Low Temperature Heater Output

[pistonslap]

I have a 2000 4X4 5.3 pick-up that does not put out high enough temp on the heater. The blower puts out plenty of air. The temperature control knob is moving something when i adjust it.(I can hear it clearly.) The motor temperature is close to the factory recommended normal. I cleaned the factory cabin air filters. The coolant looks pristine because as it was a city truck. Any suggestions as what to check first? Thanks in advance!

[txab]

Check to make sure your system is full

Check heater core to make sure it's not plugged

[pistonslap]

Check to make sure your system is full

Check heater core to make sure it's not plugged

I guess the only way to check the heater core is to pull it out. Or try a cooling system flush. Maybe ill take the cabin filters out again with the engine warm and feel how hot the heater core gets. If the water is circulating properly it should get hot one would think.

[txab]

You can remove the hoses going to/from the core and flush water through them. Be sure your blend door is actually moving. When you say the temp is "close to normal", what is it? Does it it get to about 200?

[ken1mod]

Had a Ford that did this once. I restored better heat by reverse flushing the heater core. Lotsa crap came out and the heat got better. This was in Washington on the way to Alaska in October.

 

Ken

[pistonslap]

A short update, I purged the cooling system as recommended in my manual.I never noticed any air in the system but it is warmer now. Not hot hot, but warmer. The motor temperature gets close to what the cab manual says it should.It is in Celsius degrees and I don't recall off hand the temp . One thing I've noticed is the engine takes a long time to heat up. I'll wait a bit and see how it handles the colder weather. If it is not hot enough ill flush the heater core and change the thermostat.

[oldschool327]

Older trucks could develop a problem with the heater valve not opening all the way letting full flow of coolant through. Check too see if the valve is good to go.

[Doug_Scott]

A short update, I purged the cooling system as recommended in my manual.I never noticed any air in the system but it is warmer now. Not hot hot, but warmer. The motor temperature gets close to what the cab manual says it should.It is in Celsius degrees and I don't recall off hand the temp . One thing I've noticed is the engine takes a long time to heat up. I'll wait a bit and see how it handles the colder weather. If it is not hot enough ill flush the heater core and change the thermostat.

 

Generally speaking, if the engine takes a long time to warm up, the thermostat is stuck open.

 

And if you have poor heat, you tend to run the fan at a higher speed, and lets face it, the heater core is really nothing more than a small auxiliary radiator, so you are actually making it take even longer to warm up by running the heater fan at a high speed....