Good evening fellow bus-folk!
My coach bus heat is non-functional. Used to be that it worked so well that I had to make sure not to bake the passengers. Now, not so much. Just blows cold air.
What I've tried: both heater valves are 'open' in the engine compartment to allow the coolant to flow. Valve under driver seat on wall is also in the open position. Opened nut on the heater core by the driver seat - coolant immediately flows out. Put hands on hoses & pipe up front by outside panel - same location of the driver heater valve - the hoses & pipes are all cold to the touch even after running the bus for a period of time to where the temp gauges show the bus is warm.
Would greatly appreciate suggestions! Thanks all, Phil (Cold in the AZ mountains).
Has your coolant electric pump tripped its breaker or blown its fuse? if so, why? Does it share its circuit with something else - if it does, is that other thing also dead?
John
Good morning. I don't have my book in front of me, but I know there's also an electrically-operated valve located in the first bay on the curb side. Mine is located in the front of the bay up near the ceiling of the bay behind a little removable cover. At first glance it would appear to be part of the channel that runs the length of the bus, but it's a little hump with a removable cover. Hope this helps.
Hi all, on initial checkout yesterday we did not find any tripped breakers or blown fuses. However, will give that another shot. Did find about a foot long cover that we removed but didn't see a valve, so it must have been the wrong cover. It was adjacent to the channel that runs the length of the bus. Will get out to the bus a little later today.
Thank you very much for the responses!!
Kind Regards, Phil
There is going to be an electrical on/off valve somewhere that is controlled by the thermostat (temp sensor is usually in a passenger side return air floor duct) and the temp control dial up beside the driver. It simply causes the valve to be fully open or fully closed in response to the temp sensor and a comparator circuit that I never managed to figure out. My 1980 MC-5C has it located in the rear engine compartment (passenger side, low down, right beside the manual shut-off valve) in the main coolant return line from the heater coil in the middle of the bus. There is no electric coolant pump in this generation MCI. When the factory AC is on, the AC runs at max all the time and the temperature is controlled by the OTR heater adding heat to the cooled air.
Ha! Who knew I had this- exactly as you all suspected - first bay, curb side. More testing to see if it's getting power. I see 24volts is listed.
Kind Regards, Phil
If I'm not mistaken, that valve fails in the open position. That probably means that it's being held shut by the control circuit. Assuming you've played with the temp knob on the left, you may need
to check the relay circuit in the driver's side electrical panel. May be a relay in there, too. I can't recall right off.
Are you sure your gate valves are open and not broken. Does the center pipe heat up past the valve?
Thanks Craig, it sounds like the idea is to run the bus 'till it heats up, then check the heat in the coolant pipes to/from the engine on both sides of the valve to determine whether the pipes are warm on both sides, or whether the temperature abruptly changes past the valves indicating they are closed?
Best Regards, Phil
Good morning, and a frosty one it is here in SE Ohio.
Had a similar problem in my '86 Prevost. No heat in lines from engine room. One of the gate valves seemed like it took many turns and didn't really feel like it was opening. Drained, dismantled, could see no problem. Re-assembled.
At the same time, I took apart the solenoid valve up front and found the diaphragm rotted. When I rebuilt it found plunger stuck in the closed position within what Asco calls the "plug nut"; the core upon which the coil mounts. That held what was left of the diaphragm in the closed position. Got heat now!
BTW: I tried going directly to Asco for the valve, no kit available, nearly $300 with 3-4 week delivery. Kit was $150 or so from Prevost, 2 days.
Further BTW: This valve's components are rated for ethylene glycol service. If you're thinking of improvising some other valve, (I'm an improviser, sometimes) it may not last.
Now, how do I get rid of 20 gallons of used anti-freeze?
Quote from: TedCalvert on November 21, 2015, 02:16:54 AM
Good morning, and a frosty one it is here in SE Ohio.
Had a similar problem in my '86 Prevost. No heat in lines from engine room. One of the gate valves seemed like it took many turns and didn't really feel like it was opening. Drained, dismantled, could see no problem. Re-assembled.
At the same time, I took apart the solenoid valve up front and found the diaphragm rotted. When I rebuilt it found plunger stuck in the closed position within what Asco calls the "plug nut"; the core upon which the coil mounts. That held what was left of the diaphragm in the closed position. Got heat now!
