On my 06 STR my air conditioning was working just fine until I started messing with my data link connector to try to solve a bus problem I posted about in a different thread.

but since I messed with that data link connector and the bus wires at various modules I seem to be having a problem with my AC that doesn’t make much sense.

My climate control module has been modified to include two resettable fusible components in place of the charred wiring board traces.

My AC was working just fine recently as I said. I also have a new compressor. Super cold.

now when I start the car up initially and turn the AC on it blows out nice and cold just as you would expect. If I’m sitting there at idle it will stay blowing cold for however long I sit there. If I’m sitting there at idle it will stay blowing cold for however long I sit there at idle. But if I try to drive or if I give it any amount of throttle it starts sending heat into the heater box so my vents blow out pretty warm air and will continue to blow out continually warm air until I shut the car off for a period of time. Then when I restart it once again I have ice cold air for as long as I sit there at idle but if I give it any amount of gas the dual climate control heater valve start sending hot coolant into the heater core.

any ideas? I haven’t measured voltages occurrence at the heater valve yet because it’s a pain in the *** to get to but I’ll eventually get there

 

Hmm, this is an odd one.

If you pull over and continue running the engine at idle, the problem continues, right? Pop the hood and see if the face of the compressor pulley is spinning or stationary.

If the pulley face is stationary, the compressor has been commanded off for reasons unknown. From post #5 of the troubleshooting guide, any of the following conditions will inhibit the command for the compressor to run. One major catch is you have no surefire way to know which condition(s) is inhibiting the command. You will have to run through a process of elimination:

A) Engine starter engaged

B) Wide open throttle

C) Over 5882 RPM

D) Under 400 RPM (V8) or 450 RPM (V6)

E) Failsafe cooling mode (V6 only) - Not applicable to your model

F) Power steering pressure high (compressor disabled for 5 seconds only) - Make sure steering wheel is at neutral position. This is
not a likely fault, because it is canceled after 5 seconds.

G) Exterior temperature below 27F - Check display on control panel.

H) Evaporator discharge temperature below 34F

I) High side pressure above 420 PSI - Not very likely, unless the AC pressure sensor has failed and is always indicating extremely high.

J) Low refrigerant quantity - The AC pressure sensor has detected low pressure.

 

Part 2:

Try the test of the DCCV as detailed in post #2 of the troubleshooting guide. I give two versions you can do. See if the DCCV starts dumping heat into the cabin when you increase RPM.

Remember, the heater is fed by an abundant source of energy, i.e. the engine cooling system. Meanwhile, the AC system is of finite capacity, without a lot of reserve. If the heat and AC systems get in a tug of war, the heater will win every time.

One possibility is the DCCV is closing, but barely so. Increase the RPM, and this also increases coolant flow. I've noticed the heater output is marginal at idle, which I believe is due to minimal coolant flow. When heat is requested, as soon as I rev the engine, the heater output comes back to life. Maybe this increased coolant flow is pushing open a tired DCCV, and it can't fully close again until the engine is turned off and coolant flow ceases. Are you seeing the problem on both sides or just one? It's not likely both sides of the DCCV have failed to the same extent at the same time.

 

The compressor clutch is engaged and the compressor is definitely pumping.

i’m thinking that maybe those resettable fuses that are in the climate control module to replace the burnt out copper traces I may be getting very warm because the DCCV is pulling too many amps so when I put it in the gear and give it a little bit of juice those resettable fuses pop And they don’t reset until after I shut the car off.

It’s definitely a situation where the DCCV was closed until I gave it some throttle because I can feel the supply lines going to the heater core and before throttle there’s one hot to warm lines and after throttle it’s three extremely hot lines.

As for the vent temperatures, they’re both warm but one side is definitely warmer than the other

 

Maybe clamp off the hoses going to the DCCV?
That should stop all hot water going to the heater.
.
.
.

 

Sounds like you are hot on the trail.

If you need a quick band-aid, clamp off the heater return line. That will stop the flow of hot coolant through the heater core. I'm always hesitant to do this for more than a couple of hours, in case the hose takes a set. May not really be an issue, but I don't want to push my luck.

I played around with automatic reset fuses a few years ago. I was not impressed with their variability. IIRC, they could trip as low as half their rating, but this wasn't consistent. Even the manufacturer's data sheet showed this.

If the fault is electrical, try this:

1) Make sure the charging voltage is consistent after a few minutes of run time. Your late model has the smart charging system, and will show around 14.5v right after engine start. After a few minutes, it should settle around 13.7v. My early model shows around 13.7 at all times, even at idle. I don't think you should be seeing much of an increase when you rev the engine. If more than a small fraction of a volt difference, your charging system may be marginal (inadequate at idle) or the battery is on its last legs.

To determine if the DCCV or module is at fault, try jumpering battery power (use a fused test lead) and ground to the DCCV. This will command the valves closed and totally bypass the control module and auto reset fuses. If the valves stay closed now on a test drive, the fuses were at fault. If the problem continues, the DCCV is at fault.

You can also test the resistance and amp draw of the two coils in the DCCV. Details here, disassembly not required:

https://www.jaguarforums.com/forum/s...repair-251854/

The values I gave are for an early model but I think your DCCV should be similar. At the very minimum, make sure the two sides are comparable.

I'm still leaning towards a marginal DCCV that barely closes. It gets forced open due to increased coolant flow when you rev the engine. If you'd like, I can save you some time and compose your glowing response for when you realize I'm right. Again...

 

just by using the ol brute force method of touching the three heater core lines throughout the troubleshooting I am pretty sure the dccv is opening upto allow hot coolant thru the heater core when the problem arises.

the only question is why.

I have a brand new less than a year old AGM battery and ive made many voltage measurements on it with and without my iota DLS 55 supplying power.

in Fact now that I think about it - when I ran this last AC test I actually had the iota connected because I was messing with SDD at the time. So I’m sure my voltage was at least 13.8 because that’s what it outputs when you have the quick charge loop installed on the iota. And I haven’t seen any excessive high charging from my alternator.

I guess I’ll have to mess with the DCCV although I’d rather not because my big clunkin hands don’t fit anywhere near that connector so it will be painful. But I can check resistance on it and measure the voltageson the dccv connector (connected to dccv and cable end disconnected both at idle and when I rev. Its gotta be the dccv is drawing too much current and setting off my resettable fuses.

And now that I think about it the temperature in the car always felt warmer than the temp set on the climate control. And I know my AC is ice cold and the ac clutch is working as it should. Maybe ill measure the resistance on the spare DCCV coils i have in my parts car.

 

Two options to consider:

1)



2) Follow the harness up from the DCCV plug. I think there’s a disconnect near the top of the radiator shroud. You can do your electrical checks from there.

 

For some reason I was thinking the there was a connector FC4 thats I. The little side panel on the left side of the instrument panel that has those dccv wires. Ill pull out the ol schematic and verify

 

You can see FC4 near the bottom of this page:

http://jaguarclimatecontrol.com/diagnose




Image from JaguarClimateControl,com