Wet bay heater electric Cargo Heater (System Heat) inoprative

[saflyer]

My wet bay heater doesn’t seem to work. I have removed it and plan to test it with twelve volts directly. I believe I should put positive voltage to two of the wires and negative to one but which. In the picture the plug has red, white and black wires. Which two should I put the positive to?

If it doesn’t work with that power I’ll disassemble it and check the fuse. If the heater works that leaves the snap disc. Unfortunately it is placed so out of the way I can’t find it.

Ed            
‘05 HR Ambassador 

[DavidL]

Is that the heating element side or the power side?

You should be testing with a multimeter.

Check that you have + and - 12 volts when the heater is supposed to be on.  If yes, then check for continuity across the heating element.  If none, then either the element or the "snap disc" (which I assume is a heat switch?)

If you don't have + and - 12 when its supposed to be On, then check fuses and relay.  If fuse is good, then relay might be pitted.  Check that you have voltage to the relay and that it "clicks" when turned on / off.  If it clicks and not +- 12 out of it, then relay is suspect.

Diagnose first, apply voltage later.

[saflyer]

I’m not following all you say. The connector in the photo is attached to the heater. Is that what you mean by heating element side? Your right, I’ll check voltage between black and red wires on other connecter from the coach that the plug in the photo connects to. There should be voltage there regardless of snap disc open or closed. Am I correct?

to test the snap disc I’d have to find it and put an ice pack on it, right? 

Thanks

 

[Gary 05 AMB DST]

Ed, the snap disc is above the tanks and mounted on the plastic wall along the frame rails.

Gary 05 AMB DST

[Gary M]

Mine wasn’t working when I bought our coach. Didn’t test it, just did the fix in the download section advised by Tom Cherry and now it work. The snap disc did fail later and replaced the disc. Bought this off eBay to house the new disc which doesn’t mount flush like the original.

[saflyer]

21 minutes ago, Gary M said:

Mine wasn’t working when I bought our coach. Didn’t test it, just did the fix in the download section advised by Tom Cherry and now it work. The snap disc did fail later and replaced the disc. Bought this off eBay to house the new disc which doesn’t mount flush like the original.

Do you recall the title for the download by Tom Cherry you refer to? I went to downloads and searched for “Wet bay heater” and got nothing.

Thanks

Edited November 24, 2022 by saflyer

[klcdenver]

Attached is wiring schematic for bay heater. Spray the snap disk with a can of air for cleaning computer key boards because it is cold enough to close it. There is a place you can send the heater for repair but I cannot find the name of them. They are listed as a safety company. Sent one there about 4 years ago and it cost $25 and came back looking brand new.

Bay Heater.pdf

[Gary M]

1 minute ago, saflyer said:

Do you recall the title for the download by Tom Cherry you refer to? I went to downloads and searched for “Wet bay heater” and got nothing.

Thanks

Cargo Heater Repair in Most Downloads

4 minutes ago, klcdenver said:

Attached is wiring schematic for bay heater. Spray the snap disk with a can of air for cleaning computer key boards because it is cold enough to close it. There is a place you can send the heater for repair but I cannot find the name of them. They are listed as a safety company. Sent one there about 4 years ago and it cost $25 and came back looking brand new.

Bay Heater.pdf 55.58 kB · 3 downloads

Tried to download your file but can’t. Where is it in files. Thanks Gary 

[klcdenver]

I do not know if it is in files. I have it saved on my laptop. Check your messages because I tried to sen it to you that way also. If not send me your email and I will try that. It is a adobe pdf file.

[Gary M]

2 minutes ago, klcdenver said:

I do not know if it is in files. I have it saved on my laptop. Check your messages because I tried to sen it to you that way also. If not send me your email and I will try that. It is a adobe pdf file.

Got it. 😊 Added it to my 217 drawings.

Edited November 24, 2022 by Gary M

[cbr046]

I'll bet a dollar if you take the heater apart (4 screws on the back), open it up to find a thermal fuse crimped between the supply and the elements and put an ohm meter across it you'll get an infinity ready (should be 0 ohms).  That thermal fuse (20A / 184C) is blown. 

There are articles written on replacing that fuse, which is under rated to begin with, if you search for it.  I split the elements into 2 sets with an independent 20A / 184C fuse for each set.  It worked great one night.  The next night one of the fuses blew leaving 2 of the 5 elements still working.  Theory is the crimp wasn't good enough (used vice grips vs a "real" crimper) and transferred heat into the fuse. 

Fuses and crimps are available from Newark Electronics.  Don't be like Bob and use vice grips.  You'll need a ratcheting crimper (or better). 

- bob

 

 

 

 

[saflyer]

24 minutes ago, klcdenver said:

Attached is wiring schematic for bay heater. Spray the snap disk with a can of air for cleaning computer key boards because it is cold enough to close it. There is a place you can send the heater for repair but I cannot find the name of them. They are listed as a safety company. Sent one there about 4 years ago and it cost $25 and came back looking brand new.

