2003 Ford Explorer XLT 4.0, Clicking Noise in the Dash When Operating the HVAC System

This 2003 Ford Explorer XLT 4.0 came into the shop with a customer concern of a clicking noise in the center o,f the dash when he attempted to change the temperature from cold to hot. This vehicle has a manual HVAC control system. If he just barely moved the temperature knob, the noise would start. If he had the vehicle running and had the temp knob all the way to heat, the noise became louder.

This post is not so much a "how to", but rather a "why" post. It is not necessary to remove the entire dash to do this job; though, the service manuals call for that. I have found the job can be done by removing he center console and the cover beneath the steering column.

The issue is a common one on the Explorers around this year model. The culprit is a faulty temperature blend door actuator. Below is a picture of the actuator.

Internally, this actuator is made up of two small plastic gears. The piece that fails the majority of the time, causing this customer concern, is the smaller, black gear. If you take the actuator apart to see inside, you will see that this black gear has anywhere from two to three teeth sheered off of it. Below you will see the inside of the actuator and the black, plastic gear with the missing teeth.

Below is the small gear by itself. It may be hard to see, but in the pictures below, the two sheered teeth are at approximately the one o'clock position.

These missing teeth cause the gears to slip, not allowing the actuator to move the blend door to its proper location. When the gears hit this bare spot (the spot of the sheered off teeth) it cannot catch and so slips, causing the clicking noise in the dash.

We removed the faulty actuator and replaced it with a new OE actuator. We then tested the system, moving the temp knob from cold to warm and back several times. The noise was now gone and the blend door was operating properly.

2004 Honda Civic LX 1.7 Replacing the Cabin Air Filter

This 2004 Honda Civic LX with the 1.7 engine, came into the shop for a couple of issues.  One thing that we did while we had it was to change the cabin air filter/pollen filter. (It goes by different names depending on manufacturer.)

On this make and model, the cabin air filter is located behind the glove box. The purpose of this filter is to remove odor from the HVAC system, allowing good, fresh air to come into the passenger department.

First, access the glove box. Open the glove box. In order to get to the filter, you will need to drop the glove box down out of the way.

Below, you will see that Honda did a good job making the process much easier than it is on some other makes. You will notice the tabs on the inside of the glove box on the inside. I have my flashlight shining on these tabs.

Next, pop these tabs out and pull them out of the glove box.  The next picture shows the tab popped out of place.

Next, simply push the tab out of position and pull it out.  Below, is what the tab looks like removed.

Now that the glove box will drop down out of the way, the filter housing is easily accessible.

Next, pop the cover off the housing to access the filter.  Below, is the cover removed.

With the cover removed, you can now see the filter in the housing.  Pull the old filter out.  As you can see below, this filter was very dirty and in dire need of replacing.

In the next pic is the new filter.

Now, place it inside the housing.

Then replace the cover over the filter in the housing.

Reattach the tabs in the glove box. This can be a little tricky.  You have to make sure the glove box is partially closed, so the tabs are on the other side of the stoppers.  Once they are in place, close the glove box.

And that's it.  These filters should be changed regularly according to the maintenance schedule.  Check your make and model's info for details.  (Note: not all vehicles come equipped with a cabin air filter. There are some others that did not come installed with one from the factory, but can be added if you want one . . . a Nissan Xterra comes to mind as one of these.)

Cabin air filters should also be replaced if you are constantly getting odor out of your HVAC registers/vents. Or if your HVAC system is not blowing air out as strongly as it once did, this filter could be the cause.

2003 Chevrolet Silverado 5.3, Brake Lights Illuminated and Blower Motor is Inoperative.

This 2003 Chevrolet Silverado 5.3 came into the shop with several customer concerns.  The major concern was that the AC was inoperative.  He mentioned the AC had stopped working within the last two weeks or so and (another concern he had) his brake lights (both the ABS and red brake light) had come on at the same, or about the same time.

