Well, if the AC compressor clutch is pulling in, and the blower is moving air, I suspect you are out of Freon (or whatever they call the cooling juice right now). There are several pressure switches and other fun things in the line, but they all drop the clutch out. Are you sure the clutch is pulling in and staying in?

The other possibility is that the air mix servo (damper control) is not working. Is the air blowing out the dash vents just fine?

Interesting, the compressor drops out above 2k rpm.... did not know that.

 

Interesting, the compressor drops out above 2k rpm.... did not know that.

I'm reviving this thread a little since the OP's problem was fixed and this statement by RTFM piqued my interest. At the time, I looked through all the AC sections in the FSM and couldn't find this. Can you point me to the correct section it's in?

I thought this odd at the time. That means anytime you're doing 65 or 70 mph on the freeway (uphills around here anyway), then the AC would never work because the RPMs are never at/below 2K. And it means it wouldn't have worked going up I5 in past years with the high speed limits. So I didn't think this was true.

But then I had a problem on Friday. Heading down the hill on the freeway, I decided to turn the AC on. I could feel the compressor kicking in, but no cold air (hope it wasn't the air mix door!). Tried many times with no luck. Then I got stuck in traffic down in town (15 minutes later) and thought about this thread again. So I tried it again. And cold air started coming in. No problems since then even on the freeway.

So is the compressor really supposed to drop out above 2K? And now I'm also hoping it was a fluke with the air mix door/motor. No flashing lights on the dash and everything was really cold when it was working while in traffic and later on the freeway.

 

Interesting mod. Not sure I think it's a good idea, but it's your vehicle.

Is there any chance you have missed any of the wiring when returning it to stock? (I'm sure you checked like 3 times, but have to start somewhere, right?)

 

I didn't miss any wires, all the mod consists of is unplugging the green wire on the fan position servo and splicing it into the pink one next to it, only 2 wires so I've got it back to stock.

 

Ok so I just went through and double checked all the fuses and wires, everything was fine. I also checked the AC relays under the hood, they too checked out fine.

I also confirmed that all the servo motors are working properly. And the fan clutch is indeed engaging when I turn the system on and off.

EDIT: Just messed with it some more, the pipe from the condenser is getting cool but not very cold.

 

Sound like short on coolant to me if the pipe isn't cold

Do you mean compressor clutch, not fan clutch?

 

Yeah I meant compressor clutch. It seems like low coolant to me too but the thing is it literally worked Tuesday icy cold and didn't work Wednesday. If it were leaking coolant I would have noticed it getting warmer and warmer over time, wouldn't I? I didn't hit anything that could have punctured anything and caused a big fast leak.

And the pipe does get cool, just not super icy cold.

 

It seems like low coolant to me too but the thing is it literally worked Tuesday icy cold and didn't work Wednesday. If it were leaking coolant I would have noticed it getting warmer and warmer over time, wouldn't I?....

And the pipe does get cool, just not super icy cold.

Don't know about the rate of leak, unless it was huge. The FSM doesn't give any clues on the temp of the pipe. They do everything with the pressure in the system.

 

The A/C is needed to actually stop the windows from fogging so I do not understand why you would want it not to come on in the defrost mode? I have checked my gas mileage running the A/C through a complete tank full and no A/C same route everyday same driving pattern and no difference.

 

Because I live in the mountains where there is almost no humidity in the winter. You need to defrost (apply heat) not defog. But thats not the point, I'm trying to fix my AC I already feel like an idiot for screwing it up so you don't have to rub salt in the wound.

 

Was not trying to make you feel worse. Sorry If it came through that way. But I still dont understand why you would need to stop the compressor from coming on when defrosting? Try disconnecting the Battery and see if it resets something.

 

The whole point is just to be able to control it manually, I just didn't like the thought of the compressor running for no reason all winter. If I need the AC to dehumidify the air with the mod you just push the AC button to turn it on.

I already tried unhooking the battery and resetting the computer this afternoon, didn't do anything.

 

If everything was functioning as it should prior to the mod, then it's a bit silly to be looking at things unrelated to the mod.

As far as the mod itself goes, I believe modern systems have built-in overrides that disable the AC drying effect when the outside temperature is appreciably below freezing.

 

As far as the mod itself goes, I believe modern systems have built-in overrides that disable the AC drying effect when the outside temperature is appreciably below freezing.

I don't know about that. I use my defrost on dewy mornings when it is definitely above freezing, and get the infamous A/C "lurch" while at stop signs if not using enough brake pressure.

So I would say the above does not apply, at least to the 2006 model year.

Geoff

EDIT: sorry, just re-read your post more carefully; didn't notice the "below " part. read it as above freezing first time. Now, if a system did that, I would hope it would re-activate if for some reason the occupants had "re-circ" mode turned on. As the occupants respire (breath) the humidity in the truck will rise due to moisture in our breath. Eventually condensing on the vehicle windows.

As I've said before, I wouldn't mess with the A/C.

Does anyone know: On my Highlander, the A/C is controlled by what is called an AC Amplifier board. It is a $600 part from dealer. Does the Taco have such a board? If so, any chance the OP could have inadvertently fried it? (hope not - circuit boards from Dealerships are notoriously expensive).

G

 

Well, that brings up an interesting point. The only temp sensor on the system is a thermistor located on the evap. The sensor itself is located in the center of the dash it appears, a real bear to get to.

I haven't mentioned it before, as it is listed in the trouble shooting section only in places where the compressor is not pulling in. Since you say yours is pulling in, I've ignored it.

You have checked all the fuses with a meter, not by eye, correct?

