ac compressor not cycling on/off ice buildup
 

Ok so 2 compressors and 2 shops totalling 1700$ .. still cannot run my ac. 2003 dodge ram 3500, 5.9. 560k miles.
Replaced belt, compressor, orifice tube, receiver/drier and condensor.
After running for an hour or less all lines are covered in ice and airflow is next to nothing. Currently running the truck with the fuse pulled for ac clutch because the compressor does not turn off even if I turn the ac off on the dash. Shop admitted they did not check to see if compressor was cycling on or off before sending me out the door. Suggested I look into replacing evaporator temperature sensor.
Any suggestions at all would be very much appreciated. I've spent a lot of money and still can't use the ac. Shop that did the work is 500 miles away and I get the feeling if I go back there they will just play "pick a part" and charge me for the privilege of guessing. :( have little down time to figure this out before going back on the road to 100+ degree Temps in texas. Please HELP!

I had the EXACT problem 2 years ago. sad to say, the dodge dealer and lots of $$ didn't fix it either, as well as an A/C " specialty" shop. it took a chevy dealer. lol they told me there is some sort of a sensor that controls the a/c in front of the engine. It got replaced and the dodge dealer had to " re-learn" the sensor. Good to go now.

From picture it looked like both the high side and low side were frozen.
A/C clutch locked up or the evaporator temp sensor defective?
It could be the A/C Control head or the ECM since compressor ran even when A/C off.

A/C Control head posts the A/C Clutch request message on the Bus.
ECM reads the message and then sends the A/C Clutch Control signal to TIPM.
TIPM outputs power to clutch to run compressor.

Start looking from here.

What sensor was it that you ended up replacing? Can you be more specific? Thanks.

Thanks for the replies. I'm into this for 1700 bucks already and really can't afford to randomly replace parts at this point. I was told today to try blowing out the evaporator. Does this make sense to you? Is there any way to diagnose this??? I'm so frustrated ! Really need my ac ! Travel all over the states and use truck for hauling. I hate to be running through 100 plus Temps burning up... but can't afford any more unproductive repairs! Gypsy stuck at home!

Try to replace the pressure transducer on the high side line near the A/C compressor. Just unscrew it and install a new.
ECM cycles clutch according to pressure.

The evaporator temp sensor was installed on the evaporator fins.
ECM should cycle clutch off to prevent freezing evaporator. Hard to replace.

Yes restricted air flow through evaporator or clogged drain plug would cause freezing evaporator.

How about this????????
This was your real problem if it's true.[dummy]

Try look at or replace the A/C Clutch relay.
The power contact on the relay may stick ON all the time.

Thank you so much for taking the time to reply!

Ok, so yesterday replaced ac clutch relay at fuse box, switch on line near compressor, and the control module in the cab. Still does not turn off when turned off in cab [verymad][duhhh]
Can anyone tell me how to access that evaporator temp sensor? Where is it located? Is there anything else we can try?
Headed to texas .. still no operating ac.. :(
Thanks again for all the tips.
One HOT Gypsy.

Forget about the evaporator temp sensor now.
Have to do more troubleshooting on "the clutch was engaged when A/C was OFF".
Without fixing this you are going nowhere.

http://www.rambodybuilder.com/2004/d...42/8W-42-7.pdf
05 has the same diagram as 04.
ECM controls the clutch by grounding the A/C CLUTCH RELAY CONTROL signal, after receiving the A/C Clutch request from the A/C Control head.
Possible issues:
The wiring from ECM to IPM clutch relay was shorted to groung.
ECM failed to control the relay.
A/C control head failed remove the request for A/C clutch.

It's an 03 ... thank you so much for your help. I'm on the road but I have a few good mechanics that can better help me w this information. I've found out with this truck that it's almost always wiring issue. Now to track it down without spending another 2 grand!!

I have a similar problem on my 03 after about 1/2 hour of driving the air freezes up and if I turn the ac off it will thaw out and work again but my compressor clutch does disingage if I turn the ac off. as I say the ac works fine untill it starts to freeze up then if I turn the ac off untill it thaws and then I push the button and it works again for a while. The drain tube is not clogged as if you let it idle with the ac on the water runs out of the drain tube but the compressor does not cycle. Any Ideas ?
Jim O