M939 Series Arctic Personnel Heater Installation Questions

bluehorse

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clackamas, Oregon
I have an M35 Arctic heater kit to install in an M925A2.

Does anyone have the directions for installing a arctic heater kit into an M939 cab?

What modifications are needing to be done to install this kit into an M939 truck cab?

Are any additional parts needed and if so where would I get them?
 

74M35A2

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It replaces the heater core box under hood. Takes 2 unique brackets to do so. I bought these brackets, nobody had them. Had to do the TM and NSN search, then contact the original supplier. I bought a buddy lunch to do all that because he was bored. Sorry lost all that info years ago, but you could easily follow the same path. Also need to change the flexible ducting material in the cab to the orange hi-temp stuff. The flex stainless heater exhaust blows against the engine oil pan lower portion if you are installing it to spec. Here is a pic of one installed in an M939a2 to guide you (not my truck):

923FFHeater.jpg
 
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bluehorse

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Location
clackamas, Oregon
1.) Do you notice if it sucks fumes from the engine bay in much?

2.) Did you have to put a bung in the fuel tank?

3.) Any pictures of the wiring and fuel pump, filter mounting?

4.) Where did you pull electrical power from?

5.) What happens with the old heater blower switch and wiring?

6.) Where do you get the high temp orange duct tubing from?

7.) Is the duct tubing that comes with the kit adequate to use or should it be tossed?

8.) How is the air volume from the new heater blower?

9.) Any value in all the left over parts from this kit?
 
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74M35A2

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Wow. I feel like I’m on a job interview. You’re welcome for the pic, it is not my install. That’s everything except asking me to do it for you. I have not installed it yet, so I can answer some, not all.

1. NA
2. I would install a dedicated tank dip tube and pump, as to not risk the engine sucking air.
3. NA
4. Switched side of PCB.
5. Nothing, it sits there. Change it into a warning beacon or overhead lightbar switch.
6. I steal it from work. You can find it here: https://www.mcmaster.com/flexible-duct or here: http://www.flexicraft.com/Industrial_Hose/FD1/
7. Should be OK, but I would use new vs old.
8. NA
9. No

I plan to relocate my heater core setup to under the pass seat. It can maintain heat but takes forever to warm up a cab from a cold start. Diesel engine does not make much heat until under load. Fuel fired for quick heat, heater core type to maintain. Fuel fired are hot, thermostat is window down position.
 
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WillWagner

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Your ISL will make heat quickly.....IF you ever get it in!
 

bluehorse

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clackamas, Oregon
Thank you for the pictures and information.

I haven't quite figured out how to respond to post on here yet.

This site seems less user friendly than other sites I have been on as far as reponding to post.

I'm used to having a Thank You tab to hit but I dont see one and I'm easily side tracked.

I wasn't meaning all those questions for you but to who ever knew any information and I numbered them so I knew what question anyone was responding to.

I'm working on the project but basically blind since I have no directions and just a few pictures and I don't want to mess anything up.

Thanks again.
 

74M35A2

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You're fine. The heater really just takes the place of the heater core and blower box under hood, requires 2 crescent shaped brackets to do so. It should have more air output that the heater core blower, at least it feels that way when I run my fuel fired heater on a test bench.

Not many people have or use this type of heater, I think maybe a few reasons. A lot of members live where they don't need a heater at all, members park their recreational truck during the winter, and/or these heaters are somewhat picky and not that reliable. I work with a few vets who say in tanks where these were common, they never worked.

I've had decent luck by priming the wick first. Pull the igniter out, pour diesel down the tube, let it soak, then reinstall and try it. Will smoke like crazy due to excessive fuel, but run good during and after that.

The one you are speaking of should be a 30k BTU unit. There is also a 60k BTU one which is much larger, I have that for my cargo bed, again, not installed. Test fire your heater first before you do the work of the install. It is somewhat simple, supply pressurized fuel to it, the hi/lo is just a timed circuit which gives the fuel supply solenoid 2 different pulse rates. You should be able to run the heater on low at any temperature. It should not run on high if testing indoor, as the internal high temp limit switch will shut it down.
 
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Wildchild467

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All the part numbers for this heater are in the manual. I had to dig deep to find them for the mounting brackets. If you were going to save parts from your old heater it would be the blower motor and the heater core.... Or save it all so if you decide to go back to the original setup, you have it. I have a buddy who has a 5 ton that had crappy heat and it was because of a clogged heater core. I replaced it for him and and has happy as a clam with the heater performance.

Also if you take your old system out, make sure you leave the blower motor in the housing when you have it in storage. If the squirrel cage fan gets bent it throws it out of balance and will vibrate. Keep it in the housing for protection.
 

steelsoldiers

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You will love the fuel burning heater. I had one in my 925A2 and 923A2, and it was great not having to wait on the engine to warm up to have heat. It would get so hot in fact that the windshield would be steaming when running it on defrost and I would have to roll the window down because the cab would get so hot. I have one sitting in the garage right now waiting to be installed in a M756A2 Pipeline Truck.

Good luck with your install!
 

74M35A2

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Whoa, a message from the Gods! Excellence. Now it needs to happen.

Noted, thanks. Plan to move the hot water heater to under the pass seat (shorten the core box). Use the fuel fired for initial, and hot water as maintain. Window is thermostat as you mentioned.
 
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