Dash heat & defrost diesel pusher?

[Gundog]

How well does your dash heat and defrost work on your diesel pusher. Each year we make one trip in winter and have the same issue the dash heat puts out very little to no heat and does not keep the windshield defrosted very well.

I have shut off valves on the heater hoses and they are turned on. The fan puts out a lot of air but no heat and the windshield fogs bad. Using the coach heat makes it even worse for defrosting due to the propane heat condensation.

How well does your dash heat and defrost work? Diesel pusher only please.

[Belgique]

What kind of shop will work on the AC/Heat systems in a DP? I'd prefer not to use a RV dealer.

[dougrainer]

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

[ExTreker_Vic]

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.

[JRscooby]

Gundog wrote:
The one thing I found which I need to follow up on is the temp of the hose entering the firewall going to the heater one hose is warm to the touch but the other hose is not very warm. This leads me to believe it either has a heater valve that is broken or the heater core maybe plugged. I know some automobiles use a heater valve do these Freightliner units use a heater valve? I plan to remove the 2 hoses and see if I can blow air or water through the core. If the heater unit uses a valve it must be electric operated there is no cable like some of the old autos used.

Getting to the heater unit is a pain I need to remove part of the dash to get access.

To warm the air heat must be removed from coolant in the heater core. This means the return hose should be cooler. Maybe you have a problem with cool air mixing with the heated air?

[Gundog]

dougrainer wrote:

No, they do not have to be turned off. If the Dash heater system is functioning to spec, those valves stay on. Doug

That is good to know thanks Doug.

[wolfe10]

Two reasons for the shut off valves:

Allow you to keep driving if any leak in the hoses to/from the heater core or the heater core itself.

Absolutely prevent hot water from the engine from reaching the heater core. Yes, the valve up forward should do that, but .......

[dougrainer]

Gundog wrote:

Belgique wrote:
Doug, fantastic info. in my 2007 40X we don't have heat and Freightliner Gaffney couldn't solve the lack of air conditioning either. I'll go through the trouble shhoting steps in the manual you identified but my skills are weak. Who works on these? I'd rather not use an RV dealer. It seems I have the Evans Tempcon All Electric.

On the heat side mine has 2 inline ball valves back near the engine make sure if yours has these valves they are turned on. Mine have yellow handles on the valves and they must be turned inline with the hoses. I am guessing in summer time they need to be turned off.

No, they do not have to be turned off. If the Dash heater system is functioning to spec, those valves stay on. Doug

[Gundog]

Belgique wrote:
Doug, fantastic info. in my 2007 40X we don't have heat and Freightliner Gaffney couldn't solve the lack of air conditioning either. I'll go through the trouble shhoting steps in the manual you identified but my skills are weak. Who works on these? I'd rather not use an RV dealer. It seems I have the Evans Tempcon All Electric.

On the heat side mine has 2 inline ball valves back near the engine make sure if yours has these valves they are turned on. Mine have yellow handles on the valves and they must be turned inline with the hoses. I am guessing in summer time they need to be turned off.

[Belgique]

Doug, fantastic info. in my 2007 40X we don't have heat and Freightliner Gaffney couldn't solve the lack of air conditioning either. I'll go through the trouble shhoting steps in the manual you identified but my skills are weak. Who works on these? I'd rather not use an RV dealer. It seems I have the Evans Tempcon All Electric.

[Gundog]

dougrainer wrote:

Gundog wrote:
The one thing I found which I need to follow up on is the temp of the hose entering the firewall going to the heater one hose is warm to the touch but the other hose is not very warm. This leads me to believe it either has a heater valve that is broken or the heater core maybe plugged. I know some automobiles use a heater valve do these Freightliner units use a heater valve? I plan to remove the 2 hoses and see if I can blow air or water through the core. If the heater unit uses a valve it must be electric operated there is no cable like some of the old autos used.

Getting to the heater unit is a pain I need to remove part of the dash to get access.

The Dash Heater and AC system is NOT Freightliner. It is After Market. Freightliner does NOT supply the Front Dash Heater/AC systems. The OEM does. 15 year old unit may be an Evans-Tempcon system. At the front Evap housing will be a sticker that will state Evans/Tempcon. IF so, You Heater Control valve at the Evaporator/Heater Core may be clogged. Common problem with older Evans Tempcon systems. Or the electronic Heater hose valve is inop. Another common problem. Pro Air purchased Evans and this is the Evans breakdown. If the parts look like in this link you have the Evans system. Doug

https://www.proairllc.com/design-engineering/evans-tempcon-guides/

Thanks for the info the controls that it shows in that link look like mine I book marked that page for further reference.

I removed the 2 heater hoses at the firewall and blew air through I got some debris out of the system with air so I rigged up a fresh water hose and flushed the heater putting water in one side and allowing it to drain out the other port after flushing it for a couple minutes and getting a good water stream out I put it back together. It seems to be putting out hot air now. I did not let it run long enough to get to full operating temp because I did not plan on taking it out for a ride and it takes a very long time to get to operating temp just idling. I am thinking i have it fixed our next trip will tell.

[dougrainer]

Gundog wrote:
The one thing I found which I need to follow up on is the temp of the hose entering the firewall going to the heater one hose is warm to the touch but the other hose is not very warm. This leads me to believe it either has a heater valve that is broken or the heater core maybe plugged. I know some automobiles use a heater valve do these Freightliner units use a heater valve? I plan to remove the 2 hoses and see if I can blow air or water through the core. If the heater unit uses a valve it must be electric operated there is no cable like some of the old autos used.

Getting to the heater unit is a pain I need to remove part of the dash to get access.

The Dash Heater and AC system is NOT Freightliner. It is After Market. Freightliner does NOT supply the Front Dash Heater/AC systems. The OEM does. 15 year old unit may be an Evans-Tempcon system. At the front Evap housing will be a sticker that will state Evans/Tempcon. IF so, You Heater Control valve at the Evaporator/Heater Core may be clogged. Common problem with older Evans Tempcon systems. Or the electronic Heater hose valve is inop. Another common problem. Pro Air purchased Evans and this is the Evans breakdown. If the parts look like in this link you have the Evans system. Doug

https://www.proairllc.com/design-engineering/evans-tempcon-guides/

[Gundog]

The one thing I found which I need to follow up on is the temp of the hose entering the firewall going to the heater one hose is warm to the touch but the other hose is not very warm. This leads me to believe it either has a heater valve that is broken or the heater core maybe plugged. I know some automobiles use a heater valve do these Freightliner units use a heater valve? I plan to remove the 2 hoses and see if I can blow air or water through the core. If the heater unit uses a valve it must be electric operated there is no cable like some of the old autos used.

Getting to the heater unit is a pain I need to remove part of the dash to get access.

[carringb]

If you are getting condensation from your propane durnace, GET IT SERVICED ASAP! This is not normal, and indicated a cracked burner compartment.

As for better dash heat... there are many supplemental diesel-coolant heaters on the market, and can supply heat when parked if you add the electric water pump option.

[JRscooby]

dougrainer wrote:
1.You appear to have a 15 year old unit.
2.Dash Heat will be in the 145 to 165 range on a Diesel
3.It is not uncommon on a unit as old as yours to have a clogged Water valve restricting the volume of hot water
4. You need an actual temp measurement of the hot air coming out to determine if you have a problem. Doug

Also need to compare temp of hoses at both ends. Might be loosing heat because the hose runs thru cool area, or because of limited water flow.