BTW: I tried going directly to Asco for the valve, no kit available, nearly $300 with 3-4 week delivery. Kit was $150 or so from Prevost, 2 days.
Further BTW: This valve's components are rated for ethylene glycol service. If you're thinking of improvising some other valve, (I'm an improviser, sometimes) it may not last.
Now, how do I get rid of 20 gallons of used anti-freeze?
Gary Throneberry ("Garhawk") had a similar problem with a solenoid-controlled valve in his coach in central Tennessee. I am pretty sure that we found that it was a wiring problem and not an internal failure, though. But it was same symptoms. On his coach, the valve that was giving problems is up in the very upper right rear corner -- the failure stopped warm water going to all the interior heat and defrost. It was a pretty frustrating problem but easy to trace down and fix. And, yeah, the fact that a hose that should have been warm was cold right after that valve was a big tip-off.
Ted :Our landfill's in N C accept used antifreeze.Might be a good place to start.
Good afternoon bus folks,
I just ran the bus for a while. The attached picture shows the temp on the pipes to answer Craig's question.
For the wiring, to the valve in the front bay along the main chase, when I test, I'm looking for 24 volts, or?
Also attached a picture of the relay, but not sure what to do with that. Relay is labeled "Coach Heat Relay" on the diagram. This is in the front driver side panel, outside.
Thanks all very much!! Kind Regards, Phil
Phil: I have one of those valves left over from my mci days. yours if you decide that is problem. Make sure it is getting power first. Mine was in same compartment the ac and Main heater core was in close to ceiling. bob
Woo Hoo! OK. Thank you Bob. That's where ours is too. Will definitely let you know once investigations are completed. ;D
BigRed: Thanks for the suggestion; I'll look into that.
Pylons: My solenoid valve (Prevost) is normally-open, so if the controller is calling for heat, there should be no voltage on the solenoid valve's coil. Heat set point satisfied=voltage on coil=closed valve. Mine had a plug that I unplugged for testing. That's assuming it's a solenoid valve: either fully open or fully closed. I think my old 4104 had a variable valve originally, according to da book, IIRC. That would be a different animal. Also, if it's an ASCO valve, you can most likely pull the coil off to check the action of the valve. But a word of caution with that trick in other places: don't EVER pull an AC coil off of its core; it will draw lots of current and let the smoke out!
The relay might be to switch the larger current required by the pump motor. One really needs the diagrams, both electrical and cooling system, to figure out these problems.
HTH
Thanks very much Ted.
IF I'm testing correctly, I have _no_ current when bus is off, powered on w/Low air, powered on and fully aired up, and when I turn on the bus heat switch for the coach. I haven't tested when the engine is fully warmed up though.
My point of test is the ground terminal (neg) near the main water valve, and the terminal on the side of the valve (pos).
Does my testing methodology seem correct? My tester only has 10v DC and 50v DC. I tried both settings trying to get any movement out of the needle, but nada.
Kind Regards, Phil
Sorry I didn't get back sooner.
I take it that your meter is an analog meter that has two voltage ranges: 0-10 and 0-50. If that's the case, leave it on the 50-volt range for testing voltage. Make sure that it's set for DC, not AC. Verify that it works by putting it directly on the battery. Nothing is worse than chasing a problem on wrong readings.
Furthermore, I understand that your solenoid valve only has one terminal, and that the other end of the coil is somehow internally connected to the body of the valve and therefore, hopefully, completing the circuit back to the battery through the vehicle's body/frame (ground).
If all that's correct, then yes, you're on the right track to determine if the coil is powered or not. But we don't know if the coil should be powered, or not, when calling for heat.
Maybe you should think about possibly rigging a bypass line around the valve for testing? That's a PITA. Are you sure the system is not air-blocked? My Prevost has a bleed valve off the top of the driver's core. Depends on how the coach is sitting, too.
Good luck; keep us posted.
Thanks for the response Ted. I'll read it a few times to make sure I copy all that you are saying. I'll test out my analog meter on the battery. Great idea. Also, am pretty sure we're not air blocked. I did open the valve on the driver's heater core. Also had a diesel mechanic friend of mine do the same - each time we did that, as soon as the valve was opened, coolant came immediately out. Coach is setting on a level, concrete slab.
