Heater install of M35A3 unit in M35A2

[deucer]

Help with heater unit - brown mud

I bought a used heater unit from an M35a3 with everything to install, or supposed to. I noticed that at the point where the hoses connect to the heater core is a brown mud looking substance as seen in the pictures. It is not plugged off but is a gathering, and the slight amount of coolant that did not drain prior to shipping appears to be brown. I hope I did not get ripped off. I was going to try to flush it but was not sure if that is appropriate and worth the time. If I do and water flows through it am I likely alright?

 

[wb1895]

Just flush it with lots of clean water. The mud is just some sludge that builds up over time in most all cooling systems.

 

[deucer]

Help with heater unit - brown mud

Just flush it with lots of clean water. The mud is just some sludge that builds up over time in most all cooling systems.

Thanks. I did that and it cleaned up real nice after 1/2 hr. with the garden hose.

 

[deucer]

As the title suggests I am performing a heater install of an M35A3 unit in my M35A2. I have looked through every posting I can find (which seems like allot) and unless I am missing it I do not see any posting that directly relates to the install of a M35A3 unit in a M35A2, it was originally inside the cab and I am doing the same. What I am looking for are any potential pitfalls or extra parts I might need. I was told it should fit without any major modification but I am confused because I see all kinds of posts about flipping the units 180 degrees or chopping boxes etc, but I just want a simple install as it was in the A3. I have all the steel parts including brackets and the controls and the duct work and what appears to be short coolant hoses, one with a lever on the end, but they seem too short. I will upload a picture of everything I got when I get back to the house in 5 minutes. The blower motor has a wire coming off it but I don't think I have anywhere to hook it up, but presume it goes to the off-high-low switch which appears to have a resister but no other wires but has space for one more wire to come off. If that spot is for the motor than where in the heck does the main power go then? Thanks in advance.

 

[deucer]

Here is a picture of the unit before it came out of the A3.

 

[deucer]

Pictures 1-4 of 8

 

[deucer]

Pictures 5-8 of 8 initial

 

[gimpyrobb]

Might also want to fill it with some white vinegar, a mild acid, to help clean it out. I'd let it sit over night.

 

[deucer]

In looking at how the valve on the hose works it appears that I may have the ends that go under the hood but not the hoses that hook directly to the core or go through the or to the firewall and they must meet at a juncture or connection at some point. That means the temperature control cable gets routed through the firewall too to connect to the valve? I am still learning so please excuse my ignorance.

 

[deucer]

Alright. Maybe my posting was overwhelming or I am the first to do this which I highly doubt. So my question right now is regarding just the heater core and hose. The core is not marked which one is the inlet. I presume it is the shorter pipe coming of but maybe someone can confirm. Also, what kind of hose are people using, I saw pictures of the blue silicone hose but I did not think that was as strong as the original multi layer hose?

 

[deucer]

Heater hi-off-low switch hookup

I am trying to figure out the wiring so i can install an A3 heater setup in my A2 and it appears I am missing a wire that comes off the back of the switch that goes to the blower motor and another wire that would presumably be the power to the switch (looks like it would typically have an inline breaker or fuse). The problem is all I have is what you see in the picture and the wire hook ups are just numbered 1, 2 and 3. Does anyone have a moment to see how their A3 switch is wired so I can properly hook the switch up. I have the resister hooked to the switch, that is all. I will be feeding power from a solar tech fuse panel so I am thinking I just need to run a power wire to the switch somewhere and one from the switch to the blower motor?

 

[deucer]

Heater hi-off-low switch hookup

Here is a picture from another post that gives me an idea of the two other wires but not how they are hooked up.

 

[m-35tom]

A2 and A3 are wired the same. Power from the heater circuit breaker on the firewall goes to the 'pole' of the switch (probably the center term in most switches that are single pole, double throw, this one is also center off). The resistor goes from one 'throw' to the other, and power to the motor goes to either 'throw' of the switch. One position will flow directly to the motor (hi), the other will go thru the resistor (low).

 

[deucer]

M35A3 heater core

Which is the inlet? Neither is marked. I presume it is the shorter one based on regular cars but did not want to assume if someone knows how theirs is hooked up.

 

[cranetruck]

Yes, the coolant enters at the top of the core (short tube).

 

[deucer]

M35A3 heater core

But that is where I get confused because the tubes come in side-by-side on the bottom and it is the longer one that curves and comes in from the top.

 

[RedbeardTheZombieHunter]

Does it make THAT big of a difference? The water goes through it and warms it up to heat the air passing through. Does it matter which way the water is going?

 

[rtk]

I don't think it makes a difference , I installed mine did not concern myself with the hose placement , works great plenty of heat . BTW , My heater core leak was actually the hoses clamps , some body cranked on them so much , they crushed the heater core tubes . go figure .

 

[deucer]

M35A3 heater core

I thought maybe that w the case but I see several posts of incorrect hook ups resulting in no heat and all they did was swap the hoses under the hood. Plus this article not only shows which hookup points to use but it shows which one is the inlet and which is the outlet under the hood.

 

[deucer]

Heater hose and fittings

I am going to be working on installing an A3 heater in my A2 this weekend, but the problem is the truck is a 2 hour round trip and I am not sure what size fittings I need to fit in the block. I would prefer to have the parts I need with me rather than find out upon arrival and have to run to town. I know the hose is 5/8" but I am not sure what size the fittings are. I am hoping to find the fittings that have a built in valve in case I want to valve the heater off too, if anyone has done that and could provide a potential source. Thanks for all the help to date and in advance.