About ten minutes into my trip it starts blowing warm air

RYAN303

MEMBER
2001 DODGE RAM

I have a 2001 Dodge Ram 2500 with a V10 automatic. When I start off with a cool motor my a/c works fine. Then about ten minutes into my trip it starts blowing warm air. I noticed that when my a/c in on regular the a/c clutch keeps spinning and the a/c lines ice over. When I switch to max a/c it will free spin again the lines defrost. Now obviously I can't observe this while i'm driving and when the truck is parked with the hood up everything works fine. Only happens when I drive. Any thoughts?

Sunday, July 26th, 2009 AT 7:43 PM

1 Reply

SQM

MECHANIC
6,383 POSTS

Hello,

A/C lines freezes when there is moisture in the system. This can happen due to a leak if there is a leak air and moisture can be sucked in by vacuum on the low side of the system.
This causes the liquid refrigerant to expand into a gas, forcing the temperature to drop. The moisture in the system can freeze at this point, this will block refrigerant to flow through the valve and you will get warm air thru the vents.

Best course of action would be to first detect the leak. Which can be done using a dye injected into the system. After determining the leak, discharge the system properly and fix the leak (likely replacing the O-rings) and recharge it back up.

Here is a helpful video:

https://youtu.be/4EqdrBVb0sY

I have attached diagrams for your reference.

Please let me know if you have any questions.
Thank you.

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