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Discussion Starter · #1 ·
i am replacing my tub with a yj tub; so i figured i would do the heater upgrade to the body while it is off and the body is stripped. I also had a 78 blazer and ripped the heater out of the blazer, and after taking the one out of the two vehicles it came to my attention that they where both identicall fans whats the problem here? do i have the wrong year blazer? or is the yj motor better than the cjs?
thanks for the help!! My cj should have a yj tub on in the next couple weeks!!! yeapie :)
Andy

 
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Discussion Starter · #2 ·
I'm not sure about the YJ motor, but I did just do the upgrade on my 84 CJ7 and found a couple of errors on Terry Howe's instructions http://www.off-road.com/jeep/tech/body/heater.html.

First, let me qualify my statements by saying that overall Mr. Howe did a GREAT job on his write-up... it's guys like him that may the learning process so much more enjoyable for those of us new to the Jeep world.

That being said... according to the write-up -- "Ask them for a heater motor for a '73 Chevy Blazer with a 350 and air conditioning. The part is the same for all Blazers of that year regardless of engine size or air conditioning, but this is the normal stream of questions." He goes on to state -- "I don't have a complete part cross reference, but any motor out of a Chevy pickup, GM pickup, Blazer, or Jimmy should work from '71 to '76. The motor may have the part number "1312" on it."

To begin with, my brother had a really nice 72 GMC pickup, for which he just happened to have a spare heater motor. Once I compared my original motor to his spare, I noticed an obvious problem... THEY WERE IDENTICAL!!! So, I don't think you want to use a motor from a 72 GMC pickup.

Then, I went to a local autoparts store (the best in the area, great reputation) and asked to see the heater motor from a 73 Chevy Blazer with 350 and A/C. They brought out what looked to be the correct motor -- although it was 3 1/2 inches in diameter because of some shielding to prevent magnetic interference (all except for my original CJ7 motor had this shielding). I took the motor home and attempted to put it into my heater housing when I noticed I had yet another problem... IT WOULDN'T FIT!!! The mounting flange was set too far back, making it impossible to mount the unit. ARGGHH!!! Now I'm gettin' hot!

Finally, I went back to the autoparts store to try to find a different motor (or maybe even a more shallow fan), only to discover the cause of the problem... the motor must come from a 73 Chevy Blazer (I know this one works, although others would as well) with 350 and ABSOLUTELY NO A/C!!! As it turns out, the mounting flange for the non-A/C unit is properly placed and sits just perfect in the ol' CJ7.

As to your original question, I'm not sure if the 78 motor will work. Compare it's shaft and mounting flange to your YJ's original to see if they match (I assuming you have them on your shop floor, so it's nice and handy). If it fits in your heater housing without any problems and accepts your fan, you should be good to go.

BTW... If you need to enlarge the hole in the firewall to make room for the new motor, use a die-grinder. My brother has a nice pneumatic one, and it carved through my firewall like butta'. Turned out to be the easiest part of the whole project.

Good Luck!

Go easy! You're talkin' to a greenhorn.
 

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My 1980 cj had this really anemic motor,that didn't work. so I went to the parts store to get another one but the one they sold me was toooooo big to fit through the firewall so I took it back.This is before I knew about the upgrade thing.but after reading about the motor upgrade I did order one from a 73 blazer and it did fit my CJ squirrel cageand mounted to the box and worked very well....So the moral is you may not need the upgrade if you have a bigger motor already ....the CJ motor was about 2 1/2 " diameter and the blazer was about 3 " or so.If it is not blowing enough air through it you may need to take it apart and clean out all the dead leaves and rats nests and such.possibly fix the valves that direct the air and put it back together .

Learn to let go of what does not serve you ,but forces you to serve it
 
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Discussion Starter · #5 ·
Hmmm... maybe my trusty-rusty local autoparts store had the wrong part numbers in the 'ol computer -- it figures. However, there's no question the motor that their computer said was for a 73 Blazer with 350 and A/C would not have fit in my CJ (not without a larger heater housing anyway), whereas the motor that was supposedly for the 73 Blazer with 350 and NO A/C fit just fine.

Oh well, the important thing is that now I don't have to drive around with the windows rolled down to defrost/defog -- I rarely even need to set the fan to high.

BTW, rkcrawl... NICE webpage!!

Go easy! You're talkin' to a greenhorn.
 

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I found the same thing here. I tried to do the swap on a 79 CJ using the blazer WITH A/C and found it would not bolt up to the heater box. The mounting flange on the motor was set too far back and the motor would "bottom out" before the flange reached the heater box. Went back and got one WITHOUT A/C and it bolted up just fine. Without A/C worked just fine on the 83 CJ I'm doing now.

 
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Discussion Starter · #7 ·
Anyone know what motor might work in a '76 CJ5? These do not go through the firewall.

My other vehicle is an Aircraft Carrier.
 
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Discussion Starter · #8 ·
thanks guys for the help! i am going to bring the motor to the parts store and see what one is close, but has a bigger diameter housing, i will be asking for a 73 blazer w and w/o a/c and see what ones work and i will let every one know.
Andy

 
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Discussion Starter · #9 ·
The later YJs came with the larger motor, so you may not need to cut your YJ tub, I believe they changed around '91 to the larger motor. Hope this helps, good luck at the parts house!

 
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