Climate system.

[Velo]

I have a question about the climate system, I do know the DCCV has been discussed many times but what I like to know where the DCCV gets the signal from. The information I did get is that the input comes from the climate control system but like to know what makes the DCCV constantly switch and if it is located in the climate control unit or elsewhere.
TIA Jake Houtop :slam

 

[joegr]

I'm not sure that I understand your question, so if I answer the wrong questions, please forgive me...

The DCCV has two 12V solenoid coils, one for the driver's side water valve, and the other for the passenger's side. Both valves are fully open when no power is applied, and fully closed when power is applied.

The DTAC module supplies/modulates power to the valves. To be able to set either valve to particular partial open position, the DTAC uses PWM (Pulse Width Modulation). This means that it rapidly turns the power to the solenoid on and off. If it is on for half of the time, the valve should hover at half way open/closed. If on for 2/3 of the time, then the valve would be 2/3 closed (or 1/3 open).

The DTAC decides how much to open each valve based on four factors (as far as I know). Outside temperature, inside temperature, set (desired) temperature, and heater core outlet temperature for whichever side we are talking about (driver or passenger). I think that based on the first three factors, it decides what temperature it wants the outlet air to be on each side. It then reads the heater core outlet air temperatures on each side and decides if it needs to open or close each valve more or less than it currently is.

 

[Velo]

I'm not sure that I understand your question, so if I answer the wrong questions, please forgive me...

The DCCV has two 12V solenoid coils, one for the driver's side water valve, and the other for the passenger's side. Both valves are fully open when no power is applied, and fully closed when power is applied.

The DTAC module supplies/modulates power to the valves. To be able to set either valve to particular partial open position, the DTAC uses PWM (Pulse Width Modulation). This means that it rapidly turns the power to the solenoid on and off. If it is on for half of the time, the valve should hover at half way open/closed. If on for 2/3 of the time, then the valve would be 2/3 closed (or 1/3 open).

The DTAC decides how much to open each valve based on four factors (as far as I know). Outside temperature, inside temperature, set (desired) temperature, and heater core outlet temperature for whichever side we are talking about (driver or passenger). I think that based on the first three factors, it decides what temperature it wants the outlet air to be on each side. It then reads the heater core outlet air temperatures on each side and decides if it needs to open or close each valve more or less than it currently is.

Thank you much. That is exactly what I wanted to know and do you believe the PWM is housed in the climate control??? TIA.
Have a great evening. Jake Houtop

 

[joegr]

Thank you much. That is exactly what I wanted to know and do you believe the PWM is housed in the climate control??? TIA.
Have a great evening. Jake Houtop

Yes, the circuits that drive the PWM are inside the DATC (I know, I miscalled it the DTAC above). I've taken apart and modified some other Ford climate controls and I could tell you what chips were used in those, but I haven't had cause to look inside the LS's control.
The service manual gives procedures to determine if the fault is the DCCV, the wiring, or inside the climate control assembly. Let me know if you need those.

 

[MDLS04]

AC problems

Sorry to jump into the maiddle here of Jake's thread but Iam right there also. I have hot air all the time out of both sides and I have replaced the DCCV..still hot! I would appricate any info on next step
John

 

[joegr]

I would start by running the DATC self diagnostics (search here for diagnostics for how). Let us know what if any codes come up. Also, there is a fuse that the DCCV sometimes blows when it fails, check that. (Sorry, I forget which one.)

 

[Velo]

DCCV replaced

I would start by running the DATC self diagnostics (search here for diagnostics for how). Let us know what if any codes come up. Also, there is a fuse that the DCCV sometimes blows when it fails, check that. (Sorry, I forget which one.)

Hi Joegr.
Well I finally replaced my DCCV, it was a piece of cake on my 3.0 ltr. 6 cylinder and I even used the original clamps after making a proper set of pliers for it.
Also checked the old one and found one of the winding was shorted inside the coil.
Works nice now and thank you again for all your messages about the working of the DCCV.
By the way the fuses are #20 on the right side kick panel 10 Amp. and #1 in the fuse panel under the hood also 10 Amp. I did not have to replace them which was a real surprise with one coil on the DCCV being shorted.