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Grant Thiessen (Busshawg)
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Username: Busshawg

Post Number: 61
Registered: 10-2007
Posted From: 206.45.93.160


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Posted on Monday, November 17, 2008 - 11:09 am:   

Here I am again looking for help. My 1984 MC9 isn't producing any heat to the passenger part of the bus. It blows nice and hot up through the drivers side. I realise there are 2 different control valves to reg. the 2 sources. However my question is has anyone removed the heat control valve located in the front cargo compartment and replaced it with a manual valve or maybe even just installed a line without a valve at all? As there is valves in the motor compartment. My valve doesn't appear to be working properly as the lines are hot on one side and cool on the other. Thanks for all your input.

Have fun!
Buswarrior (Buswarrior)
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Username: Buswarrior

Post Number: 1386
Registered: 12-2000
Posted From: 76.69.141.137


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Posted on Monday, November 17, 2008 - 11:38 am:   

Check the electrical to the valve. Power on closes the valve, power off opens.

The thermostat circuits may be your culprit, not the valve itself. The temp sensor in the return air duct is target number one, the rheostat on the side dash is target number two, and broken wires of course...

Got power? Pull the wire off the valve and see if you get flow.

There are two valves in the engine room. Return and supply. Return is inside curb side side access down near the frame rail, the supply is in the pipes on top of the motor above the transmission, as the lines head toward the tunnel forward. Regular gate valves, turn the handles round and round in the normal fashion.

If the pipes are warm, and you've got driver heat, the valves are already open to some degree.

happy coaching!
buswarrior
Mark Renner (Boomer)
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Username: Boomer

Post Number: 121
Registered: 11-2006
Posted From: 70.192.112.161


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Posted on Monday, November 17, 2008 - 11:55 am:   

As Buswarrior says, first check the solinoid in the front bay for proper operation by testing the continuity when you turn your reostat to full heat. If that checks out, open the small inspection cover in the air return tunnel and find the thermbulb (thermostat). They commonly fail. New ones can be obtained from MCI Parts.
Grant Thiessen (Busshawg)
Registered Member
Username: Busshawg

Post Number: 62
Registered: 10-2007
Posted From: 206.45.93.160


Rating: N/A
Votes: 0 (Vote!)

Posted on Monday, November 17, 2008 - 12:08 pm:   

Thanks guys, I have not been able to get power to the vavle. With the wire on or off. I can not get enough flow to heat up the core either. I did take the valve off and tried to blow through it . I can blow through but it seems quite restricted. Does this mean it may be the temp sensor? Either way can a person eliminate this valve? I realise that I would not be able to control the volume of hot coolant circulating though the heater core from the driver seat, however it may get me up and going while I am waiting for parts. By doing this I should have a hot heater core , right?

Have Fun
Thanks
Jack Conrad (Jackconrad)
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Username: Jackconrad

Post Number: 874
Registered: 12-2000
Posted From: 71.54.29.215


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Posted on Monday, November 17, 2008 - 1:20 pm:   

We removed that valve on our MC-8, dis-assembled the valve and gutted it. We then re-assembled it and re-installed it. Our heat control was opening or closing the valves in the engine compartment. Jack

PS: Since our travels are always in the SE or warm weather, we have since removed the passenger heater core and rely solely on the driver's/dash heater core for warmth when traveling.
Buswarrior (Buswarrior)
Registered Member
Username: Buswarrior

Post Number: 1390
Registered: 12-2000
Posted From: 76.69.141.206


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Posted on Tuesday, November 18, 2008 - 11:44 am:   

Hello Grant.

Try running a hot wire directly to the valve and see if you can spark it into moving.

Otherwise, as Jack did, get it returned to functionality

You really want an automatic control, that heater core is a monster and will boil you out. Regulating it by manual methods will give you wildly fluctuating temps inside the coach going down the road, and require you to be involving yourself every few minutes in its control.

Do you have the picture of the valve from the maintenance manual? It has quite a number of parts inside.

happy coaching!
buswarrior
Grant Thiessen (Busshawg)
Registered Member
Username: Busshawg

Post Number: 63
Registered: 10-2007
Posted From: 206.45.93.160


Rating: N/A
Votes: 0 (Vote!)

Posted on Tuesday, November 18, 2008 - 1:32 pm:   

Thank Busswarrior. I really apprieciate your imput, I can tell you know what your talking about and value that very much. I understand what your saying and will try to get this going. It's not that I have to have right now and not sure how anxious I am to work on it as it is getting quite cold here in Manitoba and I can't get it in my shop. Either way now that I understand better I can work on the vavle in my shop and take from there. I guess if there is a power problem I could always install a new wire from the thermostat control from the drivers control. This conversion project is quite the challenge , which I enjoy but could not get through it without guys like yourself.

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