First things first, I confirmed the customer's concern.  With the AC on (the control panel lights were on and showing the AC was on), going down the road, cold air would blow in.  When you stopped the vehicle, no air at all.  The brake lights also were illuminated in the panel as the customer said.

Next thing, pull out a wiring schematic and do some checking on the circuit.  It was obvious from driving the vehicle down the road (and observing it visually) the AC clutch was working and the compressor was cycling.

Since the blower motor resistor was fairly easy to access, I started there.  With a test light I checked for power on the respective wires to the resistor.  The Power Probe showed no power on any wire at any speed.  The feed wire also showed no power.

(This is why it is important to "test and not guess".  I have seen a lot of people just throw a resistor in there, because they "go out all the time" only to have it not work.  Make sure you know the cause of the problem before you start removing and replacing parts.  R&R of parts can cost you a lot of time and money.  The best solution is to take it to a professional and get it done right the first time.)

Next, I went to the fuse panel in the left side of the dash.

No power at the fuses.

The brake fuse and HVAC fuse are supplied power by the ignition switch.  An orange wire supplies voltage to these fuses.  Probing this wire, as expected, I found no voltage.

It was time to replace the ignition switch.  The ignition switch is an electrical component.  It is not the part you put the key in to start the vehicle . . . that part is the key and cylinder or tumbler.  Some ignition switches will come with a wiring harness.  This one did not.

To access the switch, remove the steering covers and the tilt handle.  To remove the handle pull outward.  Sometimes a pry bar or long screwdriver may be necessary.  Just be sure not to break any of the plastic surrounding it.

The switch is located on the bottom of the steering column.  It is located just below the lock cylinder.

Disconnect the holding tabs (2 white tabs, one on each side) and gently pull down.  Next remove the wiring harness.  The switch by itself is shown from a couple of angles below.

Once the switch was replaced and installation was completed, it was time to try out the AC and see if the brake lights were now off in the dash.  Sure enough, the brake lights were no longer illuminated and the blower motor was now operational.

The high speed was inoperative, but the customer said it had been so for several years and declined to have it repaired.

2000 Chevrolet C3500 5.7, Wipers and AC Inoperative

This 2000 Chevrolet 3500 came into the shop with a couple of complaints by the customer. He said that a few days before both his AC and windshield wipers stopped operating.  He had checked a couple of fuses, but was unable to find a problem.

First things first, I confirmed the customer's concern.  The AC and the wipers were inoperable.  Next thing to do was to pull up a wiring diagram and start checking the circuit.

I first checked out the two fuses in the fuse block on the left-hand side of the dash.  The wiper and AC fuse are next to one another.  At first, I wondered if something might be going on with the terminals.  When I checked the fuses (Fuse 11 Wiper 25A and Fuse 12 HTR-AC 25A) with KOEO (Key On Engine Off) and the AC and wipers in the on position, I got ground.  No power was coming to the fuses.

Now that I knew there was no power to these two fuses, it was time to find out what their power source was.  Again, consulting the wiring diagram, I saw power was supplied to these circuits by the IGN B 50A fuse.  I saw the radio was also powered on this circuit, and when I checked the radio, as expected, it did not work either.  The IGN B 50A fuse is located in the Power Distribution Box under the hood, on the left (driver's) side of the engine compartment.

The fuse I'm pointing out is the IGN B fuse.  When I checked it with the Power Probe it showed one side with power and the other side without.  This meant we had a blown (melted) fuse.  I replaced the fuse, turned the key to KOEO and tried the problem circuits.  They all now worked.

Of course, fuses don't just blow for the fun of it.  When I reported my findings to the customer, telling him we would need to do further diagnostics to determine the cause of the blown fuse, he opted to pick it up and run it until he has any more trouble out of it.

I advised him on the potential problems and inconveniences that could result from this; but, he decided to pick the truck up as is anyway.

I just hope it doesn't decide to blow when it's raining!

2004 Nissan Altima Using Oil and Running Rough

We had a 2004 Nissan Altima come into the shop the other day.  The customer complaint was he was needing to add oil to it frequently; as much as 2 quarts every other day!  He also had a complaint for the engine running roughly.