Also, I'm going to test to determine whether I've lost my ground, and I'll post back here.
Kind Regards, Phil
Phil, the valve operates with 10v min to 15v max so don't going looking for 24v,the diaphragm is probably bad those are supposed to be replaced every year according to the MCI maintenance program
Hi Ted,
My analog meter seems to test OK when testing against the battery, it shows a little under 28v - approx.
Testing the negative terminal/connector on the suspect valve to the bus ground looks like the ground connection is strong.
Hi Clifford,
Testing positive connector @ 10vdc on my tester still shows no current whatsover at the valve. Clifford, do you know whether these fail open, or closed? I'm ordering the diaphragm through Luke right now.
My valve markings:
Valve - sol.opr.
P.N. 36830062
25PSI - 24VDC
Thanks all very much! Phil
Quote from: luvrbus on November 25, 2015, 01:54:16 AM
Phil, the valve operates with 10v min to 15v max so don't going looking for 24v,the diaphragm is probably bad those are supposed to be replaced every year according to the MCI maintenance program
MC9 is 24v. Only 12v relay in them is the blower relay in the rear panel. Valve is 24v.
I'm suspicious of the gate valve in the rear. The stem on one of mine broke and I had to replace the valve.
I'm also suspicious of the relay. You should swap it with one from that toad converter you bought just to make sure it's not the relay.
There's also a sensing unit in the air tunnel, front bay, left side, by the A/C junction box. That's what sends the signal to the relay.
If changing the relay doesn't do anything, test for voltage on the coil terminals and on the output terminals. You could jumper the coil terminals with
some alligator clips to see if you get heat. If you do, it may be the bulb sensor in the tunnel.
By the way, the photo you posted of the valve is the return valve. The supply valve is up in the center above the transmission.
I think you will find NJT MCI 9's are 10 to 15v on that valve I could be wrong but I have chased that problem on the NJT 9's before
Quote from: luvrbus on November 28, 2015, 11:20:23 AM
I think you will find NJT MCI 9's are 10 to 15v on that valve I could be wrong but I have chased that problem on the NJT 9's before
That would be surprising, but maybe they did something different there just for NJT.
Normal MC9 schematic has 24v going through the 12v discharge and blower cut-in relay to rear stud 2 to feed front stud 30 and then terminals 1, 8, and 7 on the
coach heat relay. From terminal 1, it goes out through terminal 3 when relay is activated to front terminal 43 to AC j-box stud 7, and then to water valve.
The heat relay is activated by the mercury switch sensing unit in the tunnel closing and grounding the coil on the relay at terminal 2.
The schematic says the water valve is normally open.
A lot of things on NJT MCI's are different,I ran across 1 with a DDEC 1 engine that was straight 12 v with a air starter they did that because the DDEC 1 is 12 V only they have their own manuals and it changes with serial numbers, of the 1100 or so NJT Mci 9's you don't see many for some reason
NJT did some weird stuff like the Eagle was a 12V system they used a 24v air and heating system with a air starter then every wire was white in color with a tag you couldn't read.Gary Hatt the owner of this board has a NJT MCI 9 moose cabin also
As suggested, the NJT buses were odd ducks. We owned quite a few MC-9's and as I recall any HVAC problems dealt with A/C, not heat. If both water valves in the engine compartment are open you should have hot water to the cores. Not to say there is not some kind of restriction in the pipes, or perhaps a total failure of the electric water valve but we never saw it happen. The thermo bulb reads the temp of the return air in the tunnel and depending on how the temp reostat is set will open and close the water valve by grounding it. You don't need a volt tester on that valve, it's either working or not and can test with a probe. I would check your gate valves or maybe put a kit in the electric water valve, I don't think the problem is electrical unless it's a NJT thing. JMO
Greeting!
Thanks very much to all for the suggestions. I'm working on this as time away from my day job permits.
I'll swap relays with that from toad converter sometime in the next week or so - great idea. Thanks Craig.
