Correct. However, on mine it would not do anything (through defrost or any setting) when the vacuum lines were disconnected. Definitely wasn't thinking right after 38 hours straight of no sleep

 

Finally got time to start on this problem today. Either the blower resistor is shorted or the switch itself is shorted. I can put a new fuse in with the plug "off" the blower switch and it doesnt blow. Plug it to the switch and it blows. Took the blower motor out. cleaned it straightwired it to the battery and it blows just fine. So gonna get a new switch and resistor and go from there. It is nothing to do with the vaccum. As far as the operation of the fan. However, it probably does have a vac problem somewhere because it only blows out the defrost vents. Which really is just fine with me as long as I can defrost the windows thats ok.

 

Well, it is important to read all the posts on the forum! My heater blower on my '97 XJ went intermittant. Would blow at cold start, then drop to about a "1" fan speed.

I dutifully went about it all backwards. First replaced the blower resistor--No change. Then replaced the blower relay -- No change.

Then read that if you whacked the blower motor housing with a hammer, and the fan came on, you need to replace the blower motor itself. Yup, whacking causes it to work for a little while, then quits.

New blower motor ordered, so hope it is the deal! Should have started with the motor itself first I suspect.

 

I recently redid mine on a 1995. I figured I would do it once and replace everything - picked up the blower motor, switch and resistor for $82.00 shipped from Amazon. It took me two days as I was stupid and did not remove the dash bezel and tried to install the switch around it. I ended up bending one of the contacts for the heater selector harness. Once I found and corrected that issue, everything works perfectly. No more burned out resistors, squealing/dying motor and plenty of heat!

 

yeah honestly i chased my heater for awhile with the switch and resistor, my heat intermittently worked and whatever speed it wanted. I got junk yard ones though that looked newer. My switch was melted and the resistor looked bad, I tested my blower motor like you did and it worked.

it all really turned out to be the blower motor though cause when its in circuit it draws too much current and screws everything else up. its was $27 at autozone for me with a lifetime warrenty and my heat has worked great since

 

I have the same prob. ( blowing fusses ) did you figure out what the prob. was ?

 

the problem is most likely your blower motor is worn out and drawing to much current... like i already stated above. do not put a bigger fuse in, that can cause fires.

its easy to change, pass fire wall round black thing, $27 at autozone.

 

thats what I thought too , got one pluged it in but didnt mount it , still instintally poppes fusses.
I've tryed a blower motor and resistor to no avail , still poppes fuse
Help Please .