I have a 2002 4.7 with dual AC. The front is blowing at 64F, and the rear is blowing at 97F. The full length of the line running from the compressor to the firewall is cold, but the section that splits off at the T joint and the section under the Durango that goes to the back is warm.

Is this a symptom of low freon? Can this be solved by recharging with a can of A/C Pro Cold or similar?

 

May have to get inside the back and check the blend door. It may be stuck or broken for the heat. If you search it, that topic has been discussed numerous times and is in the faqs sticky.

 

I know its not the blend door. It was broken, so I removed it two summers ago, and then it only blew cold.

 

It could be the expansion valve for the back. They have separate ones for the front and back. The front should be in the 40s though, not 64.

 

If it was the rear expansion valve, would the line be cold until that point? Because its not.

Does the 64F air suggest that I'm low on freon?

 

The line should be cold all the way to the expansion valve. How cold is the front line? It should be pretty cold and have condensation on it.

 

It is pretty cold and it does have condensation on it. It goes immediately from cold to warm at the T joint where the rear line begins. The T joint is vertical.

 

Ideally you want a 35 degree coil. The exposed suction lines will probably read about 50 to 60 degrees if it's charged correctly. If it's cold, and then suddenly changes to hot, That's probably where your orifice is at and it's most likely clogged.

 

That's what I'd think too. I was under the impression that our ac systems used expansion valves instead of orifice tubes, but 01-03 is probably different.

 

The pressure in the system was lower than it should have been, so I bought some freon and added it until the pressure reached the normal area. This brought the front AC temp down to 57, but still no change in the rear.

So I guess thats substantial proof for a clogged line? If so, is that a DIY job to fix or one for a mechanic?