Idle Speed Changes When A/C is Off. Anyone Else?

[TEGSTEG]

I have an '01 Tundra V8 EC 4x4 and noticed a problem about a month ago. While at a stop, it's as if the a/c is cycling and the idle speed changes,but the A/C is not on (At least the light isn't on). When I press the A/C button the light comes on and sometimes the idle speed changes, sometimes it doesn't. Since it was raining at the time I noticed it, I didn't check to see if there was condensation under the truck since I thought it might be rain water leaking from underneath the truck. It has been dry for a few days now and I just got back from a 1 hour drive. I looked underneath the truck and under the hood and sure enough, there is water dripping from the evaporator drain on the firewall. Does the evaporator drain water even though the A/C is off? Is my A/C really running even though the switch is "off"? The temperature does seem cold at times though not freezing. Has anyone else experienced this? Any help would be greatly appreciated!!!

[LGL002]

Originally Posted by TEGSTEG

I have an '01 Tundra V8 EC 4x4 and noticed a problem about a month ago. While at a stop, it's as if the a/c is cycling and the idle speed changes,but the A/C is not on (At least the light isn't on). When I press the A/C button the light comes on and sometimes the idle speed changes, sometimes it doesn't. Since it was raining at the time I noticed it, I didn't check to see if there was condensation under the truck since I thought it might be rain water leaking from underneath the truck. It has been dry for a few days now and I just got back from a 1 hour drive. I looked underneath the truck and under the hood and sure enough, there is water dripping from the evaporator drain on the firewall. Does the evaporator drain water even though the A/C is off? Is my A/C really running even though the switch is "off"? The temperature does seem cold at times though not freezing. Has anyone else experienced this? Any help would be greatly appreciated!!!

The a/c compressor also runs if your vent position dial is in the defrost or partial defrost mode (last two positions on the right of your dial). The windshield/radiant markings at these two positions tell the story. The a/c light doesn't illuminate during these modes. The idea is to dehumidify the cab interior to reduce fogging of the window (windshield & front door glass) interiors. Move your dial to another mode and the a/c button and it's light come into play.

Larry

[TEGSTEG]

Larry,

Thanks for the response. I understand the dehumification process with the windshield defroster. But what I don't understand is that if it is in the windhield defrost position, I have no control of the A/C? In my Honda/Acura, if I turn on the defrosters, the A/C comes on, but I can hit the button and it turns off. Are you saying that I cannot do this with the Tundra short of disconnecting that feature? ( I just saw the post on how to do this ) Once again thanks for your answers!!!

Teg

[bidman67]

Ever since I have switched off a selector position using the AC I have not had a problem with the "Thunk" that I thought was coming from the drivetrain when coming to or reching a stop.

[TEGSTEG]

Originally Posted by bidman67

Ever since I have switched off a selector position using the AC I have not had a problem with the "Thunk" that I thought was coming from the drivetrain when coming to or reching a stop.

Yeah...I noticed the thunk too. So did you just switch the position to, lets say, the air in the face position?

[ThundraSpeed]

Bump... Ive got it too w/ air in the face position, and ac off fan off.