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 thomas freightliner heater problem
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yellow53
New Member

5 Posts

Posted - 12/17/2009 :  11:14:39 AM  Show Profile  Visit yellow53's Homepage  Reply with Quote
I have a 2006 thomas 44 passenger school bus that blows air like the wind but there is not a bit of heat in the back of the bus. The front is toasty and the defrost works but the kids in the back are not comfortable as there is no heat blowing out just air. I do not think the water is circulating properly. I have checked the heater hot and cold switch, changed that, the motor on the bottom of it rotates so that was not it but the midship heater heats a little but in the back there is no heat at all. The hoses are all good and not crimped but the hose that leaves the front heater goes underneath the floor, is this the only way to check that. I unhooked the back heater and checked the lines and it still does not circulate after the first heater. COuld it be air locked? If so how do you get the air out of the hose, there is a block on the front that has a purge valve from when it was new I opened that and left the cap off the holding tank and drove it hoping it would push air through the hose but it did not if that was even the problem. Iam at my wits end. Supposedly there is an inch hose that goes into the front heater but the heater is cut down to half inch copper and supposedly everything has to go through the front heater before it can reach the middle and back. Has anyone ever heard of the front heater plugging? I can not feel any pressure on the hoses has anyone had this problem and if so what else can I do? Thanks.
Gary

Bassman
Top Member

USA
516 Posts

Posted - 12/17/2009 :  11:26:36 AM  Show Profile  Reply with Quote
This may be completely different....but....our FS65's have an electric valve at the front heater core that is controlled by the center temp control knob which electrically activates it. When this valve fails, we lose our LS and rear heat. Maybe yours is plumbed differently and that valve is bad blocking flow to the rear heater. Otherwise, you probably have a restriction.
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bwest
Administrator

United States
2356 Posts

Posted - 12/17/2009 :  12:14:19 PM  Show Profile  Reply with Quote
My 05 is similar but has a manual valve operated by a cable. I have been know to chase my tail wondering what the problem is when it was that valve not turned on all along.

I also have a tool rigged up to flush with. It would be a good way to check it. What I do is put a ball valve on the end of a garden hose with a nipple on one end. I hose clamp this valve to the heater hose going into the bus then the hose coming out the other side I pull off the fitting and leave open so it will dump out on the ground. Turn on the valve and let er rip.

Good luck

Bryan
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yellow53
New Member

5 Posts

Posted - 12/18/2009 :  04:57:06 AM  Show Profile  Visit yellow53's Homepage  Reply with Quote
Thanks for the suggestions. I will do the flush today and see if that helps. If not what then??? Anyone else have any ideas?
Gary
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Brad Barker
Administrator

USA
838 Posts

Posted - 12/18/2009 :  3:04:10 PM  Show Profile  Visit Brad Barker's Homepage  Click to see Brad Barker's MSN Messenger address  Reply with Quote
Does Thomas use a heat pump? Heat goes to the front first to insure the defroster will work for safety purposes. Sounds to me like you do not have enough circulation.

Brad A. Barker
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baptistbusman1
Senior Member

USA
76 Posts

Posted - 12/18/2009 :  4:10:32 PM  Show Profile  Reply with Quote
without a doubt your front controller is broken. You have to take the drivers seat loose from it's base. Then remove the panel under the all the heater switches. The controller is facing backwards under the front heater motor. You will have to take the heater core loose.

Trust me on this, I just worked on 2 of these in the last two weeks. Don't bother with flushing the system.

I was formally Baptistbusman. However, I lost my password, and had not updated my email address.

Here is a link to my old posts. http://www.schoolbusfleet.com/forum/search.asp?mode=DoIt&MEMBER_ID=1846
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Cal Mc
Advanced Member

256 Posts

Posted - 12/18/2009 :  8:25:46 PM  Show Profile  Visit Cal Mc's Homepage  Reply with Quote
I am not sure about your unit but the Thomas buses use a parallel connected heaters rather than the series connected Bluebird heaters. The heaters use a restrictor to stop excess flow through the heater which if not in place will short the rear heaters of flow.
Check your heater valve first. Then check for a lost restrictor.
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JustinB
Advanced Member

United States
490 Posts

Posted - 12/21/2009 :  05:22:21 AM  Show Profile  Reply with Quote
We've had a lot of fleets in W MI reroute their Thomas buses fom a parallel system to an in-series system.

I may not know the answer but I can usually find who does.
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yellow53
New Member

5 Posts

Posted - 12/21/2009 :  09:18:26 AM  Show Profile  Visit yellow53's Homepage  Reply with Quote
quote:
Originally posted by baptistbusman1

without a doubt your front controller is broken. You have to take the drivers seat loose from it's base. Then remove the panel under the all the heater switches. The controller is facing backwards under the front heater motor. You will have to take the heater core loose.

Trust me on this, I just worked on 2 of these in the last two weeks. Don't bother with flushing the system.

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yellow53
New Member

5 Posts

Posted - 12/21/2009 :  09:24:30 AM  Show Profile  Visit yellow53's Homepage  Reply with Quote
Thanks for all the help. I did flush, and it was a waste of time but I did not get to read the rest of the posts until this AM. I came to work yesterday and sure enough it was the front controller. I did not have to take out the seat though. I took off the panel then unhooked the two rubber hoses and then you can pull out the heater far enough to take off the electric motor that turns the valve, then I took it the rest of the way out. I ordered a new valve but it has heat until that comes in. After you figure out what the problem is,it only takes about 45 minutes, but it took me hours to get to that point. We will have this 56.00 part on hand from now on for spares. Thanks.
Gary
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Bassman
Top Member

USA
516 Posts

Posted - 12/21/2009 :  1:12:42 PM  Show Profile  Reply with Quote
Definitely put it in stock. We started stocking them and have used 9 or 10 and we only have 31 of these buses from 2003 - 2007. I had just put one on a bus the day you posted your original question.
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