I have a 2001 Dodge Ram 1500 5.2 and yesterday my heat and air started only blowing on high .. What could cause this ?
Please email me at coonhound130@yahoo.com as I will only be able to check my emails from my phone due to moving this weekend , I will not be able to get back on the forum for a few days . Thanks

 

I have the same problem and it would help if someone could post a reply.

 

Check the resistor block for the fan control. It is mounted in the heater box, close to the fan.

 

He said E-mail him!

 

This is caused by the blower motor resistor. The blower motor resistor works like a volume *** on a radio, If it gos bad you only have the high speed.

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1.Disconnect and isolate the negative battery cable.
2.Reach under the instrument panel near the blower motor (5) and disconnect the wire harness connector (2) from the blower motor resistor (4).
3.Remove the two screws (1) that secure the blower motor resistor to the HVAC housing (3).
4.Remove the blower motor resistor from the HVAC housing.

 

yep, the resistor is the issue, it needs to be replaced, and is very simple, but when you do, also drop the fan motor out and clean out the squirrel cage, something stuck in the cage is the cause of most of the resistor failures, i have found all sorts of things in them, napkins, ammo, leaves, sticks, dead critters....

 

Friend had same issue in his ford ranger.
It was all rusty.
So we used Navel Jelly to clean it, it worked like new afterwards.
Just don’t get it on anything other than the rusty part of the resistor, not sure what it would do to the board.
Also toilet bowl cleaner is good for removing rust on parts too.

Dave

 

I've also read on hear that you can fix the resistor yourself with a soldering iron... the new ones are like $50 if I remember correctly... I have the same issue