JH7406

I have a 98 Cherokee, 6 cyl, 107k miles. For some time the heater has only blown luke warm air. Flushed the cooling system, replaced the tstat but didn't help. Flushed the heater core twice now (inlet and outlet). Checked that the temp control swith was working (could feel the solenoid shaft move when I adjusted the temp). Also get cold air when cold selected.

Saw something on the internet about blend doors. Could this be my problem? How can I check?

Also, is it possible that I have a weak water pump. Temp guage reads normal (about 185-190 I think). Noticed that the heater hoses don't get hot.

Would appreciate any suggestions.

djb383

Both heater hoses should be very hot, if not, suspect a coolant flow problem. How old is the water pump?

JH7406

Pretty sute the water pump is original.

athenscj5

If by flushed the coolant system you mean drained and filled and drained again and maybe pushed some water through it I would try using air to force water backwards through the heater core by way of the heater hoses before I spent any real money on it. You'll be suprised at how much the air will get out of the heater core.

JH7406

I'm confident I got the core flushed. Both directions. blew the water out with compressed air. Opened the flush tee cap (that I installed to flush the coolant system) to help remove after refilling the cooling system and running the engine for a while. Don't think it's because of air in the system.

Bassfishertim2015

I have an 89. Heater didn't blow warm air what so ever. So I decided to flush the core. I let simple green sit in the core for about 15 min. Then I filled it up with water over and over and over and blew it out with compressed air. Back flushed and forward flushed. All in all took about 3 hours. Best 3 hours of my life. Heater works better then my moms new Chevy cobalt