Posting For a Friend, Tacoma Heater Problem

bucyouup68

Observer
I'm putting this in here because I know a lot of you drive Toyotas. Naturally this problem occured right after the warranty expired. Here's the problem:

When I turn the air conditioner or heater on the only place that the air will come out is at the defroster. I can control whether it is hot or cold by turning the cold-hot knob but I can't even shut the ac unit off. Even when the ac button is pushed off it will still blow ice cold air because the ac is still on (unless I shut everything off). I know in the past most vehicles had vacuum lines to the controls and if you had a vacuum problem then it would go to default which was all air to defrost. I have checked all fuses, relays, etc. All are good. All controls for control doors appear to be electrical not vacuum. All wiring looks good. I pulled the filter out, since it has a hepa filter, and cleaned it and stuck it back in. Of course that didn't make any difference but boy was it dirty. This is an 06 Tacoma. I took it down to the dealership today and let them look it all over. They were genuinely stumped. Have any of you guys had a problem like this before or know of someone who has?

I'm hoping to avoid mega bucks repairs.

Any Help would be appreciated.
 

nvprospector

Adventurer
bucyouup68@sbcglobal.net said:
I'm putting this in here because I know a lot of you drive Toyotas. Naturally this problem occured right after the warranty expired. Here's the problem:

When I turn the air conditioner or heater on the only place that the air will come out is at the defroster. I can control whether it is hot or cold by turning the cold-hot knob but I can't even shut the ac unit off. Even when the ac button is pushed off it will still blow ice cold air because the ac is still on (unless I shut everything off). I know in the past most vehicles had vacuum lines to the controls and if you had a vacuum problem then it would go to default which was all air to defrost. I have checked all fuses, relays, etc. All are good. All controls for control doors appear to be electrical not vacuum. All wiring looks good. I pulled the filter out, since it has a hepa filter, and cleaned it and stuck it back in. Of course that didn't make any difference but boy was it dirty. This is an 06 Tacoma. I took it down to the dealership today and let them look it all over. They were genuinely stumped. Have any of you guys had a problem like this before or know of someone who has?

I'm hoping to avoid mega bucks repairs.

Any Help would be appreciated.

From what I read this is what I concluded.

If you are getting heat when you cycle through the temp your Air Mix Control servomotor is working. Since you are getting air from the out side in the cab the Air Inlet Control servomotor is working. What this leaves is the last servomotor, the Mode Control servomotor. Since you already checked fuses and wiring that rules out those issues. What you need to do is check the mode doors for both heating and cooling to make sure they are opening and closing. If the doors are working test the servomotor and see if it is with in specs.

What your describing is not going to be major bucks, well I haven't priced servomotors lately. It is not a major repair and should only take a few hours to do. Worse case is the ECU is bad, but I highly dought it.

-- Edit -- Removed some opps
 

Clark White

Explorer
Not that familiar with the heating systems of modern Tacoma's, but I do know that when you turn the defrost on, it turns on the AC with no option to turn it off (drives me nuts when its cold as balls!). Your problem might also be a short or open in the wires going to that servo? I don't know where in the system the AC gets turned on, but the symptoms would fit either of those to a T, depending on what exactly turns the AC on with the defrost.
 

nvprospector

Adventurer
When defrost is selected in any vehical that has A/C after '70s the unit is turned on automaticaly. It is because A/C is a dehumidifier and it is removing mositure from the air. Thus helping with removing the conditation from the atmospire of the cab allowing the windscreen to de-cloud.

Also, a lot of A/C failures in older models of vehicals in the '60 and '70 was do to the seals of the A/C pump becoming dry and brittle in the winter. Using the A/C to help with defrost forces us to run the A/C pump so there is less chance of it failing later down the road. But for you in colder climents will notice that the A/C pump does not engage below 0 degrees. Again this is a protection factor of the A/C pump so it won't freeze up causing damage.
 

Clark White

Explorer
Using AC with defrost makes a world of difference! I just wish I had the option instead of it doing it on it's own with no shut off. Once I have defrosted the windshield, I don't need AC anymore, but I still want defrost to keep the windows clear. It's really not that big a deal, its just at the very bottom of my list of modern automated annoyances. My girl friend calls me old fashioned... :shakin:
 

DaveInDenver

Middle Income Semi-Redneck
nvprospector said:
When defrost is selected in any vehical that has A/C after '70s the unit is turned on automaticaly.
My 1991 Toyota does not do that. There is a A/C button that turns the A/C on or off, no matter what vent is selected. I dunno when that changed, but apparently in 1996 with the Tacoma. I can run my defrost with or without A/C, driver's choice. And I like it that way...
 

nvprospector

Adventurer
DaveInDenver said:
My 1991 Toyota does not do that. There is a A/C button that turns the A/C on or off, no matter what vent is selected. I dunno when that changed, but apparently in 1996 with the Tacoma. I can run my defrost with or without A/C, driver's choice. And I like it that way...

In my '07 Taco I can turn on A/C with any vent or heat setting selected. That is common because all you are doing is mixing hot and cold. What I was saying is that when you have the mode switch set to defrost, the A/C compresser kicks on and off to help dry the incomming air into the cab. You do not need to have the A/C turned on to have this happen. With your A/C button OFF, turn your mode switch to defrost. Pop your hood and watch the A/C pump. The clutch on the pump will cycle the pump on and off.

On my disco d2 the A/C is on all the time no matter what the temp is. The only time you can kick the compresser off is to select the Econo button. And then it is still a hit or miss that it will turn itself off.
 

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