1999 jeep grand cherokee heater fan quit. 40amp fuse under hood good. both wires at motor test hot. motor turns strong when wired direct to battery. now what?

Do you know how to test automotive electrical circuit's , looking at a wiring diagram so you know what all is involved in the blower motor circuit . Using a DVOM - digital volt ohm meter to test the circuit . Free wiring diagram's here http://www.bbbind.com/free_tsb.html Enter vehicle info. year , make , model an engine size . Under system click HVAC ,then under subsystem click on HVAC controls . Click the search button then the blue link .The thing's that could be wrong , blower motor it's self , the blower motor controller for automatic climate control , a blown fuse -but fuse's don't just blow for no reason - short to ground maybe ! 40 amp fuse #1 in the under hood fuse box . Blower motor resistor block if your vehicle has manual climate control .
Test And Replace Blower Motor Resistor Chrysler Town Country Caravan

lead burned through
that's easy
using the wrong fuse size
and the feed is shorted,
the correct fuse prevents the burned wires.

here are the HVAC pages
http://www.jeep4x4center.com/knowledge-base/index.htm?utm_source=cj#service

lots of things can short. in cars. (topic Hvac)

• the wires.
• the connectors
• the HVAC motors (actuators)
• the blower.

if you had stated the exact wire color and what it connect to exacty
we can state who shorted.

Fuse 1 , 40amp runs the blower. dark green.
Fuse 20 , 10amps runs others.
Fuse 7 runs zone control,,,10A and all 4 damper motors actuators.
see 8w-42-6 pages.

ok you have your FSM and now can find who connects to what.

Have you checked fuse #1 in the box under the hood?

the fan relay is located under the passager side headligh.t this relay controls the a/c and raditator fans. all jeep and chyrlers garge opens a 4"x4" hole to get to it; this prevent them from removing the front bumper. you can do this i open the hole and replaced it myself. the light will cover the hole back up.

The fan relay is likely shorted and keeping the fan motor energized. To check this you can remove the relays from the fuse panel. Remove the cooling fan rely from the underhood PDC. Check position 10, 40AMP...



Good luck (remmeber rated this post).

If it doesn't run on any speed then check fuses and relay's under the hood in the power distribution box,if all are good then use a test light or volt meter on fan motor wires with fan switch set on high,if you have power there then replace fan motor,if the fan works on some speeds and not others than check the fan speed control module,it is located in the air duct on pass side below glove box.

"...wires to fan test hot." But what is the voltage? Since the Fuse and Motor is good, and there is voltage (unk strength) to the Motor; this only leaves the Blower Motor Resistor. Does the Fan work on High Only? Then it is definitely the Blower (Fan) Motor Resistor.

hi
in the engine compartment there is a fuse box beside the battery, if you locate the fuse for the heater remove it then turn the ignition on and re-fit the fuse, after a few seconds you should hear the actuators moving (resetting themselves) if not remove the glovebox and you will find the drivers side actuator held in place with 2 phillips screws, remove and thes with a 9v battery and two pieces of wire the motor should turn. then reverse wires and motor should turn the oposite direction, if it doesent its your actuator and if it does the problem is the fuse or the switch panel.
hope this helps

fan comes on when a certin temp is met.check the fan motor it self by straight wiring the fan motor with the engine off. do this by finding the wires to the fan motor and stripping the wires back and connecting the wires to the battery one to hot and one to ground if the fan comes on you have a thurmstat problem.if it dont come on the fan is bad

Your fan seems to be drawing way too much current, common with fan motors of all kinds when they are going bad. It will still blow, but hot wires and blown fuses in the normal circuit indicate you have an excessive load in the circuit. Fan motors create this condition regularly, but are often ignored since they are "still blowing."

Here's a cheap, easy way to test my theory:
Try a new fuse, the proper amperage, but leave the blower motor unplugged at the blower itself. That will tell you in a few rides if the blower was the culprit. (Which it most likely is.) I bet your #20 fuse will stop blowing and no more smoking pink wires! Hope this helps. Remember, blower motors are cheap, traffic tickets and dash fires are not. The blower motor draw is the logical thing wrong with this picture. Good LUCK! TT