Heater issues

[6speedsd]

I assume this is a good place for this. Temps are starting to drop here at night. Been cool enough to run the heat early mornings. Anyways earlier this week truck started not blowing good hot air. It would blow kinda warm but not as hot as it should be. After doing some google searching I found that the blend door tends to be an issue in these trucks. But from what I can see if that breaks you don't get any heat at all. I am getting some heat most of the time. I call it luke warm. It's always like that in th morning when you need it the most. Sometimes I can cut the heat off, then turn it back on after 20 mins or so and it's blowing as hot ad it should. Was thinking maybe the valve in the heater hose was stuck shut or something. It moves freely in and out by hand. Tonight I went out and fooled with that valve some. It stays open all the time no matter whether the heat is on or off. I assume open anyways. The lever is out (towards the firewall). I pulled the vacuum line off but can't feel a vacuum like I should be able to. Vacuum pump is working. I'm confused here. I don't know what else to check. I figure if the heater core was clogged or on the fritz I wouldn't get heat at all. Just seems weird that sometimes it works great then others it blows semi warm air.

Any ideas or things to check? Cold weather is coming before too long and I need good heat!

 

[6.0 p-stroke]

When you're accelerating or under constant throttle does it get hot, then cool off when you coast? You probably just need to add coolant, so it has more warm fluid to circulate.

 

[suprdzlduty]

is the truck warmed up all the way? or does it the heater temp go up and down no matter how long you drive it? do you have the auto climate control or dial type controls?

 

[6speedsd]

Coolant level is full. This may be a dumb question but would it matter if I didn't have a good 50/50 mix? Like if I have more water than antifreeze. I wouldn't think that would matter. Hot water or hot antifreeze should still produce hot air, right?

Auto climate controls. It's gets warm after the truck is up to normal temps like its supposed to. Just usually not as warm as it should be. Temp doesn't seem to change no matter if I'm idling, coasting, or accelerating.

This morning it blew good and warm. If I push the cold button to lower the temp, it does drop as it should, and then when I push the hot button the temps raise. Just seems off that sometimes it works great then others it doesn't get warm like it should it never just blows cold air, well not after coolant temps are up anyways.

 

[6.0 p-stroke]

It shouldn't matter what fluid is in there, it'll still get hot.
Maybe your thermostat is bad, so it never allows the coolant to fully heat up.

 

[HOOV3R]

Does it start blowing heat when rpms are increased? I had an issue with mine a few weeks ago, where I didn't have heat at idle. Closed my valves for my coolant filter half way, and it works just like it used to.

 

[6speedsd]

It doesn't get any hotter or cooler with different rpms. Like I said it doesn't matter if you are idling or under throttle, it still blows the same temp.

Coolant gets up to normal op temps. Around 190 after its warmed up. Why I didn't think t-stat would be acting up. I guess that would be a cheap thing to replace anyways just to see. As far as I know the t-stat thats in there now could be the original one from the factory. The more I go over this truck the more I realize the previous owner didn't take very good care of it.

 

[Atsah]

I would change out the T-stat and see what happens.. It sounds like it is working somewhat..

 

[Gary]

Your heater core is probably pluged up, and also your engine oil cooler. I have had people tell that after I changed their engine oil cooler the heater worked much better ( and they didn't think they had a heat problem). Now I have flushed out MANY heater core (cars & trucks) with CLR to fix a low to no heat problem. You can disconect the hoses going to the heater core, then use a couple of short lenghts of 5/8 hose and pour CLR in the core and let it sit for 45 minutes, then flush it out, and then hook everything back up and try it. I would also check your coolant and oil temp deltas and see if the engine oil cooler is plugged.

 

[6speedsd]

Oil cooler is only 2 mths old. I replaced that 2 weeks after I bought the truck. Temps are right where they should be with eot and ect so I know that's not the issue.

If the core was clogged, why would it work great sometimes then not so good at others? I'd figure if it was clogged I wouldn't get any heat at all, which isn't the case.

 

[Atsah]

You mention that your coolant may not be 50/50.. Could be your T-stat has some rust on it.. I would start there, cheap enough..

 

[6speedsd]

I went and got a new one today. Will get it put in tomorrow and see what happens.

 

[Big Angry Hillbilly]

Does your truck have a vacuum actuated coolant shut off valve in