Heater always on

I have a 2002 4 door prerunner. My heater stays on all the time. Do I need to change the heater cluster or the amplifier. Can anyone help me.

 

When you say on, do you mean its always hot or wont change from floor to vents. Can't control temp.? need more info.

 

The heat is always on. It will change from defrost to vent to floor. It just won't go cold even when it's on cool setting

 

Check the water valve outside and see if it moves at all when changing temp. Its on the center of the firewall with 2 hoses and a cable going to it.

 

Have someone move the heat control while you observe the heat control valve. The cable might be broken or merely unhooked, or the valve itself might be bad. Start by seeing if the cable moves...

 

2002 is differant then 2003 and 04 correct?

 

Thank for the advice. I'll check those things and get back to you guys

 

So I checked the water valve. It seems to work fine but the cable doesn't move at all. I unhooked the cable and tried to move it and it doesn't move at all. What do I try next?

 

Try shooting some PB Blaster into the cable end from the firewall side, let it soak a while, and see if it might free it up. Could be rusted internally. If that doesn't help, you might have to remove the cable from the housing, and replace it.

 

I have the problem where heat comes out of the vents when the air intake is taking air from the outside and not recirculating air from the interior. When I switch the air intake to interior there's no more heat. Is that normal?

 

Sounds like a problem with the flaps that direct heat through the heater core and into the vents. Something isn't moving the way it's supposed to.

 

I lubricated the cable the best I could. With the cable unhooked the water valve work perfectly when moving it by hand. The temperature changes like it supposed to do. The e cable doesn't move at all. Not sure how the other end of the cable is hooked up.

 

You will need to trace the cable under the dash to the heater control. Don't remember if a 1st gen has a slider, or a knob that changes the heat setting...

 

Has a knob for temp. Control

 

Next step would be to remove climate controller (were the knobs are) and see of something it broke. I'm unsure and haven't been able to find out if 2002 is like 2003-04. 2003-04 is controlled by motor were the older ones had a cable. you might be able to look under glove box and see if it has this motor.(see attached pdf ) If not its manual cable controlled by knob. If it does then there's also how to check it in file

 

I have the same problem but you're likely not going to move that cable freely by hand. The other end is hooked up to a servo motor under the passenger side dash (fairly easy to get to) which is likely the culprit. My valve moves freely and the cable will actually move but its really erratic and not responsive when I use my HVAC control inputs. For winter I have just manually opened the valve so I have heat when needed. I'm trying to source a servo motor and maybe HVAC panel to try and fix this.

 

Sounds like a cable is switched around. You sure when you switch to interior air it does. Does sound change from outside to inside air?

 

See the pdf I attached it has info on how to check servo motor

 

Thanks for all the info. Now I'll try to get my fat butt under the dash to check the servo motor

 

I don't think my climate control is electronically controlled. I have the fully mechanical one on my '98. I have a latch that you have to push/pull to change air circulation. You can actually hear a damper physically open and close when you switch them. If I'm not wrong all the climate knobs work mechanically with metal wire.