2001 Durango 4.7L . Bought it a couple of months ago with a bad compressor. Replaced with a new compressor and drier, pumped the system down and it held a vacuum, no leaks. Charged the system to spec, (right amount of Freon, good readings). Not great A/C but in specs. Now that it is hot, (Texas), it just isn't getting it done. Readings at idle 46 low, 225 high, 68 degrees at the vent, 100 degree day. Based on the guidelines on the top of the forum worst case I should see 60 at the vent. Electric fan engages, clutch fan spins, and with the engine off it doesn't free wheel. Interior blower motor spins on all 3 speeds. Not sure how much air it should push on the highest setting, but it doesn't exactly blow you back in the seat like Fords or Chevys. One last thing, I misted cool water on the condenser and the high side pressure dropped to about 150. Any help would be appreciated.

 

Maybe the pressure is to high? In my 00 4.7 I had it at about 45 low side , dont know about high dont have a guage. Mine wasnt cutting it in SC , so I tried letting some pressure out of the system down to 30 low side and it works much better.

 

when you take these readings, are you holding the engine to 1500 RPM???

 

That was at idle. I re-took the readings this morning @ 1500, 85 degrees. Low is 34, High is 220, vent temp is 60.

 

(from the A/C Sticky)

so from this chart(simple interpolation, should be close enough)
Outside-----low side-------High side------Center vent temp
80 F ------30-40 psi ---190-220 psi ----43-48 F
85 F-------32-40 psi ---190-222 psi ----43-49 F
90 F ------35-40 psi ---190-225 psi ----44-50 F

i assume you are measuring it at the center vent so if thats the case you are about 10F higher than it should be, you could have a dirty evaporator, and i have also seen some people insulate the a/c lines in the engine bay (the cold lines, low pressure side, going into the evaporator) to keep the engine heat from being absorbed by the refrigerant, something else to try

Also, running the fan at higher speed will increase the vent temperature some bc the air does not stay in contact with the evaporator coils as long, so less heat is absorbed from the air.

 

I did put some insulation on the hoses closest to heater lines and other hot points, (ridiculous routing). Is there an easy way to check or clean the evaporator? Would adding another fan across the condenser do any good? It's going to be 105 or so here today, so getting that 10 degrees means a lot. Thanks for the info.

 

is your condenser clean or is it packed full of dust and dead bugs? if its packed full cleaning it out could make a HUGE difference, i have never heard of adding an additional fan to help with it, the 2000+ trucks already have an additional electric fan which comes on w/ the a/c check to make sure that is working maybe.

 

I checked the evaporator through the sensor hole, and it has a ton of dust on it. Not sure of an easy way to clean it, so I'm open to suggestions. I have cleaned the upper 2 thirds of the condenser out, I'll have to get to a car wash and use a wand on the lower 3rd. It doesn't look bad, but every degree I can get helps. My fan is working, but when I mist cold water over the condenser I get a significant drop in high pressure. Aftermarket AC sites usually say this is due to poor airflow. Anyway, biggest bang for the buck looks like evaporator, now if someone can get me a tip that keeps my dash intact, I'm golden. Thanks for the help.

 

check into using the intake for recirculating the air its in the footwell on the passenger side, may or may not work but its worth the time to look

 

Just to give those interested an update. I bought some of the foaming evaporator cleaner, (safe on plastics, and filled up the air box via the sensor hole. I also picked up some of the cork tape that a/c guys use for reefer trucks. This is the same stuff the big 3 used back in the day. Anyway, @93 deg. my vent temp is 58 at 1500. Still not in spec, but a few degrees closer. Usually I get another 5 degrees or so when I drive so maybe that will get it in spec. In any event, probably going to drop the $400 for ceramic window tint to help the overall heat load. Thanks for all your help.