Dual climate control blowing heat on AC (DCCV removal instructions in post #107)

[shorod]

Code 1947 indicates that there is a short circuit to ground in the Evaporator Discharge Temperature Sensor circuit. You can start by pulling and the lower of the two temp sensors on the driver's side which is discussed in this thread. The lower sensor is the sensor in question. Check the sensor and wiring for the sensor for a short to ground.

-Rod

[gramman03]

the sensor that you mentioned, where is it and how do i go about removing it? should i just replace the sensor or troubleshoot further?

[shorod]

Originally Posted by gramman03

the sensor that you mentioned, where is it and how do i go about removing it? should i just replace the sensor or troubleshoot further?

Click on the "in this thread" hyperlink from my previous post in this thread. As I mention, although it may not be clear, the Evap discharge sensor is the lower of the two sensors on the driver's side of the center plenum.

-Rod

[howell21]

Originally Posted by shorod

Welcome to the forum!

Your code 2798 means the driver side coolant control valve circuit is shorted to ground. Looks like you pretty much have proof that you need a new DCCV.

-Rod

Hi,
Is the part that I need also called a heater control valve and is it located adjacent to the radiator? One dealer mechanic told me that there are two valves, one located in the dash and one located under the hood. Could someone please clarify?

[shorod]

The Dual Coolant Control Valve (DCCV) is located under the hood near the radiator. It has two valves in it which regulates the flow of coolant to the dual heater core elements inside the car. There is no valve for the coolant flow inside the car/under the dash. Hopefully the dealer technician that told you that will not be the one working on your car.

On older cars, the heater control valve did serve a very similar purpose to the DCCV, but was often vacuum actuated (DCCV is electronically actuated). Someone who's been in the business awhile may refer to the DCCV as a "heater control valve."

-Rod

[howell21]

Originally Posted by shorod

The Dual Coolant Control Valve (DCCV) is located under the hood near the radiator. It has two valves in it which regulates the flow of coolant to the dual heater core elements inside the car. There is no valve for the coolant flow inside the car/under the dash. Hopefully the dealer technician that told you that will not be the one working on your car.

On older cars, the heater control valve did serve a very similar purpose to the DCCV, but was often vacuum actuated (DCCV is electronically actuated). Someone who's been in the business awhile may refer to the DCCV as a "heater control valve."

-Rod

The techician who told me there were two isn't fixing my car. Do you have the part number?

[shorod]

Originally Posted by howell21

Do you have the part number?

It's rare for me to throw anything away, but apparently that's one item that I did.

-Rod

[howell21]

Originally Posted by shorod

It's rare for me to throw anything away, but apparently that's one item that I did.

-Rod

The part i found was YG378-heater control valve by Motorcraft.

[2005LSdude]

Originally Posted by shorod

Well, for the 2004 there is not a designation between the process for DATC with climate controlled seats versus without. Did all V8 models have climate controlled seats?

The manual claims you access the codes with the following sequence:
------------
The DATC module self-test through the front panel display:
can be initiated at any time. Normal operation of the system stops when the self-test is activated.
is entered by pressing the OFF and FLOOR buttons simultaneously and then pressing the AUTO button within two seconds . Record all DTCs displayed.
concludes by reporting all on-demand DTCs. Follow the diagnostics procedure given under ACTION in the DTC index for each DTC given.
reports individual on-demand DTCs as four-digit DTCs (less the alpha character).
will calibrate all the mode doors and check all analog inputs. The DATC module will only report on-demand (hard) faults that occurred while the DATC module was conducting its self-test.
will light all control panel display segments if no faults are detected.
will report individual on-demand DTCs without the °C symbol lit.

To exit the self-test, press the defrost button. This will clear all on-demand codes from the DATC module memory. If no button is pushed, DTCs will continue to be displayed.

