You need to replace the heater core.

 

did anyone come up with a solution to this?

i am having the same problem as the OP tried replacing thermostat and no luck also flushing heater core

heat is luke warm at idle but driving and revving in park gets hot,

also when **** is on blend of face and feet the a.c cylces, but when switched to feet or face only it does not



any ideas please help?

 

A/C behavior is normal for 98 and up trucks.

Need to back flush the heater core, and put the hoses back on with as little fluid loss as possible. (two people make this job easier.)

Then, take your truck someplace you can park it at as severe an angle as you dare, with the passenger side front highest. Burp the cooling system with the truck parked there.

 

Can you loosen a hose clamp at the bottom of the radiator and kinda crack it (lift it slightly) to see if air comes out? Also try it at the heater core?

This also use to be a symptom of a water pump being bad is it still that way?

 

Won't get any air out the bottom. Will get some coolant though.

The cooling system on these trucks aren't exactly ideal. The heater core is the highest point in the system, so, air likes to collect there..... and can cause all sorts of odd behavior.Getting it out can be fun..... I am tempted in install some of the "bleeders" like you see on the GM LXx motors..... just crack a valve, and let it go till coolant runs out. Close it up, and top off the system.

 

ive tried back flushing the core , is there any way i can put a bleeder near the heater core, or what is the best way to get the air out?


can you explain the exact process of burping the cooling system

 

Low heat output at low RPM is generally a sign of low on coolant.

Burping the cooling system is just getting all the air out. With your truck parked at the aforementioned severe angle, radiator cap removed..... (DO NOT TAKE IT OFF WHEN THE SYSTEM IS UNDER PRESSURE!) just let the engine idle, and the thermostat will cycle. (open when it gets hot, close as the temp drops) That should purge any air from the system.

 

gotcha my radiator is showing full of coolant, but i will try parking it on the hill,


how many temp sensors are on my trruck its a 99 2500 with 5.9 because my temp gauge only comes up between 130 and 210 so i replaced the thermostat with a 195 super stat and the gauge still reads the same

 

Just one. And the gauge in the dash isn't exactly known for its precision. You should run right around the 200 mark on the gauge. (when engine is fully warmed.)

 

yes its not reaching that, at all its exactly inbetween 200 and 130

im going to try to park on a hill tommorow