I'm new to the forum, so hello everybody!

To start, I have a 1998 4 cylinder 4Runner (pause for applause...)

So here's the deal, I've got an error P0446 that seems to coincide with my AC blower motor not working. I've read plenty about P0446 and vacuum switching valves, vacuum leaks, and cracked charcoal canisters. I have already replaced the VSV valve and am almost certain that the P0446 also has something to do with the blower motor not working.

Here's what happened twice last month and now again: The AC blower stopped working (it was raining each time), a couple of miles on down the road, the check engine light popped on (same each time). Each time, I checked the code the next day and found error code P0446. After pulling the code and doing some research, I couldn't find anything wrong. The vacuum lines looked good, secure connections, etc. Having access to a Toyota handheld scan tool, I ran some diagnostics and out of nowhere, the AC came back to life. I promptly cleared the P0446 code and went on my way without any problems until it rained again a couple of weeks later and the process repeated with the same result as before. Today it rained again and as of now, I have a CEL on with error P0446 and no air/AC at any speed (just like the previous two times). I know I can follow the previous procedure to get by until the next time it rains, but I would really like to get to the root of the problem.

I'm pretty sure that a cracked charcoal canister would trip the P0446 code and a couple of years ago I had to patch mine up with some epoxy, so I could see that causing the code, but how does that relate to the dead blower motor/AC? Also, how does rain factor into all of this?

Before anyone asks, when working, the AC works at all speeds, so the blower motor resistor doesn't seem to come into play in this situtaion. When not working, the AC light will not illuminate and air will not blow at any speed.

I am of the opinion that there must be a correlation between the issues that I am experiencing.

Anyone else have any thoughts or possible explanations?

 

You have 2 (two) separate problems: Your AC has nothing to do with the emmissions of the vehicle. The P0446 absolutely does. Only MIL (CEL) lights have to do with emissions. The P0446 code doesn't throw when your A/C doesn't work (per FSM).
Here is straight from the FSM about your P0446 code (possible troubled areas):
Vacuum hose cracks, holed blocked, damaged or disconnected
Fuel tank cap incorrectly installed
Fuel tank cap cracked or damaged
Open or short in vapor pressure sensor circuit
Vapor pressure sensor
Open or short in VSV circuit for EVAP
VSV for EVAP
Open or short in VSV circuit for CCV
VSV for CCV
Open or short in VSV circuit for pressure switching valve
VSV for pressure switching valve
Fuel tank cracked, holed or damaged
Charcoal canister cracked, holed or damaged
Fuel tank over fill check valve cracked damaged
ECM (most likely not)
It doesn't mention anything about your dead blower motor (A/C). Which VSV did you replace? The one by the charcoal canister? Or one of them under the hood? (There are 3....)
Did you try a new gas cap (Toyota)?
I am sure that the A/C not working and the CEL (check engine light) are coincidental, and not related.

 

The VSV valve that I replaced is located on the rear of the charcoal canister closest to the firewall. I actually replaced it a couple of months ago as the old one was clicking rather loudly and the new one had an updated rubber mount intended to lessen the noise (which it did nicely).

I have not yet replaced the gas cap. More than likely I'll just get a new gas cap o-ring and see what happens there.

If memory serves, I got the message "Open or short in vapor pressure sensor circuit" as a description on the P0446.

Again, I realize that my two symptoms are part of completely different systems, but they still seem to act up at the same time. Coincidence? Maybe so... does anyone know if there is a relay for just the blower motor on the 4 cylinder 4Runner? Maybe the rain could be causing an already corroded relay to further deteriorate?

I'll get the gas cap handled in the morning, clear the code, and go from there.

Thanks for the super fast reply Stir Fry!

 

No prob. I have been dealing with P0442 and P0440 for 1 month now and had been dealing with p0446 and changed the VSV for PSV (pressure switching valve). Which changing the VSV for PSV fixed the "purge flow" code. I just ordered the fuel check valve and fuel cutoff valve with corresponding gaskets and will be dropping the fuel tank to change those hopefully this weekend. I have been through everything else with these codes per FSM, so let me know if you need any more help.
Anyway, I didn't know that your canister is in the engine bay. In my 02' 3.4L it is above the spare tire.
The stealer told me that they NEVER sell the vapor pressure sensor ($193). They have sold zero in the last 2 years. They are good parts. It is actually a VENT CONTROL malfunction or purge flow code, the P0446.
I think that the 2 things are purely a coincidence. Look under your hood for fuse / relay for your blower motor or under steering wheel. Even in the rain, it still should be dry where your fuses / relays are located.
You can not just get the o-ring for the gas cap. Just buy a gas cap from the stealer, it is worth it. $18 is what I paid. The gas cap might have cracked plastic anyway.....

