AC problem in highway

[VolCTD]

OK, I've read thru every AC tread I can search on here and can't find an answer. The AC works fine around town, blower works fine, recirc door works good but when I take a longer trip out on the interstate say 30 minutes or more it starts acting up. I run it in "MAX" (recirculate) mode and it will suddenly turn warm and the blower doesn't seem to be blowing as hard. Yesterday I switched it back off of MAX and it started cooling again. I've had it stop cooling for 30 minutes or more before and after stopping for lunch it started working again.



This morning I tore into the dash and the recirculating door seems to work got and so does the fan motor. I pulled out the resistor block and checked it but couldn't anything good or bad with it. The air runs cold when it works properly.



I did notice one time the reciculator door stuck in the middle position once but worked fine after switching it on and off again.



We leave for Florida Friday and I need to get this resolved fast!



Thanks,

Bill

 

[SWithrow]

I went down to my local parts store a purchased a can of refrigerant to recharge mine last summer and seemed to fix my luke warm problem.

 

[B.G. Smith]

Your AC is icing up. Ice forms on the evaporator and blocks the air flow which makes it worse. You could be a little low on refrigerant, the clutch cycling switch could also be defective. Dodge started insrtalling a thermistor on the face of the evaporator to prevent this but I don't know what year it started. Running in the recirculating mode may increase the icing as inside air which is cooler is going across the evaporator as opposed to outside warmer air. bg

 

[DavidPratt]

I had the same problum after i tried everything i set the gap on theac clutch to about 11 or 12 thousanths buy moving the washers behind te front plate only have to remove center bolt it was easy and now works great when at high rpms mine was not iceing up i thought it was i changed driers oraface and recharged as it should it was the clutch

 

[BGlidewell]

Your AC is icing up. Ice forms on the evaporator and blocks the air flow which makes it worse. You could be a little low on refrigerant, the clutch cycling switch could also be defective. Dodge started insrtalling a thermistor on the face of the evaporator to prevent this but I don't know what year it started. Running in the recirculating mode may increase the icing as inside air which is cooler is going across the evaporator as opposed to outside warmer air. bg

this is most likely the problem IMO.

 

[VolCTD]

I'd agree too. I added a can of R134a last night so we'll see if that helps on Friday heading south. It was a little low, around 25psi so I took it up to 40-45psi when it was 90 outside. If that doesn't fix it I'll look into the clutch sensor when I get back.



Thanks for all the help and suggestions.

Bill

 

[RDeFayette]

A/C thermocouple sensor on the evaporator is not working. Keeps the A?C runing max cold all the time not allowing any ice that forms on the evap. to melt thus blocking the flow of air. The problem is probably worse when it is more humid out isn't it. You're probably also getting alot of moisture blowing out of the vents just before it finally quits blowing.

When you stop the ice melts and she'll start working again everytime (guess on my part).

Replacing the thermocouple/sensor has fixed 3 trucks I had/do have.