hot/cold temperature works intermittently

have a 2005 TRD manual shift 4x4 Tacoma

The hot/cold temperature dial works intermittently. I start the truck in the morning to warm up and set the temp to high to defrost the windshield. I come out after 10 minutes and have nothing but cold air blowing on the windshield. I fiddle with the temperature dial, moving it from hot to cold and it eventually starts flowing hot air into the cabin.

I took it to my mechanic this morning and he says it's working fine and can see no reason for my symptons. He suggest I wait till it completely fails to then find out whats wrong. I don't like this solution with winter rushing rapidly towards us in upstate NY.

Any suggestions on what to check out or what could be the issue and fix?

Thanks!!!

 

I would change out that temperature dial. Just get the whole panel at the junk yard.

 

Thanks for the feedback! I'll see what I can find.

Any other suggestions from the masses?

 

I had similar issues with a temp control panel in another vehicle and it turned out that the connectors needed to be disconnected and reseated. There are a lot of small pins on them and occasionally some loose their connections due to vibrations or corrosion. Its worth a shot since it costs nothing.

 

Sounds like a loose connection.

 

Thanks, I'll check it out once I find them. Anyone know where to look?

I was also thinking it could be a heater control valve?

 

carparts.com

 

I just took mine out to run some wires to the radio.. when I put it back it didn't work right.
The plugs seem to be pretty sensitive. I'd plug and replug em and see how it goes.

I took it out .. pushed on the harness and it has worked fine ever since.

If not. These type things (for all cars, I didn't check tacoma) are very frequently sitting on ebay. easy to take out.. but not much demand.

 

There are 4 plastic tabs that hold the control unit in the dash. They recommend taping the tip of a screwdriver and prying t each of the 4 corners of the A/C Heat control panel to disengage the 4 clips. Two connectors are on the back of the panel.

 

I'm going to work on this today and will let you know all what happens.

Stay tuned.

 

So I disconnected the air conditioning console and then disconnected and reconnected the plugs. It had no effect on my issue. I still had no heat for awhile. It's strange, Once I start driving down the road the heat kicks in with no problem through the vents into the cab, but when I start the truck to warm it up in the morning no heat through the vents even though the temp guage says the truck is warm. Once I start rolling, heat starts flowing, weird?

I check the 2 heater hoses going into the heater core inside the engine area. The top hose was hot to the touch but the bottom hose was cold eventhough the engine was hot!

Any ideas on what to do with this info, Flush the heater core? Replace the heater core? What? I'm stumped.

Thanks for all of you help everyone!!

 

The lights on my dial only work sometimes. I wonder if I should get a new panel

 

Just replace the bulbs. They can be removed with a small flat blade screwdriver, just pop out the controller and they are on the back, they are the brown round things. Have to get the bulbs from Toyota, no aftermarket bulbs available. I've done this on a Tacoma on my jobs used car lot.

 

Not that it helps you, but I seem to be having the same problem... When I start the truck, it blows cold. It will warm up if I bring up the revs a little. Today I noticed I heard what sounded like water running through the dash, and the heat started up a little more...

I'm a little nervous with winter rapidly approaching... I've been doing some looking around, and haven't found any solutions or anyone with quite the same problem. I was thinking of getting a coolant flush, but I'm not sure that will solve my problem.

 

It could help. If you hear the water sloshing around it means there is air in your cooling system and the sloshing is the heater core filling up. You may also consider unhooking the heater hoses and flushing the core out with a garden hose.

Also refer to this thread - http://www.tacomaworld.com/forum/technical-chat/123962-hot-cold-temperature-dial-not-working.html

 

I'm going to flush the heater core today and will let you all know if this fixed the issue!

Thanks for all of your feedback!

 

Ya I bet thats clogged up, I was acutally thinking this as I kept reading through the thread. The outlet hose should be pretty warm coming out of there. I bet thats clogged up. Hope you get it fixed.

 

Graham, please keep us posted.

I did notice this morning that my reservoir is fine for coolant levels. However, I checked the radiator (before starting the truck this morning), and the there was more air pressure than I would have expected and I couldn't see any coolant. After I got to work, I pulled into my parking spot and sat there for a minute. The defrost slowly switched to cold air. I brought the revs up from idle to 1500, and the defrost warmed right up...

... I'm going to top it off at lunch today, but I am really interested in what happens with the flush.

Are you going to have it done at a dealership?

 

Success!!!!!

I flushed the heater core at lunch. I ran water through a garden hose through both lines about 4 times each till the water ran clear. Really wasn't to much discoloration. I then took off the radiator cap and put a funnel half filled with fluid in the radiator top and ran the engine for 20-30 minutes to get any trapped air out.

I turned it off and let it sit till the engine was cold then started it up and switched on the heater to warm the cab like on a cold morning. I went in the house for a sandwich and came back 10 minutes later and was met with nice warm air flowing through the vents. I am now ready for winter!

Thank you all for your help! This forum is always a great resource for me and helps me avoid going to the dealership or local mechanic.

 

Nice, glad you got it fixed.