Hey all,
I just moved to utah from california and on the way out here i noticed that i had no control over my air no matter what i turn it to its always on defrost. also since ive been here my thermostat has been bottmed out and my heater dont heat up that much. Where do i start. anything at all would help. Thanks

 

Oh i forgot to say what truck it was. Its a 2001 24valve with 104k on it.

 

I would first check all the vacuum conections. Usually when there is a leak in the system it defoults to defrost. Are you saying temp. gage not moving from cold zone? If that's the case your thermostat needs to be replaced. Temporarily place peace of cardboard between radiator and intecooler see if temp. goes up.

 

DieseldodgeON is right. You have a vacuum leak. Probably one of the small lines running by the firewall.
Buy a thermostat. It is located right where the top radiator hose meets the engine. Easy R&R

 

OK I took a look at what i thought was my vacum lines but how do you tell if they are leaking? they seem to be in order

 

OK so i found out where my thermostat is located my question is do i need to flush the coolant when i replace the thermostat?

 

Your vacuum pump is on the drivers side below the injection pump. You will see a big vacuum hose coming up from it, and if you follow the lines you should be able to tell if they are broken or not. there is also a line that runs under the battery to the cruise control, on some trucks.
If you don't find any lines broken. You may be able to pull off one line and start the truck. you should feel suction on the line if you pump is working.

 

Good idea, but I don't think the OP's 2001 truck will have the big rubber hose from the vacuum pump. Only the older trucks with vacuum boosted brakes had that. His should have a small diameter plastic vacuum line, right from the pump up to the firewall. Same idea about following it from end to end to look for damage though.

 

You don't need to, but if it hasn't been done in more than two years, this might be a great opportunity to do so, since you need to open up the system anyway.

 

Isn't it the same diameter off the pump though?

 

Yeah, true enough, it is. It's a 3/8 or 7/16" adapter that converts down to one of those puny plastic lines.

 

Yep, that's what I thought. And those puny lines are what get brittle and break. "(

 

 

Thanks infidel. That pretty much sums it up.
To the OP. You should look under your truck for the 4x4 vacuum lines. ( I had forgotten about them). Could be coming from there.

 

This might seem silly but I had the same issue and it turned out that the control **** had cracked and was rotating on the shaft(with enough resistance that you would not even think it wasn't working) I could not understand why I could not change duct positions,It was when I was about to remove the panel and I pulled off the ***** that I realized the problem. Don't know if the 01 has the same controls as My 95,But worth checking,I have heard from others that its a common problem.