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Heat Not Working

R

reg44reg

NAXJA Forum User
Location
Westminster, CO
Winter is here and I'm just now realizing my heat isn't working so well. General question - when using defrost, is the secondary cooling fan kicking on every 10 seconds normal? Seems unnecessary considering its running at normal temps, plus it tends to drop the engine temp a few degrees.

This only happens when using defrost, main vent or floor settings it never happens. As for no heat, what would be the first things to check?

99 Cherokee Sport 4.0l
 
Yes it's normal in my experience for the secondary electronic fan to do this when the ac Is on. Be it for defrost or just regular ac. It will even do this when the engine is cold.

If your head is lacking or non existant and running temps are normal then you likely need to flush your heater core.

Has the coolant been changed regularly? Always green?

Brown coolant means gunk in your system

Sent from my SM-G950U using Tapatalk
 
Yeah, I had the thermostat changed last year and I've checked the coolant since. Still
I'll try back flushing the core to see if that fixes the problem, looks easy enough to do.
Thanks
 
I did the ol' back flush end of summer. I went back and forth flushing so many times I filled a 5 gallon bucket with water. Unbelievable sludge. It had probably never been done.



Heat works great now.
 
I used plain old fashioned water. Anyone add anything else to the list of chems when simply backflushing a core? Might help him get more gunk out

Sent from my SM-G950U using Tapatalk
 
reg44reg said:
Winter is here and I'm just now realizing my heat isn't working so well. General question - when using defrost, is the secondary cooling fan kicking on every 10 seconds normal? Seems unnecessary considering its running at normal temps, plus it tends to drop the engine temp a few degrees.

This only happens when using defrost, main vent or floor settings it never happens. As for no heat, what would be the first things to check?

99 Cherokee Sport 4.0l
Click to expand...


This is normal A/C runs in defrost mode to dehumidify the air. The second fan comes on whenever the a/c runs.
 
Someone on another thread mentioned it may also be the door that allows air to blow over the heater core. May also want to investigate this option

Sent from my SM-G950U using Tapatalk
 
Thanks alexgalexg - Your video was one of the first watched when I researched back flushing. I'm guessing this door is embedded within the box that houses the cores?
 
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