so I just picked up a 2001 s type this morning. It has 79k miles for 1,100. He told me when I brought it that the fan control module is bad. I drove it home today and everything works great besides no heat out of vents and inside cabin fan stays %100 cold air. The car temp stays in the middle doesn't look to overheat. Where should I start with this one

 

Welcome to the forum Mike,

I've moved your thread to the S Type tech section for a better response.
Don't forget to post an intro in the new members section when you have time.
What engine do you have?
A forum search is your friend with this one, the dual coolant control valve, DCCV, is the chief suspect but there are other possibilities and many threads, the temp gauge is an "idiot" gauge and will not head for the red until it is almost too late.

 

Hello, and welcome to the forum. Congrats on your purchase.

For the no heat, first check your coolant level at the reservoir. On my '02 V6, if the coolant is low, the heater runs cold, especially at idle. V8 models have an auxiliary coolant pump to help with heat output at idle.

Next, manually select the temp to HI. Use the up/down button on the climate control panel. Bump up the desired temp until the display shows HI. This bypasses most features of the automatic system and puts it in manual mode. This helps rule out several components.

If still no heat, check the temperature of the coolant lines with the engine warmed up and turned off. The heater core is centered behind the middle of the firewall. You should see three metal lines running from there forward on the (US) passenger's side of the engine compartment. At the front of these three lines is an octopus-looking Dual Climate Control Valve ( DCCV). Compare the lines feeding the DCCV with the lines running aft to the heater. If the supply side is warm but the heater side is not, the two solenoids inside the DCCV are closed and not letting hot coolant reach the heater.

The DCCV is very prone to failure. The solenoids are spring-loaded open so you will theoretically still have heat (for the defroster) for safety with an electrical failure. Before rushing out to change it, run a quick check to see if the valve itself has failed or if it's not getting a signal to open. Disconnect the electrical connector. This relaxes the spring-loaded solenoids and should give you max heat. If still no heat, and the supply lines are hot, the solenoids are stuck shut. This is a very common issue, so don't be alarmed.

Run these simple checks and let us know what you find.

For the temp gauge, read some details at this link. Basically, with coolant temp anywhere from approximately 180 to 230, the needle stays centered. It's a bit misleading:

https://www.jaguarforums.com/forum/s...tation-152099/

I'm also curious about the suspect fan control module. It's on the backside of the radiator shroud, down low on the (US) driver's side. Does the fan run at all? I'm not sure what conditions are required for the fan to run. I think if the AC compressor is commanded on, the fan will at least run at low speed, possibly higher. If the fan never runs, you may not notice it during cold winter weather, so definitely investigate that before warm weather returns and the engine overheats. If the fan never runs, I'd suspect the fan motor itself first. Details of my experience here:

https://www.jaguarforums.com/forum/s...-gauge-159542/

 

Didn't have much time this morning but I noticed the coolant was about 1/2 quart low. Filled that up, let it idle for about 10 min. Turned the bleed screw and a very small amount of air came out. Still very little heat.

I had had also had the fan on high for those 10 min. I checked the 3 lines, the bottom two were hot and the top one was warm. Hard to see down there but does that mean the valve is closed shut and not letting the return line flow.

If that fixes the no heat issue, will that also fix the issue with the fan always running when the car is on?

 

The radiator fan constantly running is indicative of a stuck or sticking thermostat combined with low coolant level.

There is also a bleed screw for the heater core located next to the coolant expansion tank. With the screw loosened, a small amount of coolant should drip out, if not, air is trapped inside the heater core.

When time permits, perform the check of the DCCV as recommended earlier as they are prone to a high rate of failure.

 

I just had an uff da moment. You are talking about the radiator fan, right? After rereading this thread from the beginning, I had some doubts and wondered if you were talking about the heater/AC fan (inside the cabin) instead.

As far as the radiator fan, make sure the system is properly bled of air. I've already mentioned my preference for the unapproved drive & refill method. If using that method, running at idle won't do it. Either follow the official bleed procedure or drive the car hard for a day or two to clear all the air.

 

 

 

I checked the radiator fan with a/c on and also off with the car warm. The fan seems to be on low, but running. I also unplugged the dccv then plugged back in. Still no heat. The bottom two lines from the heater core r to hot to touch. The top one u can hold your hand on it. The problem I'm having is the in cabin fan runs full speed and it won't put out any heat. When I brought the car the guy told me it had a bad fan module. That's what his tech told him. Told him it would cost over 1,300 to fix.

I also got paperwork with the car showing the water pump and thermostat were replaced 15k ago

 

 

I would still go through the checks mentioned above. Leave the DCCV plug disconnected. Hopefully the thermostat was installed correctly with the check valve installed at the 12 o'clock position.

Your heater core could be possibly blocked or more than likely one of the solenoids in the DCCV is stuck closed not allowing coolant to flow to the cabin on that side.

You have hot coolant going to the cabin on one side of the car by the hot hose.

If you think the fan module is the culprit I have one available but based on your description the fan is operating normally.

Finally, open up the port next to the master cylinder and ensure you get a stream of coolant...

