[HoosierDaddy]

This heater is not putting out! It is mounted inline in the air duct downstream from the A/C evaporator. This is the heat source for the coach. When I check voltage with it "off" it shows approx. 40 volts at the control box and across the terminals of the element. When I turn it on the voltage goes up to 117 volts. I am trying to determine if it is the element or a controller. The element is not getting hot so I am suspecting it. I am confused by it showing the 40 volts. Can anybody help me determine the real cause of No heat?

[TGDianics]

I assume the evaporator fan provides the air flow for the heater.
Does the evap fan run in the heat mode?
Is the evap coil clean, allowing air to flow?
The heater should have an air flow sensor. No air flow, no power to the heating elements. If you have airflow, check sensor.
The heating elements may have the voltage (V), amperage (I), or ohms (resistance) data marked on them.
If resistance is not provided divide voltage by amperage giving resistance. R= V/I.
Isolate each element from the rest of the circuitry and check the resistance to see if it is close to the value given or determined. If so the element is good.

OR

Isolate each element from the rest of the circuitry and jury rig a connection to the proper voltage. If it gets hot, it's good.

If the elements are good the control circuitry is not.


Good Luck
Tim

[HoosierDaddy]

Thanks Tim.
Yes the evap fan provides the air flow and is operational. There is no air flow sensor in the heater. There is a temp sensor inline (hidden by the coil in the picture) and what appears to be an overheat safety link that u can see to the upper right of the heat box. I will isolate coils and check.

[HoosierDaddy]

   
Here is the culprit. It appears to be a thermal fuse. Can anybody suggest a good source. I'm thinking I probably should replace the temperature control sensor as well.

[bestgenman]

Dean, I've used these guys for parts to repair to the Red Cross Bloodmobiles.  Usually always have what is needed.

https://www.morelectricheating.com/

[HoosierDaddy]

Thanks , Gordon. morelectric can only sell parts for brands they sell. I ended up ordering on ebay. The parts are not identical but will work.
After I ordered from ebay I got a return call from Fred at AAP. They are in Texas . They sell and service HVAC for trucks and busses. He said they have or can get parts for Dometic and Cruisair. Fred seemed very knowledgable. They are on my list of resources for parts in the future.

https://www.aap.com/collections/vendors?q=Dometic

Fred said that the Cruisair basement HVAC boxes were made of aluminum. The early ones used a heat module like my coach. They later incorporated the heat element into the box that contained the evaporator. I told him my boxes are galvanized steel and he correctly identified them as Dometic units. It is interesting to note that my Newell originally had lp furnaces. Two of them were still there when I bought the coach. They were boxed in under the cupboards and the outside vents were removed and had flat covers over the holes in the siding. They had never been hooked up. It appears that there was a change made mid-build. They abandoned the lp furnaces and then added the Cruisair heat modules (4 of them) to the ducts downstream from the A/C evaporator boxes.

I'm wondering if there are any other Newells with the Cruisair heat modules like mine.