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Air conditioning failure

Tiny
YOSHII
  • MEMBER
  • 2012 RAM 2500
  • 6.7L
  • 6 CYL
  • 4WD
  • MANUAL
  • 87,000 MILES
I have no pressure when I turn on my air. No heat or AC. I have replaced the blower fan and relay under the passenger side and still nothing. It still makes cold air while driving down the highway but only at the pressure from outside air. Is there another relay in the dash? I do not know what I am missing.
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Sunday, August 26th, 2018 AT 5:26 AM

6 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good morning.

There is a blower resistor that controls the blower motor. It is under the dash passenger side. Verify power to the resistor. It is a very common failure.

Roy

1. Disconnect and isolate the negative battery cable.
2. Reach under the passenger side of the instrument panel and disconnect the HVAC wire harness connector (4) from the blower motor resistor (3).
3. Remove the two screws (1) that secure the blower motor resistor to the HVAC housing (2) and remove the resistor.
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Sunday, August 26th, 2018 AT 6:49 AM
Tiny
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I took it to a shop to help me since I did not know how to test the relay and four prong fuse. The blower motor resistor under dash is new since I originally thought that was the issue. The mechanic told me when he jumped the relay under the hood that the fan kicked on and that meant the switch in the dash was bad. Unfortunately the switch is on back-order until October at the earliest. I guess my next question would be how to jump the relay and if that would hurt anything to do so I can have AC?
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Monday, August 27th, 2018 AT 1:29 PM
Tiny
ASEMASTER6371
  • MECHANIC
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You better have them re check. I attached the diagram of the system. The control side of the relay is controlled by the TIPM or totally integrated power module which is the fuse block.

I am afraid his repair will not work on your dime.

Roy
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Monday, August 27th, 2018 AT 1:43 PM
Tiny
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Thanks for the reply. So you are thinking it is something on the fuse block and not the AC control on the dash itself? The only reason I did not question is they have over 200 on back order of that part so it seems it has been a problem for Rams.
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Monday, August 27th, 2018 AT 1:53 PM
Tiny
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Extra information, he was telling me by jumping it and the air turning on it meant it was not getting a ground which is what made him think dash switch. Anything electrical I struggle with. I am guessing I am going to end up having to go to the dealership if I am having to pull the entire fuse block.
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Monday, August 27th, 2018 AT 2:07 PM
Tiny
ASEMASTER6371
  • MECHANIC
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He just connected the load side. He never verified the control side.

He jumped the gun.

Roy
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Monday, August 27th, 2018 AT 2:09 PM

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