Good Luck

 

Glad I asked which fan was acting up. Your radiator fan operation seems fine. Please ignore my comments about the fan in post #3. I thought you were talking about the radiator fan.

Okay, some progress there. It's still possible the DCCV innards are stuck closed, even though they are spring-loaded open.

I hope I haven't misled you by having you check the temperature of these lines. I remember playing around with this on my car, and it was tough to discern the coolant temp inside the lines because of the close proximity to the exhaust manifold. So let's just consider those results inconclusive for now. Had the lines been cold, that would have pointed to a DCCV problem.

The heater core has two halves, each fed by one of the smaller lines. (This lets the driver and front passenger select different temperatures.) The larger line is a common return line.

Normal operation, if full heat was commanded on both sides, is the two smaller lines would be hot. As fan air travels over the heater core, that heat energy is extracted and the common return would be cooler than the two inputs, although still warm. Alas, like I said, the close proximity of the exhaust manifold makes this hard to tell this temperature difference.

$1300 sounds pretty darn high.

Before we get too carried away, please be aware how the cabin fan is supposed to operate. On a cold day, with the coolant still cold, the fan only runs at a very low speed when in AUTO mode. The logic is not to blast you with cold air until the coolant is warm enough to provide heat.

Please confirm the fan behaves like this with AUTO selected on the panel.

If, on the other hand, the fan always runs at full blast in AUTO even when the engine is cold, then that's a strange one.

Also, please understand the computer brain for the climate control is very smart but also very stupid, all at the same time. If still in AUTO, and a warm temp is selected, the fan should run very slowly at first until the coolant is warm, as previously mentioned. Once the system thinks heat is available at the heater core, the fan speed will increase.

This is where the stupid sets in. If you're only getting cold air from the heater core (several possible reasons), the duct output temperature is not monitored. The cabin temp is monitored, but not the heater ducts themselves. The computer might see the cabin temp is still cold, and full heat has already been commanded to the DCCV (hopefully routing hot coolant to both sides of the heater core, but also not monitored). With full heat commanded but no increase in cabin temp, the computer responds with the only trick it has left: to increase the cabin fan speed. In theory, this will blow more heat into the cabin, but not if the heater core is cold. Very smart and very stupid, all at the same time. You get lots of cold airflow.

So when you mentioned the cabin full running at full speed all the time with no heat, that's the common scenario I imagine. If the cabin fans runs at full speed even with the engine cold, then I'm all wet.

Very important: have you tried running the climate control system in manual mode? To do this, bump up the temp setting until HI is displayed on the panel. This bypasses several sensors and disables some of the logic. It also puts the fan in high speed mode, but the fan speed can be manually controlled by its own up/down switch on the panel. It's great for troubleshooting.

Also, is your car V6 or V8? The V8 has an aux coolant pump to help with heat at idle.

To recap, please answer these questions. Yeah, I know, I'm a bit wordy. I want to make sure these important answers don't get lost in my novel above:

1) In AUTO mode, does the cabin fan run at full speed even when the engine is cold?

2) Can you manually control the cabin fan speed using the fan speed switch on the panel?

3) V6 or V8?

 

I noticed when I put it on auto it will kick the sound of the fan down. I also checked the aux coolant fan and when the car is off there's no power to the plug, with the car on it has power and I can feel the motor running.

If I turn the fan speed manual it turns the speed down but I can still hear the fan going sounds like on the pass side.

The car is a v8

I removed the glove box and there's a red and black plug and when I unplug it the fan turns off all together.

With the glove box removed I can see the heater core lines. The bottom one is to hot to touch. The top two are warm if that. From that it tells me the hccv is not working right, because all 3 lines should be hot. I also unplugged the hccv and it was the same.

 

I pulled the dccv and I guess I'll just be waiting on parts To come in. I think I neeed to solve the no heat issue before I work on why the fan using Turing off

 

All right, making some progress.

Let's not worry about anything in auto mode for right now. Let's keep all troubleshooting in manual mode until we get a handle on this. Also, keep the DCCV unplugged, so the valves will hopefully spring full open as designed and give max heat. Try gently percussing the valve body on each side and see if that helps free them. Don't tap the aluminum solenoid bodies because if you dent them, they may jam.

From your description, it sounds like your cabin fan is working just fine. I'm a little perplexed by the previous diagnosis of needing a "fan module". Even in manual mode, with the fan at its lowest speed setting, it still turns slowly. With the engine running, the only way to shut the cabin fan off completely is to select OFF on the climate control panel. If there's a problem with auto mode, let's ignore that for now. Since your fan seems to be operating (even if not perfectly), it's spinning and should be pushing air through the heater core. Let's concentrate on why there's no heat, and not worry about the fan at all for now. Whether it behaves properly in auto is another question, but only crisis at a time, please...