Re: photo, I did check heat around the supply gate valve as well but didn't snap a picture of it. Pipes around supply gate were also hot for a couple feet around both sides of the the valve going up & down the pipe. I didn't check past a couple of feet going forward as I couldn't easily reach the pipe. If it's a recommended troubleshooting step to go past a couple of feet towards the front of the bus along the supply coolant pipe, I'll figure out a way to do so.
Diaphragm rebuild rubber arrived from Luke @ US Coach. I need to figure out how replace that w/o a huge mess.
Is there any kind of pump to move the coolant around the heater cores & pipes that I need to be concerned with, or is all the coolant for the heating system moved by the engine system itself? I don't show any extra pumps in my manuals from 1989, but checking to be sure.
Kind Regards, Phil
Quote from: plyonsMC9 on November 29, 2015, 09:40:19 AM
Greeting!
Thanks very much to all for the suggestions. I'm working on this as time away from my day job permits.
I'll swap relays with that from toad converter sometime in the next week or so - great idea. Thanks Craig.
Re: photo, I did check heat around the supply gate valve as well but didn't snap a picture of it. Pipes around supply gate were also hot for a couple feet around both sides of the the valve going up & down the pipe. I didn't check past a couple of feet going forward as I couldn't easily reach the pipe. If it's a recommended troubleshooting step to go past a couple of feet towards the front of the bus along the supply coolant pipe, I'll figure out a way to do so.
Diaphragm rebuild rubber arrived from Luke @ US Coach. I need to figure out how replace that w/o a huge mess.
Is there any kind of pump to move the coolant around the heater cores & pipes that I need to be concerned with, or is all the coolant for the heating system moved by the engine system itself? I don't show any extra pumps in my manuals from 1989, but checking to be sure.
Kind Regards, Phil
On a normal MC9, there are no auxiliary pumps to move the coolant. All coolant pumping is done by the engine water pump. Evidently you can't count on the normal with an NJT.
Opening the valve shouldn't be a huge mess, but you need to shut off the 2 valves in the rear or it will become a mess when it drains the radiators. Shut those valves, and
also shut the driver's heat valve by the electrical panel. Then you should be able to break the line with minimal coolant loss (1-2 gallons from the lines in the tunnel).
The valve is above the heater core, so not much concern about that. Use a bucket to catch what comes out.
Arrrgh. OK, that makes sense, thanks Craig. But it does look like before I work on the valve I'll need to first fix the rear supply valve which is stuck in the open position. Don't know when I've had more fun... :P
Will swap out relays next week.
Kind Regards, Phil
Quote from: plyons on December 01, 2015, 08:03:01 AM
Arrrgh. OK, that makes sense, thanks Craig. But it does look like before I work on the valve I'll need to first fix the rear supply valve which is stuck in the open position. Don't know when I've had more fun... :P
Will swap out relays next week.
Kind Regards, Phil
Oh, wait. Your supply valve is stuck in the open position? How do you know that?
You may well have just found your missing heat problem. It's possible the gate is closed and the shaft is broken.
If you think it's just stuck, run the bus and heat it up. Then try the valve. The heat may unstick it.
That valve is a real pain to replace. It's soldered in place. I had to pretty much lay on my belly on the floor and solder the new one in using the upside down braille
sweat solder technique. You'll need to drain down the entire coolant system to replace it.
Hi Craig,
Here's how I _think_ I know it's stuck open. As long as I've owned the bus (over 10 years now) - that valve has been stuck. Back to when the heat used to work amazingly well. During summer I would just close off the driver side valve and the return valve.
I don't think I've tried to turn the supply valve with the bus heat up tho'. Pretty sure I always turn the vales with the bus cool. I will give that a shot.
After the torture you describe in replacing that valve, I'm really, really, really hoping the relay is bad.
Thanks Craig, Phil
I, too feared that one of my supply valves was broken. But they are brass gate valves, not much to go wrong on them. One of them turned normally, 5-6 turns from open to close; but the other seemed to take many turns and still didn't feel like it bottomed open. But upon disassembly, I could find nothing wrong. If I had to replace it, I would have tried to get an OEM valve and only replace the guts, leaving the body in place. No soldering. Anyway, if yours is stuck open that's a good thing.
Rebuild your control valve and see what happens.
