No AC/Heat/Vent from blower

90 MJ 4.0L, My blower motor is not pushing any air in any position- fuse is ok- is it likely a vacuum leak? I checked the problem vacuum areas (at the battery and the front bumper) and have not found anything. Any other potential areas? I noticed that one of my vacuum lines coming from my transfer case has a black plug capping it off with FORD on it- any AMC/DCX use of Ford parts?

Would a behind the dash vacuum leak drastically effect some of the other components (i.e. running rich, loss of 4wd, etc?)

Thanks in advance!
PRL

prljeep said:

90 MJ 4.0L, My blower motor is not pushing any air in any position- fuse is ok- is it likely a vacuum leak? I checked the problem vacuum areas (at the battery and the front bumper) and have not found anything. Any other potential areas? I noticed that one of my vacuum lines coming from my transfer case has a black plug capping it off with FORD on it- any AMC/DCX use of Ford parts?

Would a behind the dash vacuum leak drastically effect some of the other components (i.e. running rich, loss of 4wd, etc?)

Thanks in advance!
PRL

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re-iterate. Is it on, moveing? or is it dead, not moveing? If its dead, and the fuse is good, its likely burnt up-a replacement deal-or the thermal fuse is history. If its moveing, but not circulateing from any vent, somethings amiss. Most times a vac leak in system will revert the blower to defrost only mode-no matter where yu want it, you`ll only get it out of the defrost ducts to the windshield.

Any vac leak, if big enough will screw with everything that requires vac- an yep, that includes 4wd on vehicles with vac connection axles in front- it can make it run rich- it can mess with the EGRs signal/map signal/ect....

If it's a '90, the blower motor may be dead. The blower on my '88 died over two years ago. Easy to replace, once Matthew Currie helped me diagnose the problem.

Ed in North Ga. said:

re-iterate. Is it on, moveing? or is it dead, not moveing? If its dead, and the fuse is good, its likely burnt up-a replacement deal-or the thermal fuse is history. If its moveing, but not circulateing from any vent, somethings amiss. Most times a vac leak in system will revert the blower to defrost only mode-no matter where yu want it, you`ll only get it out of the defrost ducts to the windshield.

Any vac leak, if big enough will screw with everything that requires vac- an yep, that includes 4wd on vehicles with vac connection axles in front- it can make it run rich- it can mess with the EGRs signal/map signal/ect....

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It is running. No 4wd, no blower, and it is running rich (poor fuel economy). When I first got my MJ the blower was iffy- like I would mess with fuses or wires near the radio and the blower would either work or not work. Then it worked fine for about 3 months until this past weekend. I did nothing to it except not drive it for about a week or so. (Maybe she's just mad?).

Not to hijack your thread....

...but the '87 I just bought had a dead blower motor when i got it. Then, one day, it suddenly "sprang to life". But only for a minute. I dealt with the cold until yetserday, got sick of it, and used my stock lug wrench and beat on the blower motor, and it came back to life!!!
(I know hitting stuff doesn't fix it, but...well it did...um...sort of..) So it works good for about 1/2 hr. or so, and then slowly loses all it's balls until it doesn't work any more, in which case i get out, kick it's ass, and get back into a nice warm Jeep. Is it the blower?

prljeep said:

It is running. No 4wd, no blower, and it is running rich (poor fuel economy). When I first got my MJ the blower was iffy- like I would mess with fuses or wires near the radio and the blower would either work or not work. Then it worked fine for about 3 months until this past weekend. I did nothing to it except not drive it for about a week or so. (Maybe she's just mad?).

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Sounds like a vacuum leak, but I can't even begin to guess where to look. Start with the tubes under the battery tray, and the "blimp" (vacuum reservoir) that's behind the bumper on the right side.

Re: Not to hijack your thread....

gupandme said:

Is it the blower?

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Sounds like it. If the lube is dried up, I've read of someone who carefully drilled a tiny hole in the center of the "nub" at the end of the axle shaft, and added a couple of drops of oil then covered the hole with tape. That'll work for dried-out lube, but if it's old the motor brushes may be worn out.

Re: Not to hijack your thread....

Eagle said:

Sounds like it. If the lube is dried up, I've read of someone who carefully drilled a tiny hole in the center of the "nub" at the end of the axle shaft, and added a couple of drops of oil then covered the hole with tape. That'll work for dried-out lube, but if it's old the motor brushes may be worn out.