Bay Heater.pdf 55.58 kB · 7 downloads

Got the wiring diagram. The diagram indicates there are two lights for activation, one in the switch to show switch on and a separate one to show the snap disc is activated. Am I right. My understanding of my system is there is only one light, the one in the switch and it only comes on when the snap disc closes and the heater is activated. 
Thanks

Edited November 24, 2022 by saflyer

[klcdenver]

You are correct unless the switch bulb has burned out. You can put a jumper across the snap switch and if the fan blows then you will know if your switch bulb is good or not.

[saflyer]

1 hour ago, saflyer said:

Got the wiring diagram. The diagram indicates there are two lights for activation, one in the switch to show switch on and a separate one to show the snap disc is activated. Am I right. My understanding of my system is there is only one light, the one in the switch and it only comes on when the snap disc closes and the heater is activated. 
Thanks

Just went to coach and got some pics.First, the only thing I found behind the wet bay panel and on the plastic covering the frame rail (at least that’s what I think I’m looking at) is in the picture. The wires lead to something in a hole in the plastic cover. Could that be the snap disc? It doesn’t look like I expected. (First two images)

I then looked at the switch. So, should the light in the power switch illuminate any time the switch is in the on position and there be a light in the red panel below “ Active” come on if the snap disc closes and activates the wet bay heater?

[Gary M]

5 minutes ago, saflyer said:

Just went to coach and got some pics.First, the only thing I found behind the wet bay panel and on the plastic covering the frame rail (at least that’s what I think I’m looking at) is in the picture. The wires lead to something in a hole in the plastic cover. Could that be the snap disc? It doesn’t look like I expected. (First two images)

I then looked at the switch. So, should the light in the power switch illuminate any time the switch is in the on position and there be a light in the red panel below “ Active” come on if the snap disc closes and activates the wet bay heater?

Yes power should light up and then when temp gets below 40 degrees, active light then comes on. Take a bag of ice cubes and place on snap disc to activate. If all is well, this should happen. Follow what CBR46 said to test. I also had to replace power switch and active light at one point.

Edited November 24, 2022 by Gary M

[cbr046]

3 minutes ago, saflyer said:

I then looked at the switch. So, should the light in the power switch illuminate any time the switch is in the on position and there be a light in the red panel below “ Active” come on if the snap disc closes and activates the wet bay heater?

Correct, but in my coach the lights inside both the switch and "active" lamp were both out.  I've since replaced them (and a few other indicator lights). 

As I said above, 99% sure if the fan in the bay heater is running and there's no heat the problem is that fuse inside the heater.  At night you can see the heating elements glow.  Easy to disassemble and check the fuse. 

- bob

[saflyer]

1 hour ago, klcdenver said:

You are correct unless the switch bulb has burned out. You can put a jumper across the snap switch and if the fan blows then you will know if your switch bulb is good or not.

If I could reach it. At best I could get one arm in there reaching through the hole left after removing the tank quantity indicator panel. But I couldn’t see anything at that point.

[Gary M]

22 minutes ago, saflyer said:

If I could reach it. At best I could get one arm in there reaching through the hole left after removing the tank quantity indicator panel. But I couldn’t see anything at that point.

Mine is easy to access as it is on left wet bay wall just above water pump.

[klcdenver]

If you cannot reach the snap disc to check it, just get you another one and locate where it is accessible. Looks like your wires are terminated with a female spade so you should be able to pull the wires off.

[saflyer]

29 minutes ago, Gary M said:

Mine is easy to access as it is on left wet bay wall just above water pump.

Oh how I wish.

[Tom Cherry]

6 hours ago, saflyer said:

My wet bay heater doesn’t seem to work. I have removed it and plan to test it with twelve volts directly. I believe I should put positive voltage to two of the wires and negative to one but which. In the picture the plug has red, white and black wires. Which two should I put the positive to?

If it doesn’t work with that power I’ll disassemble it and check the fuse. If the heater works that leaves the snap disc. Unfortunately it is placed so out of the way I can’t find it.

Ed            
‘05 HR Ambassador 

There is a Triggering circuit.  The red wire, I believe is the POWER.  The white or black is the thermostat signal.  The other is ground.  You can test it by having a dual 12 volt wire.  You feed 12 VDC into the thermostat or trigger signal.  Then the power wire will be engaged and the heater will function.

These heater were “revised” about the time your MH was made.  They added a “safety valve” thermofuse.  BAD DESIGN and NO FIELD TESTING. Here is the tix if your heater doesn’t work.  This has been mused by many and works….

OK….from the top.  The HEATER is the first thing I would test.  I have attached the file on HOW to fix it.  I also pulled a print that is, to me a little easier to read and follow.  This is HOW to test the heater….

RED is the MAIN POWER.  
YELLOW is the Trigger or Thermostat wire.

BLACK is ground.

