heater

[michael holcomb]

my sons truck just blows warm air even after its warmed up. put new thermostat in but no change. any ideas

 

[PanamaExpat]

Check to see if the valve that lets the water pass through the heater core is working properly. If that isn't it you might need to back flush the heater core.

 

[adsm08]

Assuming it is a 91 there shouldn't be a bypass valve.

Check the coolant level, make sure it is full since you have had the system open. Then get the engine good and hot and grab both heater hoses. If one is cooler than the other the core is plugged up.

 

[Jraymer360]

if it's anything like the heater core i just replaced in my truck, it's probably worth it to spend the 20 dollars to get a new one. mine was like rusted clogged up.

 

[kimcrwbr1]

One thing you can try is pull both hoses off the engine going to the heater core and blast it both directions with a garden hose and then blow some air through it to get as much water out as possible then hold both hoses up high and fill it with bleach and let sit overnight. then go ahead and flush it good both ways careful not to get the bleach on your clothes. Oven cleaner also is a good cleaner and if the core springs a leak it was bad anyways.

 

[kimcrwbr1]

Another possibility the door in the duct for the vent is not closing all the way letting cold air into the duct?

 

[michael holcomb]

well im out of ideas, i drove truck 20 miles today and just warm air and temp gauge barely moved

 

[snake]

shoot the upper rad hose with a laser thermometer and see what u have there. If u have 180 or higher it isn't the thermostat, if under, try another maybe higher quality thermostat.

 

[Brownie Mobile]

Well if it means anything my truck rarely ever has time to get the heaters hot, runs nice and cool during the winter takes probaly 45 mins at least to get a reasonable amount of heat going might be the same problem though.

 

[wildbill23c]

Maybe an air bubble in the hoses somewhere causing the warmer coolant not to make it to the heater core. Take the upper heater hose lose from the back of the core start the vehicle and let it warm up completely so the coolant starts flowing if your heater core is plugged there won't be any flow coming out the outlet, if its good coolant will pour out and at the same time it will purge your system of air. Had to do that on my jeep a few years ago.