Heater/AC not blowing right temps

Anyone had this problem where the AC will start blowing hot air? When it happens if I move the gauge to hot and then back to cold it will blow cold again. Today I noticed cold air is blowing out of the heater too. Any ideas?

 

Casita 17 ft

 

Im having similar problem with mine. Blows cold AC but when i turn the dial to heat it clicks loudly and it blows cold. I was told today it's the flapper for lack of a better word and the shop said Toyota said its a $600 part or possibly more if it requires the heater valve and the cable end in the dash. Well on Rock Auto the heater valve is $27.79. Anyone have experience with 4seasons brand parts? Thanks. They also said that the dash will have to be pulled out to install it which will require several hours of labor. Anyone have any experience replacing one of these?

 

Mine does the same. If I open hood and manually move the heater valve I works. In gonna go With the rock auto piece and see if it fixes it

 

Heck I thought it was in the dash. Does the dash have to be taken out to replace it?
Also it's $105.79 on the camelback toyota parts website without the TW discount. I'm going to call tomorrow to see how much it'll be wth the discount.

 

It sounds like it's the blend valve thing that's under the hood at the top of the firewall behind the engine. The rotary dial inside extends and retracts a cable that attaches to that valve under the hood. They want how much to change that out??? Maybe I'm missing something here....

 

they said toyota told them the part was 600 and it would require pulling the dash which would be allot of labor on top of the 600. Neither seem to be the case. its a shame too. I thought they were a trustworthy affordable shop.

Im going to replace it myself with oem part and see if that fixes it. already watched a video on a t100 looks pretty straightforward.

 

Cool, yeah I think you'll be just fine in swapping that part.

 

Well turned out not being the heater valve located on the firewall but the blender unit under the dash. After picking the truck up at the mechanics (no charge)and taking it home I reached up under the dash on the passenger side a little left of the glove compartment and was able to manually push it over to hot while also turning the dial in the dash to hot. Then I jumped in the truck and went down the street and had great heat.
The retail for the Heater blower assy front which is what it seems like I need is $600 but I found it for $400 while studying the parts diagramt without being able to see it very well I can't really tell for sure. It has a cable hooked to it that's controlled by the dial. So that's where Im at. I have heat but if I want to switch between AC and heat I'll need to crawl down there and switch it by hand and I don't feel very confident about taking the dash apart to replace the part myself so we'll see. Maybe if I find a lower mileage wreck I can learn how to get it out so I dont do any damage to my truck.