No heat at dash

CapnDirk · December 17, 2016, 07:25 PM

Well, I go out to the MH now and then to start it and warm it up. Yesterday, I have no heat (had not used it since purchase). I have always hated the vacuum operated systems and could see they were going to be a problem long ago.

First thing, check for vacuum supply at the reservoir. Got vacuum going in and out, and got lucky to find the plastic line split and almost in 2 pieces. A trip to autozone and I replaced the line from the reservoir to the check valve (which I checked). I now have vacuum at the heater control, but none of the buttons actuate anything.

The control is the standard push button unit that many of us (including Rick) have on our rigs. I could see one of the outgoing lines might be bad, but doubt all three would go.

Any thought would be appreciated.

Rickf1985 · December 17, 2016, 09:10 PM

Find the line where it comes up through the floor of the dash and follow it to the heater control. It could have pulled the vacuum plug assembly off of the heater control. Or the line could be broken behind the dash also. On mine the vacuum plug was partially pulled off.

CapnDirk · December 18, 2016, 11:01 AM

Thanks Rick. If I were so lucky

.

I have verified that after having replaced the broken black line from the reservoir to the multi tube head at the heater control I do now have vacuum at that plug. However, there is no action elsewhere when any of the buttons are pushed.

I have some of the old black plastic line from the replacement, so I'm going to remove the plug at the control and insert it into the black hole and any of the others going out to the actuators. I thought of that last night after posting. This would effectively jumper the connection bypassing the control unit.

I see in another post from Dave that as of 2 years ago the vacuum switches were still available.

Rickf1985 · December 18, 2016, 11:17 AM

I remember that and I do remember that they were not GM switches. I want to say they were Dodge but I do not remember. Do a search for "heater switches" on the forum. I am going to be tied up for a while with a generator issue on mine so I may not be on for a bit.

M & J · December 18, 2016, 11:47 AM

Try searching for "heater control" also. I think they were Dodge.

Dave posted a thread on identifying and sources perhaps.

CapnDirk · December 18, 2016, 12:10 PM

I found it, they were Dodge from about late 70's to late 80's give or take.

Rick, I had the same problem on my genny, if you don't know the usual fix, let me know.

Rickf1985 · December 18, 2016, 12:14 PM

PM me what you did, and I will see if it jives with what I am thijnking. No matter what it has to come out to work on it.

CapnDirk · December 18, 2016, 07:09 PM

Well, I made progress. After replacing the multi faceted (read all cracked up) vacuum supply line and seating the block of hoses ALL the way in (thanks Rick) I have actuation of the vent directors for changing def, heat, vent. However, still no heat. Rather than chase my tail, I figured the smart thing would be to top off the coolant/anti freeze. I can not get the radiator cap off, and not sure I should. I've added coolant to the overflow bottle, but even that being the highest elevation, it is lower than the heater core. So what to do about an air pocket?

Two other things.

1. I have no high fan, and am aware this would be the relay. Does anyone know the location, and maybe a part number?

2. I have located the vacuum shut off valve (turns off water to heater core when AC on) and it is hot on incoming side from engine, and mildly tepid on the out side. Sending vacuum to it does operate the arm, but I can't discount the possibility of A. low coolant and an air pocket, and B. the arm inside the valve snapped and it's not opening even though outward appearance seems that it is. A source for that should I need it would also be appreciated. It is a single in and out inline valve. 3/4 hose.

Thanks

M & J · December 18, 2016, 07:17 PM

That's just 1.
These older coaches used a flow control valve in the coolant line instead of a diverter in the airbox. Can you trace the cable from the Temp slider and see what its connected to? In ours the cable and water flow valve were corroded and wouldnt budge.

CapnDirk · December 18, 2016, 07:19 PM

Thanks M J, was still editing when you posted, you may want to re-read. Appreciate the input.

M & J · December 18, 2016, 07:25 PM

Air pocket or clogged heater core. Just back flushed the core in our 91 K Blazer yesterday because of low heat output.
And yup. Answered while being edited.

