A/c blows cold when running, hot when idle

[JaxGator]

2007 Ram 5.7 110,000 mi.
A/C is cold while driving but when I stop at light, it blows hot. New radiator, a/c hose, recharged.
Possible problem/solution?

May be related, during cold weather, only defrost works, heater blows cold.

Thanks in advance for any input.

 

[Devildog8791]

Don’t quote me, but It might be your low pressure switch.


Sent from my iPhone using Tapatalk

 

[McBroom]

^^^This^^^
And if not it’ll be the Freon/oil level.
Does the a/c clutch cycle a lot?


The Blue Mule

 

[crash68]

Check the condenser fan for the AC, it needs to be running anytime the AC is on.
Another is to check the condenser is dirty, stuff built up between the coil and the radiator.
It's also possible the compressor is getting weak, you would need to verify with refrigerant gauges.

As far as your other symptoms, those are either blend door or the dash control that's causing those.

 

[kiloRAM]

Condenser fan. The refrigerant requires constant airflow to cool. If your condenser fan is not working, air does not move through the condenser radiator when you stop. Quick check is to run your truck without the ac on then turn ac on. If condenser fan is working, you will hear it turn on when AC is turned on when you stand near front of truck.

This happened to me in my 2004. Replaced the fan and it worked liked a charm. Dont let Chilton or Hanes repair manual kid you that you have to disconnect one of you AC lines to make the repair. There is a nice youtube video that shows how to make a notch in the fan shroud using tin snips that will allow you to mount a new fan without having to purge, open, then recharge your coolant lines.

Hope you get if figured out.

 

[HemiLonestar]

Cold when moving, hot when stopped. How were the first two responses not also condensor fan lol? No air blowing across condensor = no heat transfer.

 

[JaxGator]

Thanks for the input.

Kilo - I always thought it may be the fan. I actually tried this scenario some time ago and could tap the motor with a rubber hammer and the fan would run (sometimes). I also saw a video about replacing the fan and looked very complicated. The stealer estimated ~$400. I was trying to find out if there may be some other issue causing the fan to not operate at idle?

I suggested my wife tap the motor at red lights, but I won't tell you where she suggested I put the hammer.

 

[JaxGator]

Cold when moving, hot when stopped. How were the first two responses not also condensor fan lol? No air blowing across condensor = no heat transfer.

except no heat when moving although it still blows and still defrost works

 

[JaxGator]

Bought a fan from NAAPA and 1hr later have very cold air. Will see about heat issue when winter gets here.
Thanks to all for your input.