Can you please confirm the operation of the various doors in the climate control system? Kind of a long shot, but I'm wondering if your heater core is plenty warm, but the discharge air is not being routed properly. With the engine running and the fan speed on high, use the buttons across the bottom of the panel to manually select where the air is discharged. I'm not concerned with the temperature so much right now, just where the air goes. With defroster selected, you should have full air flow to the windshield. Select the footwell icon and all the air should be directed underneath the dash. (There may be a small percent routed to the defroster ducts at all times, not sure) Select the vent icon and all the air should be directed out of the face of the dash.

Also, please confirm the airflow is good and strong out of the various ducts. One possibility is debris such as a plastic bag across the face of the heater core. Something like that could cause all sorts of grief.

If the door operation and airflow quantity checks good, select the A/C switch to the off position. The light below the switch should go out. I want the switch off just in case there's some funky signal causing the A/C system to put out max cooling. On a winter's day, the A/C loafs along to dry the cabin air and limit fogging inside the windows. The compressor should only cycle on every few minutes for a short burst. It doesn't take much run time during cool weather. By selecting the A/C off, we can make sure there isn't lots of cold air inadvertently being mixed with the heater output. Look under the hood at the face of the compressor pulley with the engine running. The face of the pulley should be stationary with the switch off. Double check that just in case the control panel is fried and commanding max A/C even with the switch off.

I took some temp readings with an infrared thermometer on my '02 V6 this afternoon, after a 25 mile drive. All readings taken with the engine at idle, climate control in manual mode HI, and max fan speed. Ambient air temp was 40 degrees. The coolant measured approximately 200 degrees at the inlet to the radiator.

The temp readings on the metal heater lines were taken near the front of the engine, as close as possible to the DCCV. With HI heat commanded, the two smaller lines (top and middle) each measured approximately 195 degrees. The larger return line at the bottom measured approximately 150 degrees. Discharge air temp from the center duct was approximately 110 degrees.

Also, is your car currently driveable? I noticed you had it delivered on a flatbed. If not driveable, why? On my car, the heater really doesn't kick in full strength until I've driven at least ten miles. If you're doing all your troubleshooting at idle in the driveway, that may be making the problem seem worse than it really is. I can't stress this strongly enough, you need to work the engine to get the heater to wake up, at least in my limited experience.

Now if everything above checks normal, based on your temp readings, it sounds like at least one side of the DCCV is not opening fully. Both of the two smaller lines should be hot, not just one. If pressed for a best course of action, I'd suggest replacing the DCCV. I'm very hesitant to say "replace this particular part" but if ALL the above checks pass, then the DCCV is your most likely culprit.

The other possibility, and much less likely, is a clogged heater core. An internal blockage would prevent coolant flow through the lines, and give the low temp you observed on the lines.

I'd still lean towards the DCCV, just because they are a high failure item. While you have it out, you can reverse flush the heater core. Connect a garden hose to the large return line. With the other two lines disconnected, you should get approximately equal flow from both sides. If one line has significantly less flow than the other, that would indicate internal blockage. With any luck, the reverse flush will clear any blockage. The heater core is a booger to change. I certainly wouldn't try it until after replacing the DCCV.

Our own Gus has posted a nice how-to on replacing the DCCV:

JagRepair.com - Jaguar Repair Information Resource


Anybody else got any thoughts on the matter?

 

First, beautiful car!

Second - I fully agree with KR98664's advice and guidance - sounds like your DCCV is done.

I fully believe once you swap the DCCV and bleed out your cooling system you should be set and toasty...

Third - spend the few extra dollars and order a Motorcraft DCCV (Part # YG-355) it's around $150 on Amazon - don't worry about compatibility it will fit! You will find many parts for the Lincoln LS (2000 - 2002) will fit our S Types.

Many of the cheaper knock off DCCV's (sub $100 - they're out there like Metrix) are mostly bad out of the box. I purchased one that only lasted 2 months before both solenoids were stuck in the closed position. I learned the hard way on a sub 40 degree evening with no heat!

I purchased the Motorcraft DCCV and I am glad I did as rest assured I will never, ever be changing out my DCCV ever again!

While you have the DCCV out change whatever hoses you can. Also, remember, when swapping hoses over to the new DCCV make sure you line up the line on the hose to the marked line on the DCCV to assure proper hose routing. Also, install the 2 rubber o rings and white nylon ring between both for the connector to the metal cooling lines and lube them up with coolant and ensure the plastic tabs fully click into the plastic hoses and pull the hose slightly to ensure proper locking.

The return hose connection is much easier.

Thanks and agreed your making great progress... If you pop off the top two hoses and put a light into each you will find either one or both solenoids stuck closed. I still have to pull mine apart to inspect further for kicks so I can report back but clearly I had both solenoids stuck almost 100% shut giving me no coolant output to the heater core after shining a light into both hoses.

 

Well, I guess I overanalyzed the daylights out of that one. At least we both came to the same conclusion. Fingers crossed, keep us posted.

 

Pulled the hoses off. Is that open or closed.
Don't know much about these, but that's open right? I should be getting heat though the lines?

 

I'll look at mine but I think they're stuck closed...

 

I'd say you found at least part of the problem. The two valves should be spring-loaded fully open.

Seems like that should have given some heat, but who knows.

Just to be safe, did you back flush the heater core?