Upon exit from the self-test the DATC module returns to operational status. The DATC module executes a hard (cold boot) reset which places the DATC system in the OFF mode.
------------

For what it's worth, I'm claiming success in getting the issue fixed on my wife's LS. My scan tool showed that the Evaporator Core Air Discharge temp sensor was not in range. There were no codes, but the datastream showed no changes in the reading and it appeared to be maxed out at 255 degrees F, even when the vent temp was 45 degrees F. Replaced the sensor and all has been well for 2 weeks of mixed weather.

-Rod

Sorry for slow response , as I have to temp. stop at local library, I've tryed that before and it didnt work, but will try again, there is something I noticed the other day that the air compressor is not kicking off and on.... is there something I can check, it was almost dark when it dawned on me it wasnt clicking off and on..

[shorod]

Is the compressor clutch engaging and staying engaged? If so, that's not really anything to worry about. If it starts cycling rapidly, that would indicate either a low charge of R-134a, an overcharge condition, or some other fault in the system.

-Rod

[gramman03]

thank you for all your help. I removed the sensor and nothing was noticeable to the eye or to a multimeter so i swapped it with the upper sensor on the driver side. AC works fine as far as i can tell this fixed the problem. I ran the self diagnostic again and no errors were shown. Should i still replace the sensor that i moved to the top to prevent future problems??

[shorod]

Yep, I'd suggest you still replace it. You swapped it with the driver's side air discharge temp sensor. The air out of the driver's vent may not regulate as well as it should, and maybe that won't become apparent until winter/cold weather.

Considering that the part is only $16.19 MSRP and is pretty easy to replace, I'd change it out. At least your confidence is high that that will fix your concern completely.

FWIW, my bad sensor looked fine and there was no obvious problem based on a multimeter test. However, my scan tool indicated it was bad in the datastream mode, and the readings followed the sensor when I moved it so I was confident I didn't have a wiring issue.

-Rod

[2005LSdude]

Originally Posted by shorod

Is the compressor clutch engaging and staying engaged? If so, that's not really anything to worry about. If it starts cycling rapidly, that would indicate either a low charge of R-134a, an overcharge condition, or some other fault in the system.

-Rod

Sorry for the long delay in answering again, as I still having to stop at library to use pc. I checked fuses again and the 10A fuse in passenger panel was blown. I replaced it and it did not blow again but still blows hot air. I can now hear compressor cycling. It sounds logical that since that fuse covers AC clutch, coolant control valve, aux coolant pump... that maybe the coolant control valve burned out and blew the fuse. It seems like I read somewhere that the coolant control valve is electronic.. what do you think shorod or any other users.. thanx it will be at least monday before I can get back to this..thanx again..

[shorod]

I think you need to figure out how to get the codes (if there are any) from the DATC unit to see if it guides you to any one particular component. The DCCV is an electronically controlled pair of valves, but everything else in that circuit will also be electronic (hence the need for a fuse) and therefore I'm not sure that I'd say the DCCV is more likely to be the problem than the A/C clutch, coolant pump, etc.

-Rod

[2005LSdude]

Originally Posted by shorod

I think you need to figure out how to get the codes (if there are any) from the DATC unit to see if it guides you to any one particular component. The DCCV is an electronically controlled pair of valves, but everything else in that circuit will also be electronic (hence the need for a fuse) and therefore I'm not sure that I'd say the DCCV is more likely to be the problem than the A/C clutch, coolant pump, etc.

-Rod

Well the ac clutch is cycling so I guess is't not that, the engine has never ran hotter than half way up on gauge (normal), so the coolant pump I guess is doing its thing. But it sure blows very hot air. Is the DCCV? what switches (moves blend door) or blends temps that come out vents? or that a separate thing? Like say on my caravan I can be using AC and say it gets a little chilly inside, I just hit the AC button to turn it off but let the blower keep blowing and it slowly goes to room air temp air blowing through the vents, but the LS is HOT HOT HOT always no matter what adjustments are made. I Never could get the DATC unit to give up a code. (I have disconnected the battery before , several times) bout ready to take it to a dealer, see if they can tell me whats wrong without having them actually work on it. (like saying I have to save up the money before I can get it fixed)... so now what u think? trade it this winter on a very cold day, LOL