No heat! This sucks!

[Coletrain523]

So I have a 2001 dodge ram 1500 5.9 4x4 and I have no heat. Well the air is barely warm. The truck has coolant, gets up to temp and all. But still nothing. You guys have some ideas I can check off the list? Thanks

 

[MADDOG]

Sounds like the infamous HVAC system blend door failure. Pretty common failure

 

[Coletrain523]

Well I didnt want to hear that lol. But it might be since everything else checks out. But I looked under the dash at that price and when I turn from heat to cold it turns? So the door should be working correct?

 

[Coletrain523]

So I checked the blend door. I took off the actuator and manually turned the door and can move it and hear the door hit the sides and all. But still no heat? So what else could I check?

 

[viperguy]

I have same problem on my 03. I'm thinking heating core needs to be flushed.

 

[Wahrsuul]

Not sure about the Ram, but my 01 Dakota had this issue. you have to back-flush the heater core. meaning figure out which hose is coming _from_ the engine, then disconnect both hoses from the heater core and use a garden hose to pump water through in the opposite direction.

 

[Coletrain523]

Well when I changed the radiator a few months ago it was flushed out, so I havent thought of it. But I did take the temp gun to it when it's at operating temp and one hose is about pretty steady 160-170 and the other is pretty erratic and I've seen it be 120-130. Then I can laser it again and it be 140-150 and then back to the 130's. So it' not far behind the other hose. But is that enough of a difference to mean no heat?

 

[dudeman2009]

Flushing the heater core in a 17 year old truck with the original heater core is asking for a leak that will fog up the windows and make the cab smell like coolant. Do not flush the heater core unless you are willing to replace it. Instead, take a measure of the upper radiator hose, thats the best case for heater temp, comparing that to the heater hoses will give you a rough indication to the amount of flow through the heater core. Another option is to separate the heater hose on the passenger side of the engine and see how much flow there is, then separate the passenger side and do the same, the flow should be very close to each other.

Coolant color and composition when you last changed it will also give you a good indication as to heater core health. And if you had to replace the radiator because it was leaking or clogged, there is a pretty good chance the heater core is in the same condition, as its just a smaller radiator.

 

[Jeepwalker]

Back flushing with a garden hose should be ok on your heater core. It's not that much pressure. If it goes, then it just saved you a failure a month from now. In some circumstances it makes a big difference but in others makes little to no difference at all. I'd also check if there's an outside air damper that's not closing. Even though you might think it's heating, an outside air damper (above the pass footwell) ...if there is one, can negate any heat the system can put out. Not sure if your tk has one. On our jeep, the outside air door hinges broke (common fault). Replacing is a lot of work and it was cold so I just carefully repositioned it in place with a long screwdriver and took a stiff piece of bent wire (with nail-sharp ends) and inserted it in place to hold the door against it's hole. That was an easy no-heat fix done years ago.

Also feel the heater hoses. If they're not hot then you have a blockage or valve issue or water pump issue. A bad headgasket can also cause a no heat issue ..even if it hasn't let go yet. If you hear gurgling in the mornings, then it could be a headgasket failure in the works. They can last years in this state before they give out. Like others said, it could be core blockage too. If the heater hoses are hot then I'd look at other parts of the system. 160 isn't all that hot but enough to produce weak heat. My car's thermostat flaked out and the car was only getting 160 deg according to my snap on scan tool ..and it wasn't throwing much heat at that. Now it's up to 195 again and heats nicely!

 

[dapepper9]

You can also try putting the fan on max ac lol. Recirculates and reheats the air in the cab so it gets pretty damn warm lol

 

[Wahrsuul]

If you have no heat, then replacing the core should already be an option unless it's a blend door issue. Either way, it's not a simple job.

 

[dudeman2009]

Back flushing with a garden hose should be ok on your heater core. It's not that much pressure. If it goes, then it just saved you a failure a month from now.

It's not so much about the pressure, as you're right, it should not be able to blow a hole in it. But it can flush out dirt/debris that is clogging a hole. Without the flush the hole may stay clogged for years, it may not. I've flushed several with a hose on a light stream, and every time there was no leaks, only poor heat prior, then after within a week they were leaking. I recommend against it completely unless the heater core is newer or you plan on replacing it anyway.