 

I thought about the amplifier too but as others have said the amplifier controls the compressor clutch and servos. All those parts work so my amplifier should be fine. If it were fried the compressor wouldn't kick on.

I think I'm going to give the fuses one last check with a multi meter, I only checked them by eye. If I can't figure anything else out I think I might have to bite the bullet and take it to the dealership. :headbang:

When checking fuses with a multi meter should I just test for conductivity or should I check the resistance?

 

When checking fuses with a multi meter should I just test for conductivity or should I check the resistance?

i would pull each and then test them with the resistance setting. my conductivity setting on my meter is flaky.

Also, if you suspect low on freon, take it to an AC shop first, probably cheaper, and they know AC better than the dealer. If its OK on freon, then go to the dealer

 

I just tested all the fuses with a multi meter. I am officially out of ideas. Looks like it's time to start calling shops to get it checked out.

 

got an appointment for the dealership to run a diagnostic on friday... hopefully its a cheap fix

 

Yes, hope so too. will you update us on what happens please?

That way, when others are searching for similar issues, find this thread, they will know what to do (or not haha)

thanks

Geoff

 

Compressor is working, Pipe is cold, Blower is blowing, Has to be a damper that switches from the hot/cold side.

 

The thing is the damper servo is moving. I can hear it and I can also switch between heat and cool air. It's just that the cool air is ambient temperature instead of AC cold.

I'll be sure to post up what I find out from the dealer. I'm just so sick of messing with it. It's not even that it's hot here It just really bothers me when things don't work the way they should.

 

Do you mean damper servo motor failure?

 

I bet the 134 is low. I know the chances are 100000000 to 1 that at the same time you fooled with it the charge went low.

But everything else sounds like it is working except you say the pipe is cool not cold.

Is the AC light flashing? When you put the AC on do you see change in rpm?

Dont tell the dealer you did anything, Just tell them it stopped getting cold. Let them tell you what happened:thumbsup:

 

First off, and not to rub salt in plurpimpin's wound, but for information purposes (I have extensive A/C experience), the A/C will not work on defrost when below freezing ambient temperatures, it will "cut out" based on the same temperature reading from the thermistor in the evaporator, as it does not matter whether the evaprator is below that temperature because of ambient airflow through it, or because the A/C system has been running. This is usually a few degrees above freezing, otherwise the evaporator core will "freeze up" externally from condensation, and the airflow will be blocked.

Secondly, it is a good by-product of the A/C working on defrost that the system gets used during the "off season", and thus circulates the oil through the system, which helps keep the seals and o-rings from drying out. I certainly would never disable this on my vehicles.

If the Low pressure side line (the big one) into the compressor is just cool, not cold,( ie frost on it when the compressor is running), then I would first suspect a low refrigerant level. Is it possible your wiring mod kept the compressor running constantly and overpressured the High side, causing the pressure relief valve on the compressor to open?

Good luck, keep us posted.

 

Cool I never knew that about the compressor in the winter. But your explanation makes perfect sense with the evaporator freezing up.

I've talked with a few other people that did the same mod and they haven't had the problems I have so I don't think the compressor stayed on. But I will check the refrigerant levels, everyone's reaffirming my suspicion of low coolant despite how illogical it seems. Everything else seems to be working properly.

 

I FIXED IT TODAY!!!!

I just recharged it with coolant and it works perfectly. Now I'll just have to wait and see if it holds pressure. If not I'll have to start looking for the leak but at least now I know what to look for. I'm hoping landphil's theory about the mod making the compressor run constantly and blow the relief valve is the case because then I'd be set.

 

Nice, Now leave well enough alone. If it isnt broke, Dont fix it:thumbsup:

 

thats the plan. I'm just crossing my fingers there isn't a leak anywhere.

 

How much did it take? If the compressor was kicking in then it was not extremely low.

 

It might have an RPM based thing too. Take a ford ranger - the fuel cutoff rev limit for their engines is 3000 rpm if the truck is sitting still. Once it's doing a few mph that limiter is taken off.

I bet the AC system has a similar way of handling it. The 2000 rpm AC cutoff at a standstill would be because any spinning engine at ~0mph is freewheeling and could very quickly spin up to a compressor-damaging speed if more throttle is applied.

Just my conjecture.

Wish my Hondas would have had an AC protection system. Spin those little single cams to 7000 when accelerating and the dang compressor would never shut off (very annoying if it kicks on during acceleration), and still it would outlast the car 9 times out of 10.

 

iroh could be correct, could be 2k at 0MPH, and higher once the truck is moving. Can't get to my copy right now, will look later today or tomorrow.

 

Probably is at idle. That whole section, including another where it notes the same thing, all deals with it at idle. So now I'm leaning toward the air mix door having temp problems since anything else shouldn't have fixed itself (like low freon, etc).

 

Flipped through the FSM wiring diagram, could not see any input of speed into the AC amplifier. There's a tach input and a temp sensor input from the combo meter, but nothing else.

Interesting, apparently it shouldn't work at freeway speeds, but mine sure seems to. I am not going to lose sleep over it, I am sure there is something hiding in there somewhere I missed. Just seemed perplexing at the time.

 

nervous to find out

So glad i found this...Im pretty sure i have a leak somewhere since this past summer (July) i had gotten the freon recharged/refilled etc at my mechanics and by October it was no longer blowing cold air again .....

I have 2 questions 1) how much $$$ might i be looking at to have this fixed ...high end and low end and 2) Will it hurt the compressor any at all if i use only the defroster / heater ( No AC button etc) until i get it fixed by mid spring?

I have heard differing things some say ill be fine but im a "worrier" by nature.... so please let me know and if possible explain to me why it will or will not hurt the compressor or anything else for that matter.

Much thanks in advance, A.