When I checked the oil level, it was barely touching the stick.  First things first, fill it up with oil before doing any checks.  Once the oil was full (and we checked the coolant as well, it was good) we started the engine.  We noticed some oily places under the hood and inspected for any leaks.  We noticed some small leaks here and there.

Next, I went to the back of the vehicle to have a look at the exhaust pipes.  I was pretty sure, based on how much oil the customer was adding, the problem was an internal one.  I was pretty confident it was going to put out a bit of smoke, indicating a problem with the rings in the cylinders.

I had asked the customer if he had noticed any smoke.  He said he had seen some, but really wasn't sure.
We revved the RPM a bit and as we did smoke started coming from the pipes.  It may be hard to see, but the smoke is visible in the picture below (whitish/grayish in color).

 The more we increased the RPM, the more the smoke boiled out.

When we snapped the throttle to red line, WOT (Wide Open Throttle) the smoke thickened even more (my camera wasn't quick enough to capture it) and oil spit out from the exhaust pipes.

The black specs on the floor in the picture above is oil from the pipes.  Below, I got some of the discharged oil on my finger to show.

Long story short, this vehicle is in need of an overhaul or engine replacement.

2002 Chevrolet Cavalier 2.2, Engine Light on with a P0440 Code Stored

This 2002 Chevrolet Cavalier 2.2 came into the shop with a DTC P0440 Evap Emissions System Fault.  The first thing we did was to give a visual inspection of the EVAP system.

We did not see any obvious problems, such as, broken or disconnected hoses, unplugged components (i.e. purge or vent solenoid), broken wires, or loose/missing gas cap.

Many people, when presented with this code, will automatically replace the gas cap.  While these caps do need replacing from time to time for maintenance issues, this may not solve the problem.  In this case, the gas cap was not the issue.

We then decided to use our diagnostic tool and, using its bi-directional command capability, commanded the purge and vent solenoids on and off.  When we did, we heard (and could feel) each one turning on and off as we commanded it.  We did this several times to ensure there was not an intermittent problem with sticking in the solenoid.

Next, we connected our smoke machine, which we use to check for EVAP leaks.  Again, using the diagnostic tool, we commanded the vent solenoid on (which closes the valve . . . this valve is normally off and thus open, to do the test it must be "On", meaning the vent is closed, so as to allow the system to hold the smoke in), and tested the system with smoke.

The picture below shows the evidence.  It is a bit hard to see, so we have drawn an arrow to point to the evidence.  What we saw was smoke boiling out of the vent solenoid, even though we were commanding it "On", thus closing the vent.  Therefore, with the vent "On" no smoke should have been escaping.

With this evidence, we removed the vent solenoid.  What we found is that someone had tie-strapped the diaphragm.  More than likely, a previous owner (our customer said they had not done this) knew about the problem and tried to rig it to work.  Not a good idea.  The solenoid was actually leaking from around its diaphragm, so a new one was in order.  A picture of the old one, tie-strap still on is below.

The next picture shows the new vent solenoid in place.

  
Just FYI, there is a short wiring harness (see below) connected to the vent solenoid.  These are notorious for fraying and breaking, due to rear end movement.  Like the gas cap above, this was not the cause of this failure.  Silver bullet fixes usually end up costing a customer far more money than simply taking it in to a professional to have it properly diagnosed and repaired.

Here is the short wiring harness (I am pointing to it in the picture).

After completing the repair, we cleared the codes and data associated with it.  We then ran a EVAP system test with our smoke machine.  The test passed.  A picture of that is below.  You will notice the green lit LED indicating the test completed and passed.

There are many variables when it comes to diagnosing and repairing an EVAP system.  A basic understanding of how the EVAP system works on that particular make and model is essential.  A visual inspection is always the first place to start.

Don't jump at silver bullet fixes.  You may get lucky and it may be your problem and repair your vehicle.  Then again, you may spend quite a bit of money chasing several silver bullets and in the end be left with the original problem.

