Was having heater issues about a week ago on a long drive and my temp gauge was fluctuation a lot. So I went and put a new t-stat in (195 unless the parts store screwed up). Put it in and put a rug over the radiator ( I live in North Dakota and its been below zero the past 2 weeks and its not going change) and secured it in place. but i was test driving today after work and the needle on climbs half the gauge then stays and doesn't move. And my heat has gotten worse and colder now. Heater core is hot and the blower motor blows. I can't take much more of this cold. Any suggestions for the lack of heat and possible over cooling? Btw 2001 Ram 1500 5.9 L Magnum
Here is a picture of where the gauge stays

 

That's pretty much where the gauge on my 98 stays as well. The gauge is NOT linear....... (I made the mistake of changing the thermostat, before actually plugging in my scanner, to see what temp the PCM thought the motor was......)

You probably have an air pocket in the heater core..... these trucks are notoriously difficult to get all the air out.

 

Gauge looks right. Should be nice and hot. Although when it's that cold, it can take an hour of hard driving to get any real heat. I've been through there in -20 deg. Door wouldn't even latch, ha. Took me from Selby to Watertown to take my coat off one year.

 

Thanks guys, I know the cold has been wreaking havoc on vehicles up here, most just can't handle -30, I'll try to burp the heater core and/or back flush it, but to back flush I'll have to bring it in because no out door hoses this time of year.

 

Try putting a 'flush T' in the line on the drivers side, as close to the heater core as you can get it. Start the engine, and just let it idle. Crack open the flush T a little bit, and let it purge the air out. See if that doesn't improve your heater performance.

Theoretically, it should get the last of the air out of the system. Highest point in the cooling system, and all that...... I want to try it on mine, but, with the 8.0, there is this big intake in the way..... Makes life difficult.

 

Did you happen to inspect the coupling for the blend door? Common problem.
https://heatertreater.net/dodge-ram-95-02

 

Good point. His is an 01. Missed that tidbit.

 

Interposer.

99-02 trucks.

 

@Ramman18, go on? Sorry not catching what you mean.

 

That's what that part is called: the blend door interposer. It's a part that breaks on 99-02 trucks when they went to electric blend door motors. Mine went in 2013.

The above heatertreater link is the fix.