I have a 2004 Dodge Ram 3500 diesel. My air conditioning works great for an hour or so then it peters out. I can turn it off and wait a bit and it will work again for a while. I’ve taken it to two mechanics and they were unable to solve the problem. Anyone have any clues?
Eric

 

Evaporator core freezing up?

Welcome to DF! Moving this to third gen Ram section for ya.

 

Boom! Thanks

 

So was that the problem?

 

They should be checking the basics like pressure on the high side and low side, cond fan working ALL the time, AC clutch stays engaged, ect.

Do not take it to a mechanic though, take it to someone who is AC cert

 

when I saw your reply I didn’t see the question mark. I talked to my mechanic and it seemed plausible. Problem is that the evaporator core requires removing the dash. Minimum 6 hours.

 

Used the truck on an extended trip recently and thinking that the evaporator core was the culprit I only turned the fan on medium speed. This seemed to work. So by cranking the fan on high it was causing the freezing apparently.

 

High speed on the fan shouldn't make it worse if the evaporator is freezing up as it takes warm air and sends it across the evaporator, BUT at lower speeds the air may loose heat to the ice. If the low side line in the engine compartment is very cold headed back to the AC compressor; I would think it's freezing up. If it isn't cold, then maybe the expansion port? Not sure. I'm fighting with my 08 Ram 2500 right now with what I think is 2 issues at once on the AC. LOL.

 

I've seen crud built up on the evaporator cause freezing by restricting air flow. Rather than pull the system apart, BG Industries used to make some stuff called "Frigiclean". You drill a small hole and squirt it into the housing. It foams up inside and as the foam breaks down, the dirt will roll off.