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 > Dash heat & defrost diesel pusher?

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Gundog

Ridgefield, Wa

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Posted: 03/01/20 11:11am Link  |  Quote  |  Print  |  Notify Moderator

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.


2005 34' Expedition Cat C7 Allison 3000

dougrainer

Carrolton, Texas

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Posted: 03/01/20 02:53pm Link  |  Quote  |  Print  |  Notify Moderator

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

Ridgefield, Wa

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Posted: 03/01/20 05:02pm Link  |  Quote  |  Print  |  Notify Moderator

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.

Belgique

Hickory, NC

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Posted: 03/02/20 05:58am Link  |  Quote  |  Print  |  Notify Moderator

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.


Hickory, NC
2007 Fleetwood Discovery 40X


Gundog

Ridgefield, Wa

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Posted: 03/02/20 09:24am Link  |  Quote  |  Print  |  Notify Moderator

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.

dougrainer

Carrolton, Texas

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Posted: 03/02/20 12:37pm Link  |  Quote  |  Print  |  Notify Moderator

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

wolfe10

Texas

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Posted: 03/02/20 01:23pm Link  |  Quote  |  Print  |  Notify Moderator

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 .......


Brett Wolfe
Ex: 2003 Alpine 38'FDDS
Ex: 1997 Safari 35'
Ex: 1993 Foretravel U240

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Gundog

Ridgefield, Wa

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Posted: 03/02/20 06:29pm Link  |  Quote  |  Print  |  Notify Moderator

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.

JRscooby

Indepmo

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Posted: 03/03/20 04:50am Link  |  Quote  |  Print  |  Notify Moderator

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?

ExTreker Vic

ct

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Posted: 03/03/20 02:06pm Link  |  Quote  |  Print  |  Notify Moderator

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.

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