Calling all A/C gurus out there

Mine has been doing this for a couple years intermittently. Like others have said, it's most likely the blend door actuator. The short term workaround is to set the control all the way hot, and then switch it back to cold. If it starts blowing cold you'll know that's the issue.

 

Watch and listen to end of this video. Same frequency/rhythm of vibration but the tone is different because it was recorded from under dash vs driver seat.
https://youtu.be/HG5k4zpjuWQ
Servo motor of blend door actuator.

 

It seems as if it only does it when the fan is NOT in the OFF position (anything low and higher) but I’m assuming that’s more so the case because when the fan is in the “off” position I believe everything in the AC system would be off. I could be wrong about that though.

 

I haven’t dug deep into anything yet. Honestly though, the truck is driven every single day and not like it sits for a while. I also don’t live in a rural area either (not that we don’t have mice, just plenty of other places to make shelter) so I would be surprised if mice made their home in there. Not impossible though

 

I agree this kinda sounds like it could be similar however mine is less of clicking noise. Like somebody said earlier it not only sounds like driving on the rumble strip of the highway, but also feels much like it too. I would say about 50% of the rumble but the same frequency. Point is, it’s not only audible but felt as well

 

It doesn't take much to throw the wheel out of balance and make it make noise but the switching from hot to cold is most likely the servo motor.

 

Anybody know anything about the location of the ac relay on a 2000 taco?

 

There is no relay for the compressor, it's controlled directly by the A/C Amplifier which is powered by the 10 Amp A/C Fuse.

 

Update: So after getting incredibly irritated by the baby birds sound under the dash, I removed the blend door servo motor yesterday. to my surprise that's what was making the continual random squeaking noise. I didn't really think this was possible because I assumed once the temperature control was set to position, the servo motor wouldn't move there after unless the temperature control was changed. well I think my theory stands correct, but in practicality it was wrong. When I removed the motor, it was still plugged in to the harness. I let it sit on my floor mat while I grabbed a small flat head to depress the clip on the wiring harness to unplug it. when I did so, I noticed the servo arms twitching. It was in the "cold" position but it was randomly moving about a 1/8 of an inch back and forth. Not gaining in either direction just twitching but maintaining the same area. Found this very strange. I removed the motor and tested it by attaching the #4 & #5 pin to 12 +/- and vice versa. The arm moved as it should without any twitching. I opened it up and checked the gears as well. No stripping. When I plugged it back into the harness to see if it would twitch again while connected to the truck I somehow noticed that if I pushed in on the fan speed knob, it would make the arm go about 1/4 turn further into the cold position. My initial thought was maybe it wasn't going as far as it should even though the temp control was at its coldest and that's why I wasn't receiving cold air. So I reached under he dash to see if I could move the valve any further manually. It was maxed out where it sat. I'm confused by all of this but at least I know now the blend door servo isn't stripped and I was able to diagnose that annoying squeak. I'm questing if there is an issue with HVAC control module though.

I took some videos and will post them up as soon I get the chance to upload them.

 

ok you are on the right track. mine did the exact same thing I was at my wits end. Now the next time you have that issue try pushing hard on the temp control knob you will here a sound and then it will turn cold. It might stay that way the rest of the day or it might last 15 minutes. It is in the temp control module. I'm having a blonde moment and can't remember what type of switch it is called but we are not the onlt ones. Now if you are cheap like me I can tell you hoe to remedy this. Go under the hood there is a block on the fire wall almost center behind the engine, it controls the water flow to your heater core. unhook the cable make sure it is in closed position and zip tie it where it can't move leave it alone and you will have ac as long as you want it. Winter time hits cut zip tie and rehook cable. This makes summer number 2 for me doing this.

 

I like your method lol. i might use this as a temp solution. this Block or valve if you will exists on the 2003 model? for some reason i thought i read somewhere that wasn't the case as the newer models weren't cable driven. i could be totally wrong about that though. glad to see I'm not the only one though. also happy to see that i might be getting somewhere with this.

 

If it has been non-functional for years, then the problems are likely compounded.

Take it to an automotive AC shop.

The system may need a host of parts beyond just a shot of freon or a relay.

 

I’m sure there is more than one issue going. Almost without question. I’m at least trying to narrow it down before throwing more money than the truck is worth at it though.

 

There was a write up on this as well. I remembered what type of switch it was called. They said it was a reostat type, some even said you could pull the knob off (temp control) and spray contact cleaner in behind it and it sometimes would help for a while. Otherwise you would have to find a whole climate control module off of a wreck, salvage yard, or buy new from dealer. They are pricey. My method may be primitive but it works for me.

 

Why is it that when someone is asking for help and trying to figure something out themselves your suggestion is don't, go to a professional. You said the same in another ac thread. OP seems to have the capability to fix this himself.