HTH
Quote from: TedCalvert on December 02, 2015, 02:32:05 PM
I, too feared that one of my supply valves was broken. But they are brass gate valves, not much to go wrong on them. One of them turned normally, 5-6 turns from open to close; but the other seemed to take many turns and still didn't feel like it bottomed open. But upon disassembly, I could find nothing wrong. If I had to replace it, I would have tried to get an OEM valve and only replace the guts, leaving the body in place. No soldering. Anyway, if yours is stuck open that's a good thing.
Rebuild your control valve and see what happens.
HTH
What normally happens is the gate corrodes in the slot and sticks. Then, someone tries to force it and breaks the stem that connects from the handle to the gate. The gate
remains in the slot and the handle and stem turn but nothing happens.
The handle turns and nothing happens --- kind of like the lights are on and no one is home. BUT to replace the guts you have to have the same brand and vintage valve because nothing else will work. I have seen stripped threads inside the valve on the handle shaft and I have seen the gate stripped inside. I have seen them seized in both the open and closed position. You can try to heat them if they are seized BUT unless you drain them the water will keep you from getting much over 200 degrees.
Good luck Phil I hope you get this solved and thanks for your work on this forum.
Melbo
Phil, I think it is time to consider a Kimberly Stove. Check them out at UnforgettableFireLLC.com or see their ad in our Service Directory. :)
Click here UnforgettableFireLLC.com (http://unforgettablefirellc.com)
I agree the NJT is a strange animal. I have a Eagle Model 20NJT. It is an 12 volt coach, BUT it also had a 24 volt generator just for the fans in the coach heating and cooling. This generator was removed when the coach AC was removed. I found that the circulation pump for the drivers heat was also 24 volt. The circulation pump was located under the aisle floor. I also have a cable controlled valve in the driver's heater supply hose in the top of the spare tire compartment. My Eagle is newer at 1989. Not sure if any of this will help.
Art
Thanks all for the help! All the responses have been quite helpful. The current status is basically 'on hold'. The last steps we tried were to test the relay. First, swapped relays as Craig suggested. Still no-go. Specifically, the relay would never activate when the bus was aired up & the heat was turned on or off. However, in continuing to test, we discovered that the ground was loose to the relay. It appears that the screws were loose and we could jump it - and in a brief moment of glory - the relay clicked! However, the joy was short lived as the test probe then hit the wrong surface and with a large spark, the whole test went dark. >:( Soooo - I've since ordered a new socket for the relay from Luke. The relay has arrived and we're waiting on better weather. Currently snowy, rainy, windy, cold. Taking a week off for the Quartzsite rally. And at the next warm weather we'll see if putting in the new socket, properly grounding it, will fix the heat issue. I'll continue to update, and kind regards to all - hope to meet some of you at the rally.
- Phil
Well, I did meet some of you at Quartzsite and it was a real treat for me. ;D
For the heater repairs, we've repaired the relay socket (driver side, outside panel). We've tested the valve in the middle bay by heating the temperature sensor in the middle bay (removed it from the center wiring chase/ airway) with a heat gun on low temp. Valve functions - or, it is magnetized and we can hear it activating. Sooo - all systems appear to be operating properly. One of the two valves is frozen open (supply valve) back from when this all used to work. BTW - this is how I know it is stuck open. This whole system worked flawlessly a couple years' ago. The valve was always frozen - so it must've been open since I've never been able to move it more than an inch. Next order is to replace that valve guts w/a used valve. Luke @ US coach will hopefully be supplying soon. I been told by Bill they can pull from another MC9. Will validate Monday. Once the valves are both functioning, we'll shut 'em off & rebuild the valve assembly in the middle bay (thank you Clifford for that suggestion). Possibly something is broken in the valve even though it is activating? I have the rebuild kit - also from Luke @ US Coach.
I feel like I'll know the entire heater system pretty well after all this is done. :P
Kind Regards, Phil
My money is still on one of the two gate valves in the engine compartment.
BTW, did you try bleeding the heater core to make sure you don't have an air lock in it?
Thanks Craig - yes, we did bleed the heater core up by the driver. As soon as I loosened the "cap" on the top of the core I had coolant coming out. Later had DD mechanic do the same (don't always trust myself) and he validated - no air pocket.
We'll know soon enough on those valves. I'd love this mystery tour to come to an end. ;D
Kind Regards, Phil
Yes still working on the gate valves so I can fix the coach heat. >:(
To replace the gate valve on the driver side of the bus up in the engine compartment, is there an issue w cutting the valve off at the pipes then putting in a new valve with 1 1/4 pipe nipples on either side. Then using heavy hose & hose clamps to attach the valve? This would be to ease the installation of the valve - much like some of the radiator hoses are attached. It's in a pretty difficult place to reach.
Thanks! Phil
That will work, but be sure the pipe ends all have a rib for the clamps to bite into...
otherwise there is a danger of one of them sliding off and catastrophic overheat shortly afterwards.
Some mechanical external securement in order that the parts don't slip apart is also an option.
happy coaching!
buswarrior
Excellent advice - Thanks buswarrior!!
Kind Regards, Phil
Quote from: plyonsMC9 on May 03, 2016, 09:05:08 AM
Excellent advice - Thanks buswarrior!!
Kind Regards, Phil
is there room for hose nipples ?
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2F3.imimg.com%2Fdata3%2FDA%2FLF%2FMY-3313996%2Fcopy-of-hose-nipple-250x250.jpg&hash=e78f298177cc6b8130393e5acbebb89c45546abe)
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fi00.i.aliimg.com%2Fimg%2Fpb%2F331%2F337%2F409%2F409337331_689.jpg&hash=f8572b6a4c9d5e6d44a159e923d0bef4416f48a0)
Quote from: eagle19952 on May 03, 2016, 12:08:50 PM
is there room for hose nipples ?
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2F3.imimg.com%2Fdata3%2FDA%2FLF%2FMY-3313996%2Fcopy-of-hose-nipple-250x250.jpg&hash=e78f298177cc6b8130393e5acbebb89c45546abe)
I think I've seen those called "hose barbs". Hose ends nor hose clamps slip off of those.
Quote from: Oonrahnjay on May 03, 2016, 01:44:11 PM
I think I've seen those called "hose barbs". Hose ends nor hose clamps slip off of those.
depends who you ask... :)
https://www.grainger.com/product/GRAINGER-APPROVED-Nipple-3LZ94?s_pp=false&picUrl=//static.grainger.com/rp/s/is/image/Grainger/3LZ85_AW99?$smthumb$ (https://www.grainger.com/product/GRAINGER-APPROVED-Nipple-3LZ94?s_pp=false&picUrl=//static.grainger.com/rp/s/is/image/Grainger/3LZ85_AW99?$smthumb$)
Nipple, 1-1/4 In Barb, 1-1/4 In MNPT, Steel
Those valves are soldered onto the pipe. You can unsolder them with a mapp gas torch. Soldering on a new valve is more difficult, but I would recommend that over just
putting on barbs. If you suffer a failure of your heater core or one of the lines up front, you'll have no way to isolate it from the engine.
Find a plumber who does a lot of sweat soldering and ask them to come out and help you.
Get 1 1/4 threaded full port ball valves, thread in pipe and barbed adapter for the proper length. Attach hoses
Rick
Quote from: Oonrahnjay on May 03, 2016, 01:44:11 PM
I think I've seen those called "hose barbs". Hose ends nor hose clamps slip off of those.
Quote from: eagle19952 on May 03, 2016, 02:16:36 PMdepends who you ask... :)
Oh, yeah, nothing's perfect. They can be pretty hard on hoses and, of course, if the clamp breaks or loosens, all bets are off, but they're usually a pretty good solution.
Quote from: eagle19952 on May 03, 2016, 02:16:36 PM
https://www.grainger.com/product/GRAINGER-APPROVED-Nipple-3LZ94?s_pp=false&picUrl=//static.grainger.com/rp/s/is/image/Grainger/3LZ85_AW99?$smthumb$ (https://www.grainger.com/product/GRAINGER-APPROVED-Nipple-3LZ94?s_pp=false&picUrl=//static.grainger.com/rp/s/is/image/Grainger/3LZ85_AW99?$smthumb$)
Nipple, 1-1/4 In Barb, 1-1/4 In MNPT, Steel
Thanks for that. I'm bookmarking that. Some of Grainger's stuff is expensive but they sure have a lot of good components.