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It hasan't shut off again yet, but when it does...lube sounds like may be right.
it's like it requires the force of the "whack" to get it moving...then it works fine. like its binding up on something. Eagle, thanks for the help (as always).
:rof: :looney: :rof:

Re: Not to hijack your thread....

gupandme said:

It hasan't shut off again yet, but when it does...lube sounds like may be right.
it's like it requires the force of the "whack" to get it moving...then it works fine. like its binding up on something. Eagle, thanks for the help (as always).
:rof: :looney: :rof:

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The replacement blower I put in the '88 was a used unit, and in cold weather it squeaks, in warm weather it's quiet. So the lube is probably sort of marginal. Dried lube could account for needing a bit of "persuasion" to start, but in that case I'd expect once it got spinning the friction would warm up the lube and let it keep going. If it runs for half an hour then stops, it may be that the brushes are so worn that the remaining stubs don't feed straight. The whack may jar them enough to re-establish contact, but then after running for awhile they wear enough that the contact isn't maintained.

Purely speculation.

Re: Not to hijack your thread....

gupandme said:

It hasan't shut off again yet, but when it does...lube sounds like may be right.
it's like it requires the force of the "whack" to get it moving...then it works fine. like its binding up on something. Eagle, thanks for the help (as always).
:rof: :looney: :rof:

Click to expand...

The replacement blower I put in the '88 was a used unit, and in cold weather it squeaks, in warm weather it's quiet. So the lube is probably sort of marginal. Dried lube could account for needing a bit of "persuasion" to start, but in that case I'd expect once it got spinning the friction would warm up the lube and let it keep going. If it runs for half an hour then stops, it may be that the brushes are so worn that the remaining stubs don't feed straight. The whack may jar them enough to re-establish contact, but then after running for awhile they wear enough that the contact isn't maintained.

Purely speculation on my part, however. If I could remember where I put the one I removed, I'd look it over to see if the brushes are user-serviceable. Unfortunately, I put the old one where I'd be sure to find it, and you know what that means ...

Re: Not to hijack your thread....

Eagle said:

I put the old one where I'd be sure to find it, and you know what that means ...

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It means I may find it before you do. :laugh:

It hasn't stopped working agin yet :clap: ...thanks though.

I wish i had a digicam...my front end went through the ice last night.... :shiver: Of course I wasn't prepared.

I have a 88 XJ Pioneer, 4.0, AW4, np231 and when I got it from my Dad's estate in 97 the part time light would not come on. I also did not hve working cruise control. I picked up a chilton manual then shortly later purchased all the manuals from Jeep.

I noticed vacuum leaks were listed in chilton for both systems not working. I went to my dealer and asked if there is a vacuum harness for the 4x4 system for the shift motor on the axle. The guy pulls out the part and I pay him for it. I am totally new to XJs and spend a week trying to figure out where this stupid hose goes. I finally found it, it connect to the shift motor which is directly under the oil filter then up to some metal tubes.

If you have the NP231 transfer case (part time) then go buy a new shift motor harness at the dealer, they runa bout $10.

If this is an older XJ then change the CCV system harness under the hood. There are 3 assemblies you buy at the dealer. This will give you new vacuum lines for the fuel pressure regulator, EGR valve everything else that hooks up to the intake manifold. Here an article so you can read up on the system. If you also have oil in the air box chaning the tube at the back of the valve cover will fix that problem. http://www.off-road.com/jeep/cherokee/xjtech/engine/40ltr/blowby.htm

Also pick up a new oil filler cap, they run around $3 at the dealer or your local parts store. Stant makes that butterscotch colored cap.

In 97 I replaced all those components and if make my XJ run better. They fixed my 4x4 problem, and solved all my vacuum leaks. The items in the link I gave are 50,000 mile replacement items so you are not doing anything unusual.

Like Eagle said check the vacuum lines around the battery, lots of people have problems with the acid doing them in.

If your blower motor is working and you need to look at vacuum. I understand if there is a vacuum leak the vents go to defrost, do you get air out of the defrost vents?

Also do you get the different speeds out of the fan? There is a resister assy which is used to adjust fan speed. That component could of failed.

I can explain more on any of these if you want, let me know.