How bad is P0538 code?

[Slow Car Sport Mode]

I'm having trouble getting good information about this. P0538 disables the air conditioning (this example is related to a 2004 Ford Taurus, Vulcan) I knew it was something like that when compressor could be manually engaged and changing $10 solenoid did nothing. Turns out P0538 is a "Thermistor" and there is surprisingly little info about this problem I have been able to find.

Research seems to indicate repair difficulty 3/3 (hardest it can be) or requiring removal of the windshield for a "shortcut." Something along the lines of "entire dash has to be disassembled to get to."

Well beyond my skill set. Truly bothersome when it is very hot outside. Good thing the AC works on mine...

So, I thought I would make a thread to ask just how tedious/PITA a P0538 code is, and if any here that work on cars have had to deal with this code. (It was always showing up for about a year but I never fully knew its relevance until it got hot out. I thought the AC was working for a long time and it was not.)

 

[Dave9]

Does seem tedious, taking dash out to get to the sensor. Might be easier if you can find a youtube video for the specific/generation of vehicle, but still a lot of time due to sensor placement.

One alternative might be determining where the wires to this sensor originate from, and determining if you can just cut those and wire up a new sensor, located elsewhere? It would help to know more about how this sensor reading impacts the HVAC system, how critical its placement is.

If it's just a thermistor and you can figure out the specs for it, might even be able to use a (discrete electronic component) regular off the shelf thermistor, lowering cost, reducing space to place it in, not needing a connector but instead soldered or crimped into the circuit.

Since you don't have a working example, if you can't find data elsewhere, I'd wonder if you could find an auto parts store with a compatible part and use a multimeter to measure its resistance at ambient temp, and after holding it in your hand to raise it to 98F temp. That should give you some idea if not a perfect match.

 

[Slow Car Sport Mode]

Does seem tedious, taking dash out to get to the sensor. Might be easier if you can find a youtube video for the specific/generation of vehicle, but still a lot of time due to sensor placement.

One alternative might be determining where the wires to this sensor originate from, and determining if you can just cut those and wire up a new sensor, located elsewhere? It would help to know more about how this sensor reading impacts the HVAC system, how critical its placement is.

Well, that's more what I thought lol. I honestly thought P0538 was a "AC system outside of preset values" code (system pressures?) and spent a lot of time measuring that all the levels were correct.. when I saw the compressor not coming on when commanded on, I did the paperclip test, went from there, and then when I did some in-depth diving on the ONE YouTube video I saw and also other info (it's a "thermistor" and it's pretty much right in the middle of the entire dashboard like a heater core just harder) I said.. Oh yeah, this car is getting sold if I ever get it.

I don't handle the heat well.

I did see one video mention "take the windshield off, get to sensor with long nose pliers and minimal removal, replace, done" - but then you're re-sealing a windshield and though I've never had a problem the couple of times I've had to get a new windshield.. apparently not everyone is as good as re-sealing. My mechanic has a yellow A4 and his windshield now leaks water. My guess is that whoever put it on didn't do so very well so.. that means I'd avoid them......

*This is is why I might sell the car if the repair bill is too high* it's the principal of not having AC. Gotta wonder. Ford apparently puts it right up against the firewall in the vent in perhaps the hardest to reach location. No attempt to make it accessible.. question could be asked if that is even possible. Still not 100% sure where it is. So this may be a unique horrendous Ford design and it may not....

@ripcord How's that work?

@michaelluscher Oh it has one. 2004

 

[ripcord]

Right angle drill and a hole saw blade?

 

[Astro14]

How bad is it?

The AC doesn’t work.

The thermistor is a common AC part. A thermistor is a resistor that varies resistance with temperature. In this case, it measures evap temperature. They’re very thin wire and can break pretty easily. I’ve done a thermistor on many of my cars.

Some cars are easy to change (e.g. Volvo, 20 minutes if it’s your first time, 10 if you’ve done it before.) and some are not.

It has to sit next to the evaporator in order to work correctly, so, depending on how the car is built, that can be hard to get to.

If you want the AC to work, then you’ve got to replace this part.

 

[michaelluscher]

I didn't even know the Gen 4 Taurus had an EVAP temp sensor (to prevent EVAP freeze up)
Mine didn't
They eliminated it in late 2005

Read more at: https://www.obd-codes.com/forums/viewtopic.php?t=19159
XW4Z-19C734-BA

When I get home, I'll dig into my Ford service manual CD, you're best bet might be to cut the wires and add a resistor to force the system on

I'll post info I find later

You can have the dash out of a Taurus/Sable in 45 minutes or so
Once we ascertain where the temp sensor is on the HVAC case, you can establish a game plan
Remember, the ICP/Radio, glove box, and defrost grille all pop off pretty easily, so you might be able to sneak in

 

[michaelluscher]

FORScan should be able to give you live data of the temperature the EVAP temp sensor is giving

 

[SC Maintenance]

Based on its location I would guess its simply trying to verify a temperature drop across the condensor coil to make sure its not frozen up. Is there a schematic showing where in the plenum the sensor actually is?

If you could figure out if it was actually really a thermistor - maybe its a standard industrial one like 3K ohm, 10K ohm, 20K ohm or whatever, and you could rig something up in the discharge area to fool it enough to turn on - without pulling the windshield?

 

[atikovi]

What part of the country are you in and how much do you need a/c? Can't you just drive another of your cars on the hot days? Unless you can DIY the repair, are you going to spend over $1000 to fix a comfort item on a 20 year old car?

 

[TomYoung]

What part of the country are you in and how much do you need a/c? Can't you just drive another of your cars on the hot days? Unless you can DIY the repair, are you going to spend over $1000 to fix a comfort item on a 20 year old car?