SO….put 12 VDC to the RED.  You will need a 20 AMP source for the heater.  Actually, that is WRONG.  The heater is OVERRATED.  It barely pulls 15 Amps…..despite what the plate data says.  This is REAL WORLD testing,  if the heater works, THEN a you need to test the circuits.  Monaco did some weird things.  Follow the prints.

Most of the time there was a snap disk thermostat hanging down.  It is about 3/4” in diameter and maybe 1/2” high.  It MAY have a clip or an ear to mount it which is more like a bracket.  The disk is or round portion is the SNAP.  Folks have used a cup of melting ice wate and put a plastic bag over the disk and dropped it into,the water.  Others have gently dangled it in the water as it is supposed to be sealed.  It has to be below 40 or so for it to come on,

The switch is a Single Pole single throw switch with an indicator lamp inside.  The circuit works like this.

There is a Black wire wire that is the GROUND for the indicator (inside the switch). That is also connected to the Ground of the IN SERVICE light beside it.  Red is the incoming power to the switch. The Blue wire is supplying POWER to the Snap Disk thermostat.  It is merely an ON/OFF a switch.  What is HARD auto see on the photo is the YELLOW Wire.  That is the OTHER side of the IN SERVICE light.  If you look at the Thermostat, the OUTGOING power is YELLOW.  That is the wire (on the heater) that is now (assuming the thermostat is closed or calling for heat) that goes to Yellow or Trigger wire on the heater,  it also goes BACK up to the IN SERVICE LIGHT.

SO….main switch is on.  Power is going to the thermostat.  The internal light on the switch will be on also.  Then when the thermostat CLOSES, the yellow wire has POWER. It triggers the internal control board and turns on the heater.  It also sends a 12 VDC signal back to the INSERVICE light,  if the heater is heating, the bay will get hotter and the thermostat will open…

Now you know.  A n easy work around is a metal trouble light with a 60 Watt INCANDESCENT bulb and a cheap “freeze Protection” plug in switch from Amazon.  These switches plug into an extension cord or receptacle and have 2 Receptacles on them.  There is an internal thermostat that is close to the snap disk one,  when it gets hot enough, it will shut off.  The theory is that the 60 watt will stay on and provide enough residual heat.  If you want to match the output of the 12 VDC, then two 75 watt bulbs…..in a trouble housing plugged into the freeze protection unit,  I have 2 bare 60 watt bulbs hanging in my pump house and one of the freeze protection units,  that way, if ONE bukb burns out, the other is there…

Good Luck.  Look at the print or photo and the how to FIX the heater.

ONE WORD OF CAUTION.  In order to crimp the Ferrells, you need a ratcheting crimper.  You can’t get enough leverage with a pliers type.

 

[BradHend]

I originally thought my wet bay heater never worked when I first bought my coach. It wasn’t until one frigid night (about 3 degrees Celsius) I noticed that the light came on and upon checking, the heater was indeed working.  
just saying, are you sure it doesn’t work or is it just not cold enough?

[jacwjames]

I moved the snap disc so that I could get to it easier.  If I think I may be in cold weather I test the the system by unplugging both of the wires from the snap disc and use a male to male connector which will turn the heater on.  I then check to make sure the indicator light on my monitor panel is coming on. 

Last year I was in pretty cold weather, I can't see the monitor panel from my bed and I'd get up and check occasionally to see if it was on, never did see it come on which led to restless nights.  So after the trip I actually installed another indicator light in the bedroom so if comes on I'll have a better chance of seeing.

[saflyer]

1 hour ago, BradHend said:

I originally thought my wet bay heater never worked when I first bought my coach. It wasn’t until one frigid night (about 3 degrees Celsius) I noticed that the light came on and upon checking, the heater was indeed working.  
just saying, are you sure it doesn’t work or is it just not cold enough?

That’s a very good question. Short answer, no, I’m not. It there was a reasonable way to test it it sure would be nice.

Edited November 25, 2022 by saflyer

[Tom Cherry]

27 minutes ago, saflyer said:

That’s a very good question. Short answer, no, I’m not. It there was a reasonable way to test it it sure would be nice.

Read my response,  either pull out the heater or test the circuit,  the heater is the usual suspect.  If you want to test, then you will need to find the snap disk and dangle it to below freezing,  it will not come on until the temp drops to around 40 or so.  These are IMPRECISE and cheap snap disks,  it you don’t  get the heater working when it is in melting ice water 31.5 DF, then the disk is bad.  However, since you don’t know if you have power to the switch, I think…..is the indicator light on in the switch.  If so, then you should have the INSERVICE light on,  BUT if that light is bad, you don’t know.  

Try this,  put the snap disk barely in melting ice water,  put a VOM on the terminal that plugs into the heater.  You need the One that the Yellow wire plugs into,  then ground out the other one,  if you get the snap disc COLD, you will have voltage going to the Yellow wire.  No VOLTAGE….there is a problem in the MH circuit.  VOLTAGE to the heaters Yellow wire…..then you got a bad heater with the thermodisk fuse blown….a common occurrence,  

That is as simple as it gets….