hey all, my girlfriends 98 dakota barely has any heat. both of the heater hoses in the bay are hot, so the core is getting heat to it(might do a backflush for the heck of it), but when you turn on the fan, it blows warmish for 2 seconds, then its back to cool. im not sure what to do/check next. in another post someone recommended:
inspect blower fan and resistor operation, as well as blend door

the blower fan is working, i assume, because, well.. there is air being blown through the vents... but resistor operation? blend door?

no idea how to go about checking those. id love to surprise her by fixing her heat for winter. any writeups, or instructions oh how to check whatever it is i should check next would be sweet.

thanks!

 

Back flush it then see how it works

 

will do. but i was told that if both hoses were hot, backflushing wouldnt matter. might help a little, but not that much.

when i get the kit, which hose should i connect to? they both go through the firewall just to the right of the engine(driver-side), one goes to the front along the driver-side of the engine, and the other goes behind the engine and comes to the front via the passenger side.

this is on a 5.2. it will save me having to sit there while her car warms up feeling which hose warms up first

when i did my jeep, i backflushed the whole system. i dont really want to do the whole system, and would rather just do the heater core. i was thinking about getting a backflush kit, but also cutting the intake heater core hose and letting the fluid flush through there. then just get a barbed fitting and some hose clamps to close that side up.

 

just flush both ways to be sure is all

A Vid that may help he uses compressed air but just use your garden hose and water.

I also don't recommend the chemicals he used

 

ok thanks, yeah, ive seen that video. im going to try that tonight. if it doesnt work, what do i check next, and how?

one thing ive never been sure of... so after the flushing, how do i know how much water is left in the core? unless i blow it out like he did, there is going to be a decent amount of water left in the core, so i should add extra un mixed antifreeze... but how much?

 

I had this problem in my '97 3.9l. My problem was the water pumps fins had rusted away. I too had both hot heater hoses... pro mechanic told me the hoses were being gravity fed from the bottom, which made sense because, like yours, my heat would be hot for a minute, then get cold again.

I think i still have the old water pump in my garage somewhere... ill try to find it and throw you a picture of what im talking about.

 

The amount of water that may get stuck would be minimal and you wouldn't need to worry about it. If you live in extremely cold climates and normally do a 60/40 split then add a little more coolant.

Just make sure you burp your system well. I've found that you need to jack up the front end while burping the cooling system in these trucks because air will get stuck in the heater core. Your goal is to make the rad cap the highest point so air will exit while you're running the truck.

Good luck

 

Here it is

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And it's useless...



ForumRunner_20131108_112649.jpg


Check to make sure you're not just holding air in the HC like he said... if that's not the case i would do this test... drain the coolant and refill with straight water, then run the engine with the heat on full blast for 5-10 minutes after the tstat opens... then drain the water. Save some of the water you drained. Then start backflushing the heater core... save some of that water in a different container. If the water from the heater core looks significantly more contaminated than the rest of the water... the water is not moving through the heater core (which you really pretty much already know...).

Fill the system back up with straight water again and warm it up... if that doesn't get your heat working, then you probably have the problem with the water pump you see in the pictures.

Hope this helps... did this all last year and it is what got me interested in vehicle maintenance :-)

 

backflushing worked wonders. takes forever to get warm, but at least it does. i actually used compressed air to blow all the water out, then filled the heater core with coolant mix, reattached hoses. minimal burping required. thanks for your advice and help!