Dash Heater Blows Cold Air: Fleetwood Discovery

[rckozy]

Does any one have a fix for the dash heater only blowing cool to warm air. I have a 1999 36t and I would like to fix the dash heater, I know the engine temp stays at about 1/4 on the dash gauge. I do not know if the heater box has a blend door that may be stuck or if it could have an electrical operated blend door. I would think it is a manual operated door because it has a slider on the dash. Both valves in the engine compartment are opened.

[rossboyer]

Near the radiator may be a heater shut off valve. Look for it in the heater hose line. Mine is only visible from underneath.

[wildebill308]

Does any one have a fix for the dash heater only blowing cool to warm air. I have a 1999 36t and I would like to fix the dash heater, I know the engine temp stays at about 1/4 on the dash gauge. I do not know if the heater box has a blend door that may be stuck or if it could have an electrical operated blend door. I would think it is a manual operated door because it has a slider on the dash. Both valves in the engine compartment are opened.

Welcome to the forum.

The first thing to do is follow the cable down from the slider and see if it is opening the water valve to let hot water flow through the heater core.I am confused about what you mean by "I know the engine temp stays at about 1/4 on the dash gauge."

Do you have a infrared thermometer? This is one of the best tools to trouble shoot with.

http://www.harborfreight.com/catalogsearch/result?q=infored+thermoter

See what the temperature is at the top radiator hose and top of the radiator. See what the temp is where the hot radiator hose goes into the heater.

Bill

[rckozy]

I have cleaned the exterior of the radiator and since then the thermostat coolant temp never goes above 1/4, when cold it does return to the cold side on the gauge. I did check the dash cable and it did move the slider for the water valve and I did start the engine and watch to see that all of the buttons moved the linkage for the ac and defrost and the other buttons all worked. I also went and bought a infrared thermometer and I will check the temp tomorrow, I also turned on the engine block heater a couple of hours ago and the top of the radiator is warm to the touch but the heater hoses are still cold and I will go out in the morning and start the engine and check the heater hoses both at the engine heater shut off vales and at the heater.

[wolfe10]

May be more than one issue.

If the engine does not maintain its normal operating temperature, quite likely that the thermostat is stuck open. This leads to poor MPG and carbon deposits in the engine.

Bottom line-- thermostats are cheap and easy to replace-- DO IT.

[kaypsmith]

I agree with Brett, operating any engine, gas or diesel, below normal operating temperature will greatly reduce the life of the engine.

[wildebill308]

OK, I am going to wait till you tell us what the water/coolant temperature is before telling you to change the thermostat. My gage stays in the first 1/4 of the gage for normal operation and it is at the proper temp.

Note the hoses will be cold because the engine isn't running to pump water through them.

Bill

[wolfe10]

Bill is, of course, correct. This may be a gauge issue or real coolant temperature issue.

Has it always read that low?

If you have an IR gun, what does the thermostat housing read after driving at least a couple of miles (such that the engine should be at full operating temperature)?

But, with the major/expensive issues you can run into with operating a modern diesel at cold coolant temperatures, it sure would not take much for me to throw in a new thermostat. In fact, Caterpillar recommends replacing thermostats every three years-- they ARE wearing parts with metal to metal wearing surfaces.