erratic heat in cab

Khoover1988 said:

heres the proab im having, but first heres what ive done:

coolant flush, heater core flush, new thermostat, properly burped system of air.



before i did this i had no heat in the truck, now i have heat, but only when motor is reved up (like highway driving, or revving in driveway). when the truck idles i slowly loose heat, and defrost blows just cold.



my doors/air flap diverters are working fine, i can hear them going full back and forth.



WTH is going on? its starting to get really cold here now...ugh...

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Khoover1988 said:

heres the proab im having, but first heres what ive done:
coolant flush, heater core flush, new thermostat, properly burped system of air.

before i did this i had no heat in the truck, now i have heat, but only when motor is reved up (like highway driving, or revving in driveway). when the truck idles i slowly loose heat, and defrost blows just cold.

my doors/air flap diverters are working fine, i can hear them going full back and forth.

WTH is going on? its starting to get really cold here now...ugh...

Click to expand...

Khoover1988 said:

oh yea, itll freeze your *** outa the cab. is there such thing as a heater core getting weak? i get warm air, when i flushed the core nasty **** came out, water flow was good through it, but could there be just too much calcium buildup and crap inside that its just effecting heat transfur?

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KyleW2 said:

Mines opposite. When I'm idling or coasting at a speed I get damn good heat but when I'm accelerating kinda heavily, it switches to defrost.
I know my heater core is bad though. I just deal with the smell lol


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WATER PUMP FAILURES

Sometimes a water pump will fail internally due to severe corrosion wearing away the impeller blades, or the impeller comes loose on the shaft, or the shaft itself may break from metal fatigue (caused by flexing due to an out-of-balance fan).

Many late model vehicles (Chrysler in particular) have plastic impellers to improve cooling efficiency and to reduce cavitation (drag). But the plastic can wear down quickly if the coolant is dirty and contains abrasives. The pump may not leak, but it may not circulate enough coolant through the engine to keep the engine at normal operating temperature.

One way to test for a bad water pump is to squeeze the upper radiator hose when the engine is hot and idling. Careful, because the hose will be HOT! If you do not feel much coolant circulating through the hose when you rev the engine, the pump may be bad. The other cause might be a bad thermostat that is not opening properly (remove and inspect the thermostat), or a clogged radiator.

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