 

[Wahrsuul]

It's possible you might flush out dirt that clogging a hole, but if it's also clogging the core and keeping the heat from working, then it needs to be replaced in either case. Flushing is the way to find out.

 

[pmk138]

I am having the same problem. My HVAC controls seem to work fine. I got very little heat. I have verified that the heat/cold knob does cause the blend door motor to spin, However I am wondering if the blend door motor is weak. I have timed the amount of time it takes the blend door motor to spin from one direction to the other and it is about 12 seconds each way. I really don't hear any noise like a door closing. I figured it is either the blend door motor or heater core. Does anybody have any other thoughts? It looks like it is a pain to remove the blend door motor assembly, but much easier that disassembling the the dash. I did take a video of the motor spinning, but the file is too big to attach.

 

[Wahrsuul]

Its a PITA to do either, no doubt. Not sure how long it should take the door to move, and I've never really heard a noise when it does. The openings usually have a foam or rubber gasket so you wouldn't likely hear it closing.

 

[Coletrain523]

Well I'm pretty sure my blend door is good I've manually moved it and it seems good. But even before I had the radiator replaced (started leaking around the seam) the coolant has always been in good condition always green no gunk or anything. So I'm not sure I want to flush considering it might do more harm than good, or it might be the best Idk. But I feel like it could be something else since it was good up until it just stopped heating. At least thats how it felt.

 

[dudeman2009]

The blend door motor makes the very slightest noise when moving, no idea how long it takes as ive never timed it, but its got to be perfectly quiet to hear, engine and blower off.

 

[EvilSpirit]

I just reverse flushed the heater core in my 96 Ram and it made a world of difference. Luckily I have access to a local high school auto shop which has HOT water available through the garden hose outlet. I clamped both the hoses shut on the engine side, then installed flushing tees in both hoses. Starting on the drivers side (this is reverse flow) I ran hot water through the core about 15-20 mins then switched to the other side for about the same time. Went back and did both ways again about 10 mins each. Let the water drain out, installed the caps, ran engine and topped off system. BIG difference in heat - it is now uncomfortable to hold your hand in front of heat ducts on high fan. I should mention that the previous owner always ran a 205* stat in the truck. Now if I could just get the engine to warm up quicker! Blocking off part of the rad has had no effect - still takes several miles to start blowing heat.

I used to have a "kit" made just for flushing heater cores. 5 gallon pail with an intercooler pump set up with hose connections to hook up to flushing tees. I'd put 3-4 gallons of a 50-50 mix of hot water and white vinegar and reverse flush the core for about an hour. Had pretty good results. I need to get that back from a long term loan to a friend.

Another buddy says he switches the hoses every year on his trucks so the cores "reverse flush" themselves. Has done this every year on his 98 Durango and many other vehicles and swears by it. Might start trying that myself. On a core like the 2nd gens where both connections go in the top and there is no water flow valve, I don't see why it would matter which is the inlet.

 

[dudeman2009]

Another buddy says he switches the hoses every year on his trucks so the cores "reverse flush" themselves. Has done this every year on his 98 Durango and many other vehicles and swears by it. Might start trying that myself. On a core like the 2nd gens where both connections go in the top and there is no water flow valve, I don't see why it would matter which is the inlet.

Thats an interesting idea. I don't see the harm as long as the heater core is in good condition and there isn't large particulate circulating in the coolant. I'll have to give that one a try.

Now if I could just get the engine to warm up quicker! Blocking off part of the rad has had no effect - still takes several miles to start blowing heat.

Yeah, the rather large blocks by today's standards take forever to heat up, especially since they are cast iron not aluminium, unlike just about any Chevy engine since 03-04. Thats one of the things I love about the trailblazer, it can be 5 degrees out and my truck takes 20 miles to get to operating temp, but that little I6 gets there with blistering heat in just 2 miles. I've found nothing gets these trucks to warm up fast, I stuck a 195 from the 180 that was in there and didn't notice too much, though that was in the summer, so I wasn't checking. I might take it up to that 205 mark if I can find one for it.

 

[Coletrain523]

So I've given it more time and it still has no heat so no change there sadly. But now I've noticed that my system is cutting on and off. Like it's fine when I'm just cruising or sitting still but as soon as I give it gas it stops blowing in general. Then when I let off it starts again? Sometimes it pops when I let off but not all the time. What the heck is happening?