Heater A/C Temperature Control Issue

russellle · Oct 31, 2013

1999 Dodge Ram 1500 4x4 with a 5.9L

I am having an issue with the temperature control settings. It either blows full cold or full hot no matter what position the switch is in. A/C works great, heat works great, just nothing in between. I have also noticed that no matter what mode I select, Max A/C, A/C, face, feet & face, feet, feet & defrost, defrost, the A/C compressor always comes on. The only time it is off is when the mode selector is set to off.

Any one have any ideas?

Thanks

Bigtman07 · Nov 12, 2013

Sounds like it is in the blend door. On the 99 and up models the blend door was operated by a stepper motor and not a vacuum switch like pre 99 models. The motor is probably going bad and that it can only select one position.

As for the AC turning on all the time if its kicking on and off in all the other modes then it is working properly. The AC system is designed to run at all times to regulate system pressure and lubrication. The AC should be locked on when the selector is in MAX AC setting. Any other time it should kick on and off. You will also notice that the AC will run more frequently on the defrost setting.

russellle · Apr 7, 2014

Took me a while to get back here, but thanks for the info. I had a hunch it was the blend door, but wasn't sure. I will look into that. Also thank you for the info about the A/C compressor. Good to know that it's actually working the way it should.

ccava · May 20, 2015

ac/heat temp issue

Russellle,
Could you please respond if you used this info and fixed your issue with your truck. I purchased a 1999 Ram 2500 Cummins two weeks ago, and I am experiencing the same exact symptoms with it. Thanks.

Heater A/C Temperature Control Issue

russellle

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Bigtman07

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russellle

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ccava

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