 1-1/2 to 2 hrs, the a/c fan just quits blowing. I turn it off and crack the windows for 10-15 min and then it will come back on full force. For awhile. Then it quits again, etc, etc. I haven’t pulled that long in cooler weather yet, but would guess the same thing would happen. It doesn’t seem to be the a/c, just the fan. Of course getting to the garage in middle of this non-activity isn’t possible and I just get blank looks when I describe the problem. Any ideas?

My guess is that it isn’t the AC fan but the air conditioning evaporator cool is icing up. When this happens, the air flow from the AC fan is blocked. Turning off the AC allows the ice to melt and the airflow is restored. To test my theory, turn the controls to vent but not AC. If the fan keeps blowing air, the icing of the evaporator is the problem. You need to see an AC shop and have them check the refrigerant pressures. Your system may be undercharged.

I agree with Triedaq that this could be an evaporator icing problem. The truck is roughly 10 years old and can be reasonably expected to have lost a little refrigerant over the years.

I agree with @Triedaq as well. This is a common problem where I live especially in high humidity.

@missilman–Thanks for agreeing with me–I needed someone to agree with me today. I wanted to go to a football game and thought the temperature of 60 degrees outdoors was just fine. Mrs. Triedaq thought it was too cold to sit out and watch the game. I ended up taking her out to a restaurant to eat instead.

No problem @Triedaq and tell Mrs. Triedaq that people in Alaska go watch soccer and football games when there is ice on the field. It’s just a matter of dressing properly. My wife and I promised our great nephews that we would be at every game and we were. Actually…ice on the field is better than mosquitoes any day of the week.

We drove to all the games in a motor vehicle. This was added for @cdaquila to keep the automotive theme going.

Does this have a variable speed fan, or a fan that has 3 or four speeds. Although this was on a Jeep Grand Cherokee, I’m pretty sure the actual part was the same as Dodge. I have seen the wires to the variable speed controller start melting the connector at the controller causing these exact symptoms. The controller is located under the glove box at the fan housing. If these wires get real hot to the touch and wiggling cuts the fan on and off you found it. The local Dodge/Jeep dealer sold a kit with new wires and connector (mopar part# 1-05102406AA) that could be spliced in. It worked for me. It may be completely different on your but this is at least easy to check.