The cooling system is not functioning properly. It occasionally runs hot, but nut overheat. The coolant is back-feeding into the coolant reservoir and then the system gives a "check gauge" signal as the temperature gauge indicate a high temperature condition. I got the truck after the owner changed the water pump; I changed the radiator soon after. The problem persisted so I changed the thermostat and the radiator cap.
What would cause the coolant to back feed and cause the AC to blow hot? the AC blows hot even when the cooling system is in the normal operating range. The refrigerant level was checked.

 

Your heater core is probably clogged.

 

Heater core,or something ,how do you clean it,thanks ahead

 

You could try getting a radiator flush done at a local shop, you you can pull the dash apart and pull the heater core out and boil it.

 

i back flushed my heater core using a old garden hose hooked the hose to the out flow side and another peice to the in flow side and turned it on had all kinds of black goo come out but i did that cause i had no heat inside

 

also look into the heater control valve if its not functioning itll cause your heat and a/c fight one another

 

Clogged heater core. My 2000 did the same thing until i back-flushed the heater core. All sorts of stuff came out of the heater core.

Heater puts out lukewarm air now and not cold at least. Going to do another complete engine flush in June and also back-flush the heater core again. Probably still have some clogged tubes in the core.

 

I had to flush my heater core as well as replace the heater control valve. Worked for a while but still had goo in it. I ended up replacing the heater core anyway. No problems since.

 

how do you flush the heater core?

 

Help please

 

You can remove the two hoses for the heater core, and spray a garden hose into the outlet and the other hose is where all gunk will come out, just be careful Ive seen people rupture the heater core by apply too much pressure.

 

Does it matter which hose you spray in

 

The one on top so all the crap goes out the bottom.

 

Thank you!!!!!!!

 

Heater core