A/C / Heat turns off by itself.

[VernySanders]

I'll have it on full blast and it will shut off. Intermittently. But getting worse over time. The first time it happened I just moved the switch from off to HI and immediately the unit turned off. Does this have anything to do with my pulleys? (Bearing going out) of is this electrical?

 

[jgue467]

What MY ya' got?

I'd guess right now at electrical and it is giving a warning of where it's headed so act promptly....maybe get FSM and test controls for current, resistance, etc?

 

[Bad Luck]

I'll have it on full blast and it will shut off. Intermittently. But getting worse over time. The first time it happened I just moved the switch from off to HI and immediately the unit turned off. Does this have anything to do with my pulleys? (Bearing going out) of is this electrical?

Full blast what? Heat or cold? AC on or off?

 

[alumarine]

Is it the fan that turns off?

 

[VernySanders]

Full blast what? Heat or cold? AC on or off?

its only happened on full blast, its the actual blower though, so a/c on or off hasnt made a difference, nor has the actual temp of air blowing through. It will go from full blast to zero flow, as if ive turned the actual unit off. It doesnt slowly happen though its an instant thing.

 

[VernySanders]

Is it the fan that turns off?

yes but it must be all the fans in the front of the vehicle because it happens to both sides at once.

 

[VernySanders]

What MY ya' got?

I'd guess right now at electrical and it is giving a warning of where it's headed so act promptly....maybe get FSM and test controls for current, resistance, etc?

Ive got a 2000 SR5 with 260k on the clock. Thus far many of the parts I have replaced have appeared to be what came on the truck 20 years ago.

 

[pluton]

So---the blower motor (fan) is intermittently going on and off, right?
1. There's only one blower motor. It's under/behind the glove box.
2. I'd test the motor to find out if the motor is intermittently going off, or the power to the motor is intermittent.
3. My hunch: Likely to be intermittent power---Could be bad fan (blower) switch, or bad blower motor resistor. Or, if you're lucky, a simple wiring connector that is loose and easily pushed back into place.
Intermittent electrical failures are sometimes tedious to sort, but you have to decide the balance between the tedium of waiting for it to fail against the cost of just blindly replacing parts.

 

[Bad Luck]

its only happened on full blast, its the actual blower though, so a/c on or off hasnt made a difference, nor has the actual temp of air blowing through. It will go from full blast to zero flow, as if ive turned the actual unit off. It doesnt slowly happen though its an instant thing.

Here's a link to a 2000 EWD for ac operation. Dropbox - 2000 4Runner Electrical Wiring Diagram (EWD383U) - Printable - Simplify your life If you scroll down to the 3rd page it lists power flow for HI operation. Under high operation there is no power going through the blower motor resistor so that would lead me to believe you have a blower motor speed switch problem. If it was a power/ground problem then it would likely happen at other speeds than HI.

If that link doesn't work here is the whole 2000 EWD. You're looking for section 244. Dropbox - 2000 4Runner Electrical Wiring Diagram (EWD383U) - Printable - Simplify your life

 

[Captsolo]

Is it the fan that turns off?

Had a bad fan once in my 2005 4runner. That's my best guess!:zoom:

 

[brillo_76]

+1 with Pluton. I agree as its most likely one of those things.

When the blowers go bad they mostly wine for a while. Or they will not start and have a dead spots on the armature. Once in a while, they will burn up while your driving. I had that happen in a 87 Toyota pickup truck. Filled my cab with smoke when it went. That was fun to roll the windows down when that was happening as I couldn't see a thing in less then 10 seconds. So good thing our windows are power windows on the 3rd gen.