Where did my heat go??

[AlexZ71]

Ok guys ive been having a huge issue with my truck and have checked every forum out there. I have a 94 chevy k1500 z71 with a 6 in suspension lift and 3in body on 35's. its got the 5.7L 350. so one day my heat just seemed to stop. i had heat on the way to the store and when i came back out and started my truck up, the heat was gone. i have replaced my thermostat and am confident its a 195 degree but it shows on my dash that my truck runs around 150degrees, i flushed the heater core with water and air, then i knew i had a garbage radiator (cracked, lots of bars leak in it) so i went ahead and replaced the radiator hoping then id get my heat back. Still no luck. i have also noticed the radiator hose from the radiator to the motor is hot but the hose from the block and back to the radiator is not nearly as hot. ive burped the system and still nothing. any ideas??? really cant handle these illinois winters without heat!!

Alex

 

[towman]

i would verify the engine temp just because it is a new thermostat doesn't mean it is good, a few years ago i went thru three t stats before i got a good one, a lot of off shore junk
parts on the market anymore

 

[Old Goat Ninja]

I had an old Jeep where that happened to me as well. Tried everything. Couldn't figure it out. Weeks went by. Dead of winter with a soft top. Gawd it sucked. Turned out it was..... a fuse

So I'm going to guess a fuse.

 

[great white]

Ok guys ive been having a huge issue with my truck and have checked every forum out there. I have a 94 chevy k1500 z71 with a 6 in suspension lift and 3in body on 35's. its got the 5.7L 350. so one day my heat just seemed to stop. i had heat on the way to the store and when i came back out and started my truck up, the heat was gone. i have replaced my thermostat and am confident its a 195 degree but it shows on my dash that my truck runs around 150degrees, i flushed the heater core with water and air, then i knew i had a garbage radiator (cracked, lots of bars leak in it) so i went ahead and replaced the radiator hoping then id get my heat back. Still no luck. i have also noticed the radiator hose from the radiator to the motor is hot but the hose from the block and back to the radiator is not nearly as hot. ive burped the system and still nothing. any ideas??? really cant handle these illinois winters without heat!!

Alex

"Bars leaks"

Uh oh....really bad stuff for heater cores.

Bars leaks tends to accumulate in heater cores in my experience and clogs them up.

If it's hot going to the core and cold coming out you have no flow.

I would suspect clogging.

Sorry, no really easy fix for that one.

You need to figure out why the hot coolant isn't circulating but i know where i'd put my bet....

 

[jp97K1500]

I agree with Great White's post if your engine is operating at correct temp. (about 190-200degrees) check heater inlet hoses on fire wall. If only one is hot (about same temp. as upper radiator hose) then you know you have no flow through your heater core and you need to replace it. You can try back flushing it but if you had bars leak in it I can almost bet it needs to be replaced. If both hoses are hot though you could have your temperature blend door problem. Also it is normal for your lower radiator hose to be cooler than your top hose because this is the return hose that flows cooled coolant back to your engine after the radiator has cooled it down. Hope this helps.

 

[AlexZ71]

Appreciate the answers guys. heres where im at now. still no heat. checked hoses coming off heater core. both are hot. all hoses feel as though they are at the proper temp. as my truck warms up i will watch my gauge get to right about 200 degrees then ill see the thermostat open and temp go down. itll go down to about 130 in cold weather. not sure why my temp wont stay up... as far as in the cab goes, air flow is good and strong except on recirculation. when i put it on max, i lose jsut about all airflow through vents? at this point im thinking about checking or just replacing actuator motor with the thought that when i turn the temp from hot to cold the air does get colder but when i go back to hot i have no heat although its maybe a few degrees warmer than when set on cold. kinda thinking the actuator motor or blend door is sticking and not letting heat through?? any thoughts?? thanks so much guys truly appreciate it

 

[great white]

I'll still bet most of the heater core is plugged with bars leaks. Wouldn't Be the first time I've seen that.

Only way to tell is open the heater box and feel the core.

The actuators are an easy check. Get up under the dash and watch the levers swing as you change selections.

An internally broken blend door is a different story....