M & J · December 18, 2016, 07:40 PM

I just searched the forums for heater control valve and found several threads.

CapnDirk · December 18, 2016, 09:07 PM

Traced the cable from dash to a door on the heater box, so it is not a valve control.

Searched the forums too, but only came up with water control valve, and not the vacuum operated ones to shut off water flow when in AC mode. Ebay has aftermarket ones from Ford and other manufacturers, and may go that route just so that it's fresh.

Anyone with info on how to top off the coolant when heater core is above fill level, operators are standing by.

M & J · December 18, 2016, 10:04 PM

Your model has a blend door for heat control. Can you tell if the hose is hot beyond the valve? Where does the core return hose go and from where does the core get the heated antifreeze?

I googled burping heater core and got a number of responses. Most model specific. Some showed removing the "high side" hose and running water through it then reconnecting it while flowing.

CapnDirk · December 18, 2016, 11:33 PM

The vacuum operated shut off is hot on the in side and mildly warm on the outgoing side. Ingoing side is about 18 inches from a nipple on the intake manifold.

I've ordered the vacuum valve (can't get hurt for 9 bucks and free shipping), and I'll pull the outgoing side tomorrow to see what I get.

I've been googling for hours and can't find anything on the proper way to add coolant and burp the system. But, have not used the word burp

Rickf1985 · December 19, 2016, 08:55 AM

How much coolant is in your bottle? Is the tube in the bottle good? they tend to rot and then they pull air from the top instead of coolant from the bottom. Adding coolant to the bottle is the proper way to top off the system but the system has to cycle through several heat cycles to push air from the radiator into the bottle and pull coolant out of the bottle. It does most of this on a complete cool down overnight. Be sure the little hose from the bottle to the radiator is sealed at both ends and not collapsing and be sure the hose in the bottle goes almost all the way to the bottom of the bottle. The fact that the tube is hot in and cool out means you are transferring heat and you are not getting enough flow or enough water.

CapnDirk · December 19, 2016, 11:16 AM

I had not thought of checking the dip tube on the bottle Rick, thanks. The bottle is in a bad place, Looks like a French baggette mounted horizontal BEHIND a piece of tubing so you can't see the coolant level.

The hot water on the in going side of the vacuum valve and cool on the out side suggested EITHER a bad valve or air pocket. New valve should be here by weeks end.

Still looking for any info on part number for fan relay (no high speed). Have looked over Dave's info, and a lot of Gooogling and no luck.

Rickf1985 · December 19, 2016, 11:56 AM

Fan speed is controlled by a resistor that is mounted front and center on the heater box under the hood. Three wire plug on a flat plate screwed to the box, the resistor cooling coil is inside the box. It is 50/50 on a bad resistor or a bad switch. Dodge sometimes did not use a resistor and all of the amperage went through the switch and the switch burned up fairly often but I am sure I remember seeing the resistor on mine.

CapnDirk · December 19, 2016, 03:35 PM

Thanks Rick. The fact that I have lower speeds on the fan but no high suggests the relay. Lower speeds go through the the resistor then through the relay. High speed goes full 12V through the relay via the latch circuit being energized from the high speed setting on the dash switch. So, the relay is a fork in the road so to speak, lower speeds one fork to the fan motor via resistor, high speed only, the other fork.

Now if I could just find the damn thing

. I've worked on 70's British imports I could get my hands into easier than this Freightliner sized thing!

Rickf1985 · December 20, 2016, 09:45 AM

Like I said, Dodge/Chrysler a lot of the time did not use a relay so the switch burned up. Try jumping the wires on the plug at the switch and see if you get high speed that way. If you do then no relay.

CapnDirk · December 20, 2016, 09:51 AM

Thanks, Should have thought of that. sending 12V to the high speed line would tell if something is in between.

