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High Mount AC

68K views 93 replies 34 participants last post by  kladd  
#1 ·
I have got some more interest in the f800/ freightliner High Mount AC set ups, and noticed the used prices were still quite high.:eek:

These are current retail prices from Rocky Mountain Cummins...any cummins dealer in your area should be able to get them.

3930888 Water inlet (The big cast piece)------------166.91
3930820 Alt support mount---------------------------29.14
3920862 Alt brace (does not work with dodge outlet)--31.31
3978021 Belt tensioner------------------------------158.35
3921382 Belt tensioner bracket-----------------------42.47
3906697 Rec O ring-----------------------------------3.23


The high mount ac (i guess really a mid mount ac) uses a 95 f800 compressor and 22 si alternator. I used it in a 6bt Chevy to clear the frame rails, but it works great in a lot of different applications. The other advantage on a 4bt is that you can still use the front lower motor mount area.



You will still need a water inlet that matches your set up, also a pretty easy part to fab yourself. I also made a new tensioner bracket, but it would have been very simple to modify the stock part, it is just a chunk of flat 3/8 plate.


The alternator brace won't work with the dodge outlet (not with out trimming a LOT of meat off of it), so I sell a custom bracket that allows you to uses the oulet. You can also change the outlets to a straight up style, which also works well, better in many cases.

 
#4 ·
curious as to the part number of the sanden AC compressor you usd...
 
#5 ·
Got prices on these parts from my local Cummins dealer
in Rocky Hill, CT

3930888 Water inlet (The big cast piece)------------188.61
3921382 Belt tensioner bracket-----------------------77.24
3906697 Rec O ring-----------------------------------3.23

Not sure why the big difference in prices, but still cheaper than some of the used setups out there
 
#7 ·
The 2nd gen dodge one won't work. I don't remember the model compressor it was offhand, but the application I used was a 1995 Ford F800 with a 5.9, and IIRC it was bought from the dealership.

.
 
#12 ·
OK, I'm going this same direction too in a Hummer H3 buildup (build thread coming soon). Picked up the following from Cummins Mid-South yesterday :

3930888 - bracket $158.13
3930820 - lower alt support $27.60
3920862 - upper alt arm $29.66
3930838 - tensioner bracket $40.05

Add $18.05 freight charge and taxes to the above.

Couple of questions :

1) It looks like I have a different tensioner bracket 3930838 vs 3921382. I noticed that the tensioner with this bracket has only about 10 deg of rotation before it contacts the front case. I may have a little bolt slop to shim it forward a tad. Are these two brackets different?

2) I have upper water outlet 3914409 which points straight up which should work well with this combo. No interference.

3) Lower water inlet I have 3903103 which points forward and down. This will interfere and not work. Is the 3916625 inlet which points straight to the passenger side the preferred/common part used in this combo?

4) Can someone confirm the 4474 sanden will work with the horizontal filter arrangement? I have seen conflicting information.

Edit : I just noticed I've been lurking here for 2 years before my first post. I've sponged up so much information from this site its not even funny.
 
#13 ·
The 3930888 bracket will not work with the horizontal filter arrangement. I'll post some pictures here once my post count allows.

For now I'm going with a custom bracket to mount my existing ac compressor up top and the alternator below. The alternator is slimmer than the ac compressor allowing it to squeeze in front of the filter in the traditional location. I'm mocking up an arrangement now which should keep everything below the valve cover height.
 
#19 ·
I couldn't look the belt number up, the truck it was in is currently in pieces with no belt in sight.

Are you running the belt like the f800? crank-tensioner-compressor-alt-water pump- fan? I was worried about the ac compressor wrap also; I considered routing over the waterpump first and moving the tensioner, but I really prefer the tensioner be last in line, and it wasn't that great of an improvement.

.
 
#20 ·
I`ve got the same set-up that`s in your pictures. the belt routing is: crank, A/C compressor, water pump, alternator, fan hub, the tensioner is under the A/C just like the pics. the kit I got came with a cummins belt #3289886. and the belt is a little too long. I dug up a dayco gold label #5080825 and it will just slip over the water pump with the tensioner all the way loostened. the A/C , alt, and water pump all have 180 degree wrap. I`m putting this on my VE pumped `99 24v. I think I`m using a `96 fan hub and damper. that may be why the cummins belt is a tad long.
 
#23 ·
I`m using the `99 stock water neck. everything clears .
 
#25 · (Edited)
I`ll see if I can send a pic that I just took. if you`re using a 12v cummins, you may have to use the straight up thermostat housing like rube stated above, but with this belt routing you`ll not have any belt slippin`. cummins changed the thermostat housing on the 24v engines. that`s why I have no belt clearance problems. check post #20 for the belt number.
 

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#27 ·
3921382 Belt tensioner bracket-----------------------42.47


I'm sorry to be revisiting this thread so sporadically, but I figured I'd get caught up today...




Are we sure the 3921382 part number correct? I bought a water inlet that has this part number on it. It's the water inlet that has a 3-bolt flange, and points downward, a little more than 90 degrees. Both the Cummins sticker and laser etched number on this part say "3921382".
 
#28 ·
3921382 Belt tensioner bracket-----------------------42.47


I'm sorry to be revisiting this thread so sporadically, but I figured I'd get caught up today...




Are we sure the 3921382 part number correct? I bought a water inlet that has this part number on it. It's the water inlet that has a 3-bolt flange, and points downward, a little more than 90 degrees. Both the Cummins sticker and laser etched number on this part say "3921382".

3921382 is the lower water neck with 90* downward turn.

The belt tensioner bracket is. 3930838. I used a stock dodge belt tensioner from orilleys. Line code GAT part number 38517. It was $96.49


Sent from AutoGuide.com App
 
#31 ·
Here are a couple pics of how I did my belt setup. I am using a straight out lower inlet and a straight up upper outlet for the radiator hoses. I built my own mounts and tried to get my motor as low as possible. My lower radiator nipple sits about 1 and a half inches above the frame and my motor is back as far as I could push it to the firewall. My motor/trans is offset toward the passenger side of the frame about 1 inch to help with clearance of the truck air compressor/power steering setup that mine has.
 

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