 

I have an 01 and when i bought it this last october it shot me with the P0446 code 3 yes 3! days after I bought it. Took it to some friends at the Stealer and they said it was the emissions vent code and to replace the cap and go from there.. I went to the local parts house and got a generic for toyota and still same ol same. Back to the stealer I went. Same thing all over again and they asked if i had bought my cap from Yota or some parts place. For some reason they said an actual toyota cap makes a difference so I returned the other an opted for the OEM one. Seemed to help a bit...
Untill one night sitting perfectly still in a parking lot waiting on a friend to get out of work listening to my stereo here come the light after 900 some miles ( I kept it logged on my B odo) so I could get a timeline and conditions when it happened... Seemd like my loud subs had couse a pressure change and tripped the sensor... sounds odd but after some research and some common sound wave logic it coullllllld be possible for it to vibrate and contractenough to hypothetically sense a leak..... Stereo in or out for a while seemd like it didnt really matter... still came on about ever 700-900 miles or so..Soo I started running injector cleaner and fuel treatment quite frequently and seemed to help the problem.. now its more hit and miss than anything and has never effected my blower, engine, ide etc.. except it will in fact turn off my VSC and TRAC... ( which is kinda nice sometimes) since I am yet to have the grey wire mod done... So I am still at a loss for this evasive code. I have gone nearly 3k miles this time with no probs.. Knock on wood.. Luckily I have had it scanned for free every time! Our Stealer here in KY is actually a pretty stand up place I am proud to do business with... Cheaper on most all parts for the runner i have priced by at least 20 bucks. especialllly the antenna. If it werent for e may they would have had my money!

 

Hudson, You probably have a VSV that is bad. I changed one on mine and the P0446 went away. Charcoal gets in them and plugs them up so they don't switch. Most likely the one by the canister (the hardest one to replace). P0440 and P0442 are usually the gas cap (indicating a leak in the EVAP system). P0446 could also be the charcoal canister. The VSC / TRAC lights do come on every engine code thrown. That is normal. It takes about 700-900 miles for the EVAP system to set after resetting the codes, but if you have gone 3K miles since the last one you probably fixed it. But if running injector cleaner through the gas tank fixed your problem, GOOD FOR YOU!

 

It's been a couple of days, but for now it looks as if my problems are resolved. First, I followed stir_fry_boy's recommendation to pick up a new gas cap from the stealer. So far, I've put about 150 miles on the 4Runner since replacing the cap and clearing the code... so far so good.

On to the climate control issues. I went out on a limb and picked up a used climate control unit. It was only $35 and it shipped next day, so no complaints there. I promptly installed the new unit (which isn't much fun with all of the push/pull cables) but after finishing the job, my problems persisted, still now power to the unit. In a last ditch attempt to retrace all of my previous steps, I rechecked the fuses under the hood to find that there was an issue with the 40amp female fuse that feeds the blower motor. The fuse was good, but underneath, one of the male spade connectors was recessed to about half the height of its counterpart. I disconnected the battery, whipped out a set of needle nose pliers and pulled the short male spade connector up to the proper height. After reinstalling the fuse and reconnecting the battery, bam! It worked again.

Long story short, the rain didn't appear to have much of anything to do with either of my problems, or so it seems, but both problems are now (for the time being) resolved. I just wanted to post a follow up and thank everyone for their input. My wife can now drive with her AC on full blast and I can finally get back behind the wheel of my LS400.

Thanks everybody!

-Graham

 

Well, good for you! You got one problem fixed. I have my fingers crossed about the EVAP codes that you had. It does take about 800 miles for them to run and reset themselves after unhooking the battery. Good luck! You could sell one of your climate controls though.... Let me know if you need any help.