Forum Discussion
dougrainer
Mar 04, 2020Nomad
ExTreker Vic wrote:
There are a couple of systems/methods used to control the temperature.
One uses a shut off valve that is operated by the temperature controller on the dash. The other uses a damper to mix the amount of outside air passing through the heater core.
Some are mechanically controlled and others use vacuum to control both the valve and the dampers.
The first step would be to determine which system you have and if it is working properly.
When changing from floor, to dash, to defrost, is the air flow coming out the correct vents?
How is the temperature controlled and is that working?
If all of the above is working the heater core may need to be flushed. This can be done with a garden hose. Disconnect the lines from the core. Connect the garden hose to the core so the flow is opposite direction to normal flow. Run the water through and reverse the lines and run the water again. Do it a couple of times.
Reconnect the lines.
Had a no heat issue with a Jeep. Went though all of the above. After flushing, had to turn the heat down otherwise it was unbearable.
All older motorhome systems(older than 10 years) use a Water valve either cable or electrically operated to open and close the Hot water thru the heater core. Damper type systems which was started about 45 years ago in Automotive Cars, did not come available in RV Class A Motorhomes until the Denso Motorhome Dash AC/Heater systems came on the market about 10 years ago. The OP has a 15 year old Motorhome. Doug
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