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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.

 
#63 ·
The mounting feet have a different spacing top to bottom. You can't turn the compressor 180* and mount it. The manifold on the back can be unbolted and turned but at this stage I want to know how they are going to fix this before I go opening up the compressor. I am still left after all that with what looks like a poorly rebuilt compressor with a 5 rib clutch.
 
#74 ·
Don't know if there's much frame difference but here's some photos of the high mount system in place in an '87 blazer. You'll note this engine has the vertical oil filter. Don't know if there's any issue with the horizontal one common on most 4bts. Back of the ac compressor and oil filter are close as you can see. Also, here's a photo of the complete assembly on an engine. This one has the Ford inlet pipe.
 

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#75 ·
Here's some photos of the same setup in a C20. I also have some dimensions in there for the AC hoses to match up to an 85 condenser.

 
#76 ·
I was lucky to find a 1st gen CAC equipped 6BT fan pulley and mounted it to a 3rd gen bracket to get the clearance needed.
 
#77 ·
Subrutus, that is interesting. Those shorter pulleys use different mounts so the belt alignment is correct. Only the '91.5-93 engines used it. Here's what the 2 pulley designs look like. Didn't realize that pulley would fit the 3rd gen mount. Learned something new. I have one of each of those mounts and never thought about the early pulley might fit the later mount.
 

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#80 ·
Grendel, are you talking about the high mount AC parts? If you have a 4bt, those parts will mount to it. They never came on a 4bt but were on tons of 6bt's in trucks and buses. One area you have to be aware of is the engine mounts. The bottom bolts in that AC mount occupy the holes often used for the engine mounts on a 4bt. There can be other minor issues depending on what vehicle you plan to put it in. Biggest issue is often the cost. Tennessee Diesel Conversions sells the complete setup excluding the bolts for $1425. See photo below. Might seem expensive, which it is, but those parts are all Cummins except the compressor and alternator. If you could get the parts off an engine in a salvage yard you may save quite a bit. There are also AC brackets that put the compressor on the driver's side of the vehicle. Those were often found on Case backhoes. The AC compressor on those runs off a separate V belt instead of the 8 groove. Not a cheap setup either but less than the other one.
 

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#81 ·
Grendel, are you talking about the high mount AC parts? If you have a 4bt, those parts will mount to it. They never came on a 4bt but were on tons of 6bt's in trucks and buses. One area you have to be aware of is the engine mounts. The bottom bolts in that AC mount occupy the holes often used for the engine mounts on a 4bt. There can be other minor issues depending on what vehicle you plan to put it in. Biggest issue is often the cost. Tennessee Diesel Conversions sells the complete setup excluding the bolts for $1425. See photo below. Might seem expensive, which it is, but those parts are all Cummins except the compressor and alternator. If you could get the parts off an engine in a salvage yard you may save quite a bit. There are also AC brackets that put the compressor on the driver's side of the vehicle. Those were often found on Case backhoes. The AC compressor on those runs off a separate V belt instead of the 8 groove. Not a cheap setup either but less than the other one.
 
#84 · (Edited)
Rob's list is just the main parts of that puzzle. Which water inlet are you using. I have the complete list of all the bolts, roll pins, O rings, etc if you need them. Here's the list.

3930822 Main AC mount
131584 Roll pins (2 req) Aligns unit to block.
3008468 1/2" NPT plug
3008469 3/4" NPT plug (may not be needed depending on you coolant plumbing)
3900630 M8x1.25x20 Flange Head bolt (2 req) Attaches Small L brace
3900679 M10x1.5x80 Flange Head bolt (3 req) Attaches Lower Water Inlet
3906697 O Ring (2 req) One between mount and block and other seals lower water inlet.
3910495 M12x1.75x30 Flange Head bolt (3 req) The length of these would change with engine mounts.
3921382 Lower Water Inlet (this one points straight down)
3941929 Optional Lower Water Inlet (this one points straight out to the side)
3920862 Upper Alternator Mounting Arm
3930820 Lower Alternator Mount
3052061 1/2x13x1 Bolt (Attaches alternator to upper arm) Probably only non metric bolt on the engine.
3903105 M12x1.75x150 Flange Head bolt (Attaches alternator to lower mount)
3903210 M12x1.75 Flange Head Nut (For above bolt)
3900621 M8x1.25x25 Flange Head Bolt (2 req) Attaches upper alternator mount arm to head.
3900623 M10x1.5x25 Flange Head Bolt Attaches lower alternator mount to main bracket.
3922606 M10x1.5x45 Flange Head Bolt Attaches lower alternator mount to main bracket.
3924068 Small L Brace
3930838 Tensioner Mounting Plate
3978021 Tensioner
3900631 M8x1.25x25 Flange Head bolt. Attaches tensioner mounting plate to main bracket.
3904446 M10x1.5x70 Flange Head bolt. Attaches tensioner to mounting plate.
3285102 Upper Water Outlet (This one points straight up)
3923331 Water Outlet Seal
3926972 M8x1.25x70 Flange Head bolt (2 req) Upper water outlet to head.
3900632 M8x1.25x35 Flange Head bolt Upper water outlet to head.

Below are the parts diagrams for the 2 sections of that setup. The first is the main ac bracket and the second is the alternator parts.
 

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#86 ·
I would like to ask again a question about A/C fittings for the Ford/Sterling 7h15 compressor. There are pictures of it all over this thread.

This compressor has a "WH" head with the fittings clocked at about 2 o'clock. What are they? Threads are too fine to be universal o-ring or insert o-ring. I found these "WH" fittings described as "Ford o-tube pad" by a compressor vendor. But I can't match that description with anything from the online AC vendors. What am I missing?

thanks
kevin
 
#87 · (Edited)
The compressor you reference had several applications. It came on the '99-08 Sterling and also on earlier Ford F800 trucks equipped with the Cummins 5.9. That one is an SE7H15. See photo below. Also came on Freightliner trucks. I do not find a WH head in the Sanden catalog. The only 2 in that 51 deg angle are the WN and WY. Both have the same ports which are M8XP1.25 bolts and a pad (UG) type . For some reason that doesn't seem to match the photo I have because there are no bolt holes in that area. Did a bit more research and there is a WH head. Trying to read a Sanden catalog is like trying to decipher Greek. This is sort of a guess but I believe the ports are 3/4-16UNF and 7/8-14UNF. Appears to require a #0013 and #0015 O ring. An ac shop could tell you for certain.
 

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#88 ·
I bought the compressor as part of a kit from Scott (crewcab59) about 8 years ago. A standard male #8
Image
Image
o-ring fitting which I think is 3/4-16 screws into the discharge port about a turn and a half - the threads on the compressor are just a bit more fine.

What Sanden rear head is everyone else using? If I have an oddball head then maybe I can just it switch out. The 2 o'clock position for outlets is perfect.

yeah taking the compressor off the truck and to an AC shop is starting to make sense, even here in rural Maine.

thanks for all help,
kevin