I have an 02 Ram QC 4wd. about 50k on it. Winter is here and I just noticed that i wasnt getting any heat. It seems that when I punch it or get on the highway the heat comes on. I assume that there's a heater control valve that is probably control by vacuum. Can anyone confirm this and if it is vacumm controled, where is the valve so I can trace down the tubing.

Thanks

 

I'd do a coolant drain and flush and also disconnect the heater hose and take a garden hose and blast some fresh water through there. Top off and then test.

Sounds like you are either low on coolant or the heater core is starting to plug up on you. Flush it now before it causes problems.

 

I'm with Doc...most times that I've seen no heat until higher RPM it's caused by low coolant...there just isn't enough circulating to get to the heater core at low water pump rpms.

 

When you figure out what was causing the heat problem please let me know I have the same exact problem and have not been able to find out what it is. here is my email monoxide83@hotmail.com

 

So many posts have the same issues, seems like I chimed in on a post like this recently. You very easily could just have air in your system. "Burp" it. If you recently flushed or drained and refilled your system this is probably the issue, if not try it anyhow, it is free and easy. I have not had to do it to my Ram yet so I can not direct you to the bleeder screws, maybe someone else can help there? On my past newer cars the bleeders are usually located near the thermostat housing.