That's not the bitog way of looking at this. The car is a 138K Taurus that I would bet is still delivering excellent service. I agree that a $1,000 repair bill is a tough pill to swallow, but was all about the workarounds suggested above. (Right angled drills, relocating the component etc.) Air conditioning is maybe not quite an accessory in the US Mainland, but pretty close.

 

[atikovi]

The BITOG way of looking at it is if the cost of repairs exceeds the value of the car, just live with it and put the money you would have spent on the repairs in the bank to save up for a replacement car.

 

[dumkid]

The BITOG way of looking at it is if the cost of repairs exceeds the value of the car, just live with it and put the money you would have spent on the repairs in the bank to save up for a replacement car.

I thought it was if the cost of repair exceeded the cost of a well maintained replacement car

 

[atikovi]

I thought it was if the cost of repair exceeded the cost of a well maintained replacement car

Sure if the repair is to keep the car driveable or safe, but this is about A/C. Nobody (except for medical reasons) NEEDS a/c.

 

[dumkid]

Sure if the repair is to keep the car driveable or safe, but this is about A/C. Nobody (except for medical reasons) NEEDS a/c.

That's true, people live without it. I'm not one of those people. 110 degrees outside temperature is bad enough in the shade, I don't like being in a metal box at that temperature even if there is a breeze.

 

[Audiman]

What’s a well maintained car? I’ve got a “well maintained car” that has had thousands spent on it throughout its life but that doesn’t mean it doesn’t need any repairs doing now.

In my opinion, especially if you can do the work yourself, you are better off keeping a car as long as it’s rust free and it doesn’t have an ever increasing amount of repair costs.

If the only repair it needs is a AC sensor. Keep it and fix it.

 

[michaelluscher]

Pop the glovebox down/out, you should be able to see it
In this hole

Report back on what you find
Also consider if it's had a cabin air filter lately, might wanna pick one up

The video you probably saw was of a CD3 Fusion/Milan/MKZ, or the later D3 Taurus/MKS

FORScan for Android is also available

Download FORScan

 

[supton]

Sure if the repair is to keep the car driveable or safe, but this is about A/C. Nobody (except for medical reasons) NEEDS a/c.

I dunno. maybe not need but I have put defrost mode to good use on rainy and stupid humid days a number of times. So I sure would want it, but would admit it’s necessary only a few days of the year (like all of last month up here!).

Really sunny days it can be nice too.

 

[Dave9]

The BITOG way of looking at it is if the cost of repairs exceeds the value of the car, just live with it and put the money you would have spent on the repairs in the bank to save up for a replacement car.

I have to strongly disagree with this, but not with you, just what I recognize you stated, the BITOG way...

Here at BITOG, many of us over-maintain our vehicles and they are worth more to us than the book value, so quite often it makes sense to spend a bit more on repairs, because we know the rest of the vehicle, or at least a lot of it, is sound for a lot more miles.

It's very seldom cost effective to buy a replacement vehicle unless it needs major engine or tranny work. $1K? No, just swapping vehicles and fixing the replacement up the same as you had yours would not be worth the bother.

Granted, it's hard to have a crystal ball that can predict when a texting teenager will run into you, and it weighs against whether to have comprehensive insurance coverage on something depreciated below a certain value.

I would easily pay $1K to fix the devil I know, than to gamble on the one I don't with a replacement vehicle... as long as it doesn't have other obvious, killer problems putting it one foot in the grave.

Put in perspective, if you DIY repairs, putting the money saved into the bank, won't amount to enough to replace a vehicle any year soon if it's just $1K as if that's a new event rather than a regular occurrence.

Some people are annoyed by nickel and dime repairs. Me too, but in a cost analysis, it is seldom beneficial to withold repairs to save that little bit of money towards a different (presumably newer) vehicle if you are DIY the labor on the repair.

IMO, fix what you feel you need to. Don't let someone else tell you that you don't need A/C if that is important to you. Life is too short to listen to people who want to micro-manage your life instead of likewise listening to what you are telling them. IF A/C wasn't worth the bother, you wouldn't have mentioned it.

It's crazy to me that people try to pretend that you have to sacrifice something like A/C or whatever, that it's somehow forced upon you not to keep an older vehicle perfectly working...and in doing so, you still save several thousand dollars. NO! It's sad that people want to project that you have to give up anything important to drive an aging vehicle when the truth is, all you really have to give up is the newer babysitter tech, and of course, some fuel economy but the tech to achieve that, comes at a long term cost as well.

All the above does not mean someone should pour money into something at end of life. Consider the mileage, consider the frame/unibody rust rot, and all other wear factors relevant to the specific vehicle. In this case it's just a sensor. I have an abbreviation for how I feel about that but am not allowed to post it, lol.

 

[Junk]

Pop the glovebox down/out, you should be able to see it
In this hole
View attachment 166173
Report back on what you find
Also consider if it's had a cabin air filter lately, might wanna pick one up

The video you probably saw was of a CD3 Fusion/Milan/MKZ, or the later D3 Taurus/MKS

FORScan for Android is also available

Download FORScan

I second this, looked it up in the service manual and it says the same thing, behind the glove box. The processor strategy on these cars uses the evaporator discharge temp to determine whether or not the a/c clutch should be engaged, and if the temp is out of spec it disables it.

 

[Nick1994]

Pop the glovebox down/out, you should be able to see it
In this hole
View attachment 166173
Report back on what you find
Also consider if it's had a cabin air filter lately, might wanna pick one up

The video you probably saw was of a CD3 Fusion/Milan/MKZ, or the later D3 Taurus/MKS

FORScan for Android is also available

Download FORScan

Could someone cut a hole in that box, reach in and replace the part, then glue the plastic piece that was cut off back on?