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High fan speed speed inop, the other three speeds ok and max AC boost works for the fan speeds that work. Has the rotory swich failed or is this the resistor block failed? By the wire diagram can't tell if this is all the same *** or if the resistor block seperate *** part of the rotory switch?  

sounds like a bad blower motor resistor.  should be a seperate peice but im not sure on your car.  

I just bought a 2001 TJ.  The fan switch was the problem.  Unfortunately, the switch is only sold with the panel of 3 controls.  It cost me about $80.00.  Everything was fine for about 3 weeks.  The replacement broke too!  I don't know if the fan is causing the switch to overheat or what.  My symptom is you must put the switch between the speeds to get anything to work.  It's like the switch got too hot and came apart inside.  I have 2 settings now, off and high.  The dealership said they'd replace the defective switch for free.  

I have replaced the fan switch on mine 3 times, it is the fault of the switch itself, it is underated for the current that the motor draws.  You must also be sure that the plug on the switch has good connections, this may require cutting the wires and installing new push on connections and this time SOLDER them to the wires.  If these connections get cruddy from overheting, they will cause resistance and the connection will get hotter and melt the plastic inside the switch.  You should be able to buy that fan speed switch separately, mine cost about$15.00 at the local dealer. Hope this helps...........TLC  

It could be the blower module. It is located behind the Glove Box. The wire from blower motor is connected directly to this module that has a defect of over heating the main power connection to this board. If you remove the Module and take apart you can see the burnt connection which causes a high resistance. You can get a replacement Kit from dealer to fix the wire terminal.  

How do I find this piece you are talking about? I have removed the glove box and everything else. I replaced the switches and the wireing to the switches last yr. Now this is my last hope. I need to fix this problem once and for all.

Thanks  

wHERE ARE THE AMSWERS TO THESES QUESTIONS  

jim dandy.... these questions are several years old...

i am taking you have a similar problem.. the answer you are looking for might be on another forum thread on this site... there are thousands of threads... some with detailed answers.. some not...  if people don't come back and post the result of their research.. it just makes it hard on other people...

so lets start with year make and model...   manual ac or automatic ac...  

autozone does have some wiring diagrams... and i have a few years of them,,,,  heating and AC is not in my normal line.. but.. a better description of your exact problem ...i will take a look...

a few things...

when stuff starts melting in heater blower circuits..

the fan motor may have worn far enough that its drawing additional current beyond what the circuit was designed for.. this does happen..

its also possible for the heater resistor to fail... get shorted..  get trash on it.. so the airflow through the windings is blocked .. causing it to overheat and fail...

normally... on high ..  the resistor is bypassed and the current flows directly...

but this all depends upon which system you have...

if they offer 2 systems.. most makers  

more to come... the spam blocked has me blocked...



this is the blower resistor... you will have to copy and paste the link to see it... or copy the entire text of this answer.. paste it into an email to your self.. the links will be click able when you get your email back...

h ttp://contentinfo.autozone.com/znetcs/product-info/en/US/wl2/CR158/image/4/

this is the back of one of the heater control heads

h ttp://contentinfo.autozone.com/znetcs/additional-prod-images/en/US/wl2/SW2347/2/image/4/

here is the top view..

h ttp://contentinfo.autozone.com/znetcs/additional-prod-images/en/US/wl2/SW2347/3/image/4/

here is the blower motor...

h ttp://contentinfo.autozone.com/znetcs/product-info/en/US/sie/PM6002/image/4/

and here is the wiring diagram for the 2000 model... heater and AC controls

h ttp://repairguide.autozone.com/znetrgs/repair_guide_content/en_us/images/0996b43f/80/23/92/e7/large/0996b43f802392e7.gif

you will have to copy each link... take out the space between the first and second letter..  

Hey, WayneP...

How are you getting the links for the drawings/images on autozone.com?  I compared your links/drawings to those in my Haynes repair manual (published 2009) for Jeeps 1997 or newer, and the two drawings are different - yet similar enough to read their typical function.  I tried the magic google search, but did not get your results (Jeep parts pictures, rather than any parts picture).

Referring to one of your links: "heater circuit," your drawing's "Blower Motor Resistor Block" is separate from the motor, whereas my Haynes shows the a single unit consisting of the blower motor, blower motor relay and blend door actuator (called the HVAC UNIT - but the AC part is separate, obviously, as it has a compressor).

The image links are GREAT!  I didn't know a PVC from a DOG until I saw a picture... they really are an asset for the new guy (me).  

those are from the autozone.com... free repair info.

go to autozone.com...  upper right corner join and log in..    select your car....   when logged in.. just above where you selected your car... the words... view free repair info...   once there...  click the bottom link on the left side.. repair info again...

the wiring diagrams are usually under chassis electrical and at the bottom of that selection again..

az covers cj models back to 1955 or so...  and a lot of domestics back to the mid 60s..  

WayneP - Thank you for the AZ image and diagram tips.  

i'M HAVING PROBLEM WITH MY BLOWER MOTOR, HAVE NARROWED IT DOWN TO DIODE ON RESISTER MODUle. DO YOU KNOW IF I CAn buym diode seperate?