hot air comes thru vents

Yeah the '01-'04's have different HVAC controls than our older trucks.

 

I second that.
Older Tacoma 1st gens have the slider style selector and the later model 1st gens have the rotary knob style.

 

I have the same hot air blowing issue. The bottom of the trucks dash is off so I'll have a look to see if the temp selector is electronically controlled or cable.
Just to throw my 2 cents in, I understand that when the fan is set to off there is still some are blowing through the vents, thats kool.
The issue is the temp in my truck is stuck on full hot and nothing will change that, not even turning the ac on.

 

There's actually a third style, the '98-00 still utilize cable controls but went to a turn knob style. While the late models have the electronic turn knobs...

 

Awesome, thanks for adding to the info!

 

+1. have someone turn the knob inside and observe if its moving the lever on the heater valve. Mine is also the style with manual turn knobs for heater mix and vent control.

 

I found this in the service manual.
I have an issue where regardless of where the temperature control is set only full hot air blows.
I am going to go through these steps and see what I find

 

Quick fix for those that have infrequent function of dash control knob:

I have the same issue where maybe 10% of the time am I actually able to manually switch from cool to warm from dash control.

After looking at the cable exit point under the hood at the firewall it appears that the cable rarelyoves the switch from driver side to passenger side, passenger side being the cold direction of the switch.

It's almost as though it meets too much resistance to override although I did note that the cable only intermittently moves in and out even when disconnected from the switch. If you slide the cable off of the trigger of the switch you can manually move the trigger towards the passenger side and have functional cool air for summer months, then move it back towards the passenger side for winter months. Fall/spring are a bit tricky, but hopefully this helps until a solution is found.

 

I have a 98 with the turn style knob. I have to pop the hood and move that cable slightly in the coolant bypass to get full cold AC. If I move to hot it will not return to cold unless manually move it. In my situation it's either the cable or the coolant bypass valve. Don't know. I just pop the hood, look at the old 3.4 and manually move the cable for some AC. I'm surprised my 98 has ac still so I don't mind. Haha

 

I've been having similar issues with my dial on my 99 clicking loudly when I try to turn on the heat when it meets the resistance from the cable under the dash so I've been reaching under the dash and pushing or pulling the lever that controls the blender door while turning the knob with my left hand and it's been working so far. Hopefully another couple weeks and I can leave the heat on

 

Hey guys I am new to the forum but I just had the same issue with my 01 Tacoma. It was intermittent and would default to heat. Moving the know around would usually get it working after a while so I figured it was something with the control itself. I took it apart and disassembled the control and found two broken solder joints for the temp control knob. I resoldered the joints and put it back together and it works perfectly. This issue would apply to the 01-04 models. I can’t promise this is your problem but it is worth a look since you are going to be replacing that control anyway. It is easy to disassemble and the get to the back of the knobs. I posted a few pics of the spot that was cracked. Hope this helps someone else.

 

Ok quick update. After about ten minutes it started acting up again. I could still fix it by playing with the control knob so I took I back apart and de soldered the temp control varistor switch from the board and carefully opened it up. You have to be very gentle when de soldering so you don’t damage your board. I had two spots delaminate but they fortunately were not actual circuits so it worked out. Once the switch was out I had to bend a few tabs to expose the contacts. Pay attention to the orientation so it goes back together the correct way. I would mark the housing before taking it apart. Inside there are several wiper contacts and carbon tracks which allow the switch to change the resistance and tell the board what position to put the blend door in. I gently cleaned the carbon tracks with contact cleaner and a Q Tip and I very gently bent the wipers out just a smidge to tighten up the connection. Then I put it all back together and re soldered it to the board and re assembled and tested. Now it works perfectly and hasn’t given any more problems. I am posting a few pics for reference. If you have never soldered or de soldered board components before I would recommend finding a friend who has or practicing on a junk board from and old computer or appliance before attempting this. It is easy to screw up and then your control is shot. Hope this helps.
-Nathan

 

Thanks Burnat72, I had the same issue on our 2001 Tacoma. I'm so glad I found this forum. Your posts allowed me to fix my hvac controls even with my limited soldering skills, and save a couple hundred bucks, thanks!