@Sprunx looks like you're on the right track and have gotten good info so far. If you need any of the fsm documents let me know, I've got the 01 hard copy and a digital.

 

I would wager most DIY mechanics do not have the equipment or knowledge to repair the AC in the truck. Specifically the OP said, "....I don’t know much about the AC systems."

If they have the knowledge and equipment, then why are they asking internet strangers How To fix????

AC systems are not simple. Many components, high pressures, toxic gas, gas needs to be captured not released to atmosphere.

Yes, I'll recommend hiring a professional with the knowledge and equipment to do the work on an AC system.

 

Because someone asks for help doesn't mean they're not capable.

I knew nothing about ac systems before fixed mine, trouble shoot the problem, get shop to evac the system, fix problem, have shop pull vacuum and fill. No special tools required,b way cheaper, and now he'll know how it works.

I knew nothing of regearing, brake jobs, timing belts, suspension running cnc equipment, machining, the list goes on. I had no or very little "professional" guidance, a bit of help from the interwebs and books. I'm no genius, you don't need years of training, just a bit of help from folks like us and doing it. Yeah mistakes will be made, money lost, but in the end you gain knowledge and self reliance.

How bout offer the advice that's needed and asked for, not what the op didn't ask for.

OP sorry to derail the thread, dude just annoys me.

 

You can always place me in your ignore bin.

I see no reason to debate with you. I offered honest suggestion to the OP based on the OP's original post. If you don't like it, then ....... well, you've said nothing to change my suggestion. To each their own.

 

I have had 2 family memebers with intermittant magnetic clutchs in the last month... they were not Toyotas. Same symptoms, the AC works when it wants to and I was fortunate to have the gages on the systems when the clutch would fail so I knew it wasnt an over/under pressure issue.

 

Gonna revive this thread a little bit as I believe I've made some MAJOR headway. So it wasn't long after I made this thread that fall set it and the AC went to the back burner again. I never did get it figured out.

Last week, I finally said f**k it and took it to a shop to have it looked at. They diagnosed it as an amplifier issue since they had absolutely no power going to the compressor. Quoted me 530 bucks for a new AC amplifier with install but I was reluctant to move forward for 2 reasons. 1) being that with the multitude of issues going on, I wasn't confident this was actually gonna fix my problem as the pressure switch wasn't ruled out and admittedly many years ago I tried adding refrigerant to system without really knowing how. Basically, I didn't wanna throw 500 bucks at a guess. If it was 100% then I probably would've paid the money. Second reason was (and I hate being this guy after going to a mechanic but) I have a couple bulbs flickering behind my gauge cluster that I've been meaning to replace and figured I should just replace them and while I'm that far, I will be at the amplifier / climate control module anyway.

So with the intent of maybe finding a used one to try off eBay (since the amplifier is a discontinued part) I took my dash apart last night to get the part number off the amplifier & control module so I could verify that I found the right parts to order. after taking pictures of part numbers, I reassembled everything. When I was putting the climate control module back in the one harness that connects to the amplifier fell out of plug in the back of the amplifier. I thought it was strange but pulled it back out to reconnect. The harness wasn't in far enough to clip in but when pushing it didn't seem like it want to go. with a little muscle (and no longer scared of breaking anything since it barely worked anyway) I pushed it the rest of way in, enough for the harness retention clip to engage. Well come to realize I don't think the plug has been fully plugged in this whole time. I guess it was in enough to get some function out of it but not enough for it to do what its suppose to do. I don't want to talk too Soon but the AC has been working since last night when I put all this back together. FINGERS CROSSED. not only did the AC come back to life but the Mode actuator (the motor that controls the air flow / vent selection) has come back to life too!

The only remaining issue I seem to have is when screwing with it last night after it started working, is that a few times when I would go all the way to the highest fan setting, it would blow cold AC for a few seconds and then you could literally hear and feel the air flow change and then it would start blowing HEAT! Without touching the temp knob at all! If i turned the temp knob to heat and then back to cold it would go back to cold again. It did this a few times but not every time so its kind of of finicky. when I've tested the blend door actuator using a 12v source, it appears to work as it should without the jerking, spazzing, or twitching that I described earlier in this thread. obviously something is making it turn back to hot though. I'm confused on how to isolate this issue and try to figure out if its the actuator motor itself, or the climate control module that's sending a bad signal somehow. I guess I might just buy a used control module and see if anything changes. unfortunately, that's gonna be like 200 bucks to play around and either fix the problem or eliminate a possible culprit.

I know this is long winded but I hate when people never post their solution to a thread for others to use, which seems to be more common than not. I will continue to try and figure out why the temps are changing on their own and hopefully my AC continues to work reliably throughout the day today.