NO HEAT!!!
 

Hey guys I need some help. I have a 96 grand cherokee and I can't figure out how to get heat. I've changed the thermostat, the heat control unit, I've flushed the heater core and listened for the hot and cold valve to open and close ( which it does). The fan works fine but all I seem to get is slightly warmish air. Any help would be appreciated!

Did you bleed all the air from the system? Does the coolant temp rise and fall? I use this https://www.amazon.com/Lisle-24680-S.../dp/B00A6AS6LY whenever I do cooling system work. You lock that funnel on and fill the radiator until the funnel has coolant in it as well. Let it run with the heat on full hot and high and you'll start to see air bubbles come out and fluid drop in to replace it. Just keep that funnel full until no more air bubbles. I make sure to squeeze all the hoses to help along any air bubbles. Never fails me. It ensures a properly bled system. Literally just used it over the weekend when replacing a radiator. Took no time at all to bleed the system once it reached operating temperature. One of the "must have" DIY'er tools IMO

What do you mean by bleeding the system ?....also no coolant temp stays right at 210 when it's all warmed up...just took it on a 4 hour drive and it was solid I froze my ass off but it was solid

Ok I'll give it a shot

if both heater hoses are hot it means water is going thru the heater. if air is cold heat is not being transfered from the core. plugged? doors,heat controls not working right. my 98 needed help opening one door. follow the control cable or look up the motor actuator. someone last week fixed his by looking under the dash,pass side.? where is post?!! it was bad motor year? dont know.
search.

AMAZON and EBAY sells the same funnel set for about 10 bucks less. I just bought one.

Good info. I was just posting it up for an example :cheers:

Well I'm thinking the core is plugged like you guys thought!....I'll let you know after I replace it

how did you flush it then?

I think all the little fins in the core are clogged...the water will still flow through it but the sediments in between the fins isn't allowing them to get hot from the water..so no heat or just warm air

not quite how a heater core works. If hot water flows through it, you'll get heat. If the passageway is blocked then no heat.


https://cimg2.ibsrv.net/gimg/www.che...44129861d0.jpg

I just though of something. The fins may be plugged with tree seeds and other debris cutting down the airflow. The problem where I live is pine needles. They get into everything including my house! IDK if there's an easy way to get to it to clean it either. Vacuum maybe?

The passage way for the water is not blocked. When I flushed it I had clear water flowing through both ways. If the fins are clogged up the fan can't blow across them to push that hot air through the cab.....right?....so my thinking is in order to get heat I need to either clean the fins or put a new core

Right! You might want to check the cowl area under the wiper motor cover. It may have collected some debris also. Something else to check. Make sure the hose from the thermostat goes to the bottom pipe of the heater core. That way any air will bleed out thru the water pump naturally. Most heater cores are built like lasagna noodles with thin passages between them. Air can get trapped as tiny bubbles in between, mostly near the top, cutting down on heat transfer.

Man, if you're going to go as far as going through the necessary work to clean the thing, might as well toss a new one in.