Our 4106 still has all the factory OTR heating system in place. This morning there was a nip in the air so I thought I'd give it a go and see if things work.
Well, sort of...
I know that there is hot water circulating all the way to the front since the defrost system puts out nice warm air. However, even with the temp dial (to the left of driver) all the way to 'warm' there was only vaguely warm-ish air coming from the vents.
My guess is that somehow the water modulating valve, the stat, or something else is not fully opening the water flow to the heater core.
I've got the manual and it seems to give quite a few options.
Anyone have a good place to start looking for what may be causing the heat not to flow?
Thanks
Richard
Do you still have the booster motor and pump in place.??>>>Dan
Affirmative. Still have the entire system in place. In fact, we had to use the booster pump to get an airlock out of the system when we reinstalled the generator last week.
Have both the OTR heat and a/c. Glad that they were not messed up by anyone.
Richard
Maybe it's a Wisconsin thing??>>>D
There should be a bleed valve at top of heater core, like the defroster has. I'd start there first. When working properly, it will roast you out. If there is no air in core, use a ir heat gun to compare inlet and outlet temps at core.
Heat? Wisconsin thing?
Sure is - heating season here runs about 2/3 of the year some years. I don't think the high today made it to 70. Of course, that's unusual even for us this time of year.
Quote from: Utahclaimjumper on August 24, 2017, 05:41:21 PM
Maybe it's a Wisconsin thing??>>>D
for sure! Nip in the air in August?
I removed the throttling valve and just installed a manual ball valve. I control heat by just kicking on or off the fans (2-14" 12v radiator fans). Without the throttling valve, I can get plenty of heat without the booster pump. Good Luck, TomC
My MC8 has no booster pump and as Tom said, will drive you out of the rig if on full. My modulating valve is (pretty sure) a normally-open valve so you can easily check it by disconnecting the wires to the solenoid and then it should be on full.
I assume both gate valves are fully open back at the engine
How cold?
Idling makes little heat, but it isn't that cold yet...
No heat if you take it for a drive?
happy coaching!
buswarrior
Quote from: buswarrior on August 28, 2017, 10:34:51 PM
How cold?
Idling makes little heat, but it isn't that cold yet...
No heat if you take it for a drive?
happy coaching!
buswarrior
I had just driven about 40 miles. The defroster was putting out nice warm air, so I know that the system was warmed up and that coolant was reaching the front of the coach.
The air temp was in the low 50s, certainly cool enough to want to run the heat for a few minutes to take the chill off. I turned the knob on the panel to the left of the driver all the way to warm, but it did not appear to have an effect on the air temp coming from the vents.
I'll start going through the list now that I've got a few days set aside to work on it.
Richard
Mine was Doing this too, then I found a valve operated by a cable that opened or closed the coolant line at the front of the coach. I manually opened it and now even when it's in the teens outside, it roasts us out of the coach
Sent from my iPhone using Tapatalk Pro
There will be a wiring issue to the regulating valve in the big pipe leading from the big heat exchanger.
GM experts, where's the valve?
The older MCI, it is up high in the front baggage bay, curb side, front wall corner beside the utility channel, behind a bent cover.
Test it with a power wire, confirm it actually operates open and closed, then go after the electrical gremlin that is obstructing. If the valve won't operate, there you go!
happy coaching!
buswarrior
The 4106 has a pull cable next to the accelerator pedal, but my manual shows it controls the temp of the defrost and heat to the driver's feet. Doesn't appear to control anything other than the heater core at the very front of the bus.
The main heater core for the OTR heat is controlled by the valve in the bay just behind the right front wheel. I'll have to run through the troubleshooting list and see if I can get the valve to open. After reading the manual a few times, it seems that if I disconnect one wire the valve should open all the way and allow heat to flow at full flow. of course, I have no idea which of the many wires the manual is talking about. They all look to be about the same shade of gray at this point. Unless someone has a suggestion I'll just start pulling one by one till something happens.
Richard
My buses were like this ^
Sent from my iPhone using Tapatalk Pro
Go to the valve, not the switches.
On the MCI, it was one wire attached to the valve. Lots more wires further up stream for the temp sensor, blah blah blah.
Go to the device, it usually is simpler.
happy coaching!
buswarrior
Here's the water valve. There are four wires got to it. Anyone know which is 'the' wire that the manual says I should disconnect in order to get the valve to open? (https://uploads.tapatalk-cdn.com/20170830/a844f2ed95c261aeaef04538efd378a5.jpg)
1964 PD4106-2412
Here's a view of the other side of the valve in case anyone wants to see. (https://uploads.tapatalk-cdn.com/20170830/7c48060b07a89257bd7eaffdb25e4905.jpg)
1964 PD4106-2412
take 'em all off? each one, one at a time? Don't let them touch anything or each other.
The pipe will get hot right away, if it opens, if coach is warmed up, and running.
GM experts, is that also a copper airline?
If so, is it getting its air supply?
Some stuff I wished I paid more attention to, long ago and far away...
happy coaching!
buswarrior
I'm with BW, remove the lines one at a time until you get flow. If you don't get flow after this, at some point I'd remove the valve.
Sent from my iPhone using Tapatalk Pro
This might show my beginner's lack of knowledge, but maybe I'm looking for heat when the bus thinks it know better...
When I first start the bus on a cool morning, the 'heat' tell tale lights for a few minutes. According to the manual, this is telling me that the system thinks the passengers will be chilly if I don't turn the heat on. If I'm correct, that would me turning the knob next to the driver's seat to 'warmer' and then letting the system run.
My understanding is that the point at which this tell tale lights up is determined by the setting on the grad-u-stat (located in the floor vent, passenger side).
So, unless the tell tale light on the dash is on, no amount of trouble shooting on my part is going to get the heat to blow warm.
Anyone able to confirm that I've got that right?
Richard