When in doubt, find a professional you can trust and take it to him/her and let them do the proper diagnostics and repairs.  It may end up saving you far more money in the long run.

I know the economy has been rough and times are tough.  But, throwing parts at a problem can compound that problem quickly.

2005 Ford F150 King Ranch Edition 5.4 Misfire

This vehicle came into the shop with a customer complaint of a rough running engine, a misfire.  Customer said he was driving along on a trip and all of a sudden the truck started to misfire and run poorly.

First things first, we verified the customer's complaint.  Took the truck for a test drive and confirmed the misfire.  Next, we connected our diagnostic tool and checked for stored codes.

We pulled three DTC's.  They were P0171 System Too Lean (Bank 1); P0303 Cylinder 3 Misfire Detected; P0316 Engine Misfire Detected on Startup; and P0353 Ignition Coil C Primary/Secondary Circuit Fault.  We checked the freeze frame data and started our diagnostic.

We weren't concerned with the first code, with an active misfire on that bank, the lean code is explainable.  We needed to know what was causing the misfire.  Just a head up, on the last code P0353, the Ignition Coil C . . . C is number 3 cylinder.  Ford uses letters to correspond to the cylinders.  So "A" is 1, "B" is 2, "C" is 3 . . . "H" would be cylinder 8.  Okay, you get the idea.

Another FYI for you, Ford commonly mistakes cylinders.  So it may throw a cylinder 3 misfire, but when you start investigating you determine it isn't number 3 that actually has the misfire.  So be careful with that too.

Now, we needed to see what was causing this misfire.  Was it a plug, coil, wiring, or PCM?  With the P0353 code, any of these could be possible.

So, we hooked up our lab scope and sync probe and did some investigating.  First, let's rule out the PCM and wiring.

We checked battery voltage at the PCM with key off and with at KOEO, both showed good.  So wiring seems to be fine.  What about the driver in the PCM?

That's where our lab scope and amp probe come into play.  The picture below shows two traces (one red and one green).  The red trace is through the amp probe connected around the power feed.  This wire was accessible in the steering column and was fairly easy to get to.  It is a dark blue wire with light green tracer.  The green trace is our sync probe, allowing us to know which cylinders are which.  In this case, we were connected to number one cylinder.  With that info we could go by the firing order if we saw any problems in the patterns.  Here, what matters, is that all 8 cylinders are accounted for.  You will notice there are 8 red "lines" between each green "line".  This would suggest the PCM is onboard and functioning.

Now, we need a closer look to see where the problem lies.  The below pic shows a zoomed in view of the above pic.  Notice the difference in appearance of the two sets (3 spikes each) of red traces.  The first is nice and pointed, the second image (to the right) sort of curves over to a point and then drops straight down and then straight back up.  The first one is a known good pattern.  The second is a view of a shorted secondary ignition component: either plug or coil.  I know these trucks and engines are known for bad coils, but you have to follow the evidence to make a proper diagnosis and the right repair.

The next pic is an even more zoomed in look at the known good pattern.

The pic below is the faulty pattern . . . again, notice the differences between these last two images.

As I said earlier, these vehicles are known to mis-identify the offending cylinder.  So, we moved our sync probe from cylinder number 1 coil (control wire) to cylinder 3 coil (control wire), the cylinder that is supposedly the misfiring cylinder.  Below is the pic of this.

Based on the above pic, we knew it was indeed cylinder 3 that was the misfiring cylinder.  So, in this case, the PCM had the right cylinder pegged all along.  Now it was a case of determining if it was the spark plug or the coil that had shorted.

It turned out to be the spark plug.  The plugs had been replaced about a year ago.  So, we removed that one plug and replaced it with a new one.  We also ended up replacing another coil because it showed signs on the scope of weakness.

Started the truck and it ran like new.  Took it for a test drive, allowed the monitors to run, double checked no misfires being reported, lean situation straightened out with the misfire no longer present, cleared the codes, and shipped the truck.