I'm still learning about the D2 so bare with me here. On a recent road trip my heat was playing games with me while driving. At first I set the auto feature to 20 on both sides. This was before I figured how to switch the read out to Fahrenheit. The heat would come out fine for awhile then randomly start blowing cold air. So I assumed the "auto" feature was being screwy I set the fan speed and air direction manually. Same symptom. The system would randomly switch from hot air to cold air and back again with no change in read out from the panel. There seemed to be no pattern or reason for the change. It was snowing and 20 degrees out at the time so this was less than fun.

Is there a diagnostic procedure to this system? All the threads I've searched turn up a panel that doesn't work or in op. Or a no heat issue from a thermostat. My control panel seems to be working fine. And I know I have heat as long as the system allows it to come out. Also is there a way to silence that stupid beeping everytime I push a button?

 

I had a similar problem where my heat would stop working if I came to a stop but it would work while I was driving or when I revved the engine up. It ended up being air in the lines. I'd say try bleeding the cooling system again, that could very likely be your issue.

 

Press "auto" and "reclining man"/fan zone button and hold down till flashing stops. It will show you fault codes if you have any.

 

Have you tried setting it on "ECONOMY" instead of "AUTO" mode , & see what happens,?
I think thats how you need to set it if you want heat,,
If is doesn't work after putting in ECONOMY mode, you might have air in heater core,
( I am just guessing),,

 

I'd be on board w air in the system if changing the settings around didn't result in heat elsewhere. So if it's cold out of the vents and I switch to floor it's hot again. And vise versa.

 

typicality cheap 20 century a/c control, instead of maintaining the proper temp. the run the heat and cooling at the same time, if it starts over heating the ac comes on.
That's why the have no heater control valve.
I usually will hit the econo. button to keep the ac from coming on in the winter.

 

This is actually the system working correctly. Once the system reaches the predetermined temperature, it will start using both cool from the dash vents while still pushing heat out of the floor vents to regulate the temperature. If the cool air coming out of the vent bothers you trying turning the air temp up a bit to keep the system from cycling out cool air to keep it from getting too hot.

The system in the truck is not the best in terms of how it works. It has I believe 4 fan speed settings instead of a variable fan. If the fan at the lowest setting is pushing too much of one kind of air to maintain the current temperature the system will mix the other type in to regulate. This is why on a cool spring day with the a/c on you can have cool air coming from the vents at the same time as heat coming from the floor.

Only way to keep the system from functioning this way is to set things manually. So instead of using a temperature set the system to max heat or cool. The choose the fan speed you want.

 

In manual mode? Read in Electrical Library the other day auto mode has 30 speeds.

......

 

Hard to believe that's the way it's supposed to work. But I see your logic.Makes sense I suppose. Any thoughts on the beeping?

 

Here's a video