CapnDirk · December 27, 2016, 10:43 PM

D:oH! D:oH! D:oH! Well, i go around from the heater problem to the high beam problem to the wiper problem so as to even out the stress

I was considering making this a separate topic, but need to close this with the solution. Management may want to separate it.

Heater issue progress was made recently by replacing the vacuum line from the reservoir to the control at the dash which got the vents changing on request. Then today it got real wonky. Part of the problem was no high speed on the fan. On lower speeds the power source goes through the switch to the resister to determine speed, to the heater relay, then to the fan. High speed is a separate power source to the switch, then the relay, then the fan (thanks to Dave for posting a schematic). With many posts here and there saying the relay had caused a loss of high speed I ordered the $6 relay that took a week to get here, plugged it in, and nothing. So, we now set off with the 12V probe and voltmeter to chase the supply wire from the relay to the source.

First stop in reaching under the dash and trough the dash with the radio bezel off and the speedo cluster out is an inline 30A fuse holder. Aha! Nope, the fuse is good. Next stop is the wire goes up and over and down into the circuit breaker box to a 30A breaker. Huh? Why both? 1 foot from each other. I check the outgoing side of the breaker and nothing, Aha! Nope, breaker is good. But shouldn't these 8 gauge wires on the other side of the breaker have power?

Back to the worthless wiring diagrams which do show the breaker box and those supply lines going from the heater fan breaker, to the dual battery solenoid! Huh? What the hell for? So I trip the dual/mom rocker switch to get a few seconds of power at the breaker and then nothing. I can sometimes hear the solenoid, but decide to jumper the solenoid on the firewall and see what i got with my jumper cable. I do so, go inside and nothing! Huh? I'v jumpered the solenoid Battery cable to the other side where the 8G wires go to the breaker.

!!! 15 minutes later I have the cables removed, cleaned and back on. I now have power at the breaker. I remove the jumper cable, and nothing. I hit the dual battery switch and nothing. I hit momentary and bingo!. So now i have a bad battery switch. High fan speed works, but is supplied by the battery solenoid being kicked in?

All of this is stock. So, back to the whining diagram which shows the coach batteries through the disconnect to the solenoid on one side and two 6G wires to the breaker box. On the other side of the solenoid it shows two 8G wires that go to the breaker box (so far so good on what I've found being correct) AND cables to the chassis battery and starter... which are not there! The only other wire on that side is the cable to the leveling jack solenoid. This explains why i couldn't get the coach batteries switched in a couple weeks ago when the chassis battery was dead. What a day.

Anyone know where I can get a replacement battery switch? I going to go talk to Jack now.

legomybago · December 27, 2016, 11:35 PM

Well, I can say one thing......at least you understand your electrical system a little better now!!! Your last post was well written in describing how we learn about our rigs a little more each time we trouble shoot a goofy issue. I have no idea where you get that switch.

DaveVA78Chieftain · December 28, 2016, 05:05 AM

Winnebago Parts Catalog

CapnDirk · December 28, 2016, 11:18 AM

Lego: Thanks, that was the idea. So many people in forums ask a question, get answers and then don't post what the solution was so others can benefit. Drives me nuts to read post after post because someone else had the same problem, and then they disappear.

I do need to buy another battery cable for the solenoid to the chassis battery. Wiring diagram shows battery cable --> chassis battery to solenoid, and solenoid to starter. Since the existing cable is battery to starter, I'm wondering if I can go solenoid to battery, but leaves me with how to connect two cables to the battery terminal.

For the life of me I don't understand the need for TWO breaker/fuse protections, and why pick up the source out at the battery solenoid when the fuse panel was right there where they ran the wire over it to the breaker box. So many trucks and cars didn't need to run a separate wire out to the battery for high speed on the heater fan.

Dave: Thanks for the catalog. $70 for a 10A rocker switch (multiple sources) is nuts. But I did find a seller that said they were the same for 70s 80s and 90s. I'll see what I can find. Stock or otherwise.

So what to do today, wipers or high beams Hm?