2002 Dodge Dakota 3.9L. Whenever I’m driving with the AC on, my vents seem to cut out and random times, and stop blowing air. About 20 seconds later, the air will resume. AC is cold and when it does work, all the fan speeds are fine. It does this at idle, and while in motion. Could this be a bad blower motor resistor?
When the AC stops blowing out of the vents, check and see if it is blowing out of the defrost. I owned a 98 Dodge Ram that would do this. The AC modes were vacuum operated, and a one way check valve in the vacuum lines (under the hood, near the cowl) had failed. In my case, though, the AC would usually switch from vent to defrost when the engine was under load, not at idle. I’m not sure if the ac mode selection still relied on engine vacuum in 2002, but it’s something to look into. The check valve is super cheap.
Thank you for the response, however I’m having trouble tracking down a check valve that fits my engine.
Does the blower work at the “HIGH” speed setting? Usually, when a resistor goes bad, one (or more) of the low fan speeds does not work. If it works at high speed (and not low speeds), then you probably have a bad resistor, otherwise,a vacuum problem. My 1982 Toyota Cressida also has a vacuum operated heater control, and like Scrapyard_John suggested, this could affect the temp, and/or air distribution.
It may not operate like the 94-01 Ram. The check valve on those was on a vacuum line near the firewall, sort of above and behind the engine.
Yeah I should have mentioned that in the initial post. When the airflow stops, I can turn it to the highest speed and it will resume. That’s what led me to believe it was a resistor. Probably gonna throw a resistor at it and see if that fixes it.
Ok, that’s probably your issue then. The check valve only assists with the mode control (floor, vent, defrost).