Expert: Roland Finston - 7/24/2011

Question
QUESTION: In my '00 Chrysler grand voyager SE with a 3.3 liter v6 flex fuel, the interior fan for the front A/AC,heater has only low flow.  I have looked at it my self and also had a mechanic buddy look at it, we belive it is a vacuum issue, mainly due to a vacuum cap that rolled out from under the dash shortly following the fans malfunction, the actuators work properly and it switches from heat to cold with out problem but I have no control over the fan even if it is turned off, while driving down the road it works, while idling it is not even blowing hard enough to feel, from time to time you can hear the fan blow but no flow out of the vents.  I have my dash torn apart but still don't see much with out completely taking the entire dash out. Any ideas...

ANSWER: Before getting into the details, is this a standard type control panel or a three-zone automatic temp control type of unit? I assume you checked fuse #10 in the power box, just inboard of the blower motor relay, and also that the relay clicks when you ask for the blower.
Roland

---------- FOLLOW-UP ----------

QUESTION: No, I have not checked the fuse due to it still blows just not as well as it once had, but I will check them.  And it has a standard control type with a separate operation switch for the rear, heat and cold with two zones on for the driver and one for the rest of the vehicle

Answer
Hi James,
If it has 5 different fan speeds but you only get one slow speed output no matter what the blower switch is chosen for, and the blower relay clicks positively, about the only possibility I can see is that the blower motor is weak/binding or that there is some sort of poor connection between the relay output and the motor/motor control switch. Pull the plug at the blower motor and check that you have the full 12v on the black wire at the blower motor plug and that when you have the speed set for 'high' that there is a good ground (0 resistance) on the dark green wire of the motor plug. Then if you change the speed setting you should see an increase in that dark green wire's resistance to ground as you change the speed setting lower. If that checks out, then the motor has to be binding up or the brushes/armature are compromised.
Roland
PS On the wire colors I am referencing the '02 manual. If those are different on your '00, then check the dark blue wire for 12v, and check the resistances shown on the black/tan wire, both at the motor plug which are the ones shown in the '98 manual. I don't have the '00 manual but I believe the wiring in the '02 applies to your '00. Let me know if I'm wrong.

If by chance you have the ATC type unit, and has multiple fan speeds compared to the 5 of the conventional system, then I suspect that your problem is the blower motor power module which is a solid-state device that puts out the multiple voltages to run the blower motor. When they fail it is often the case that the blower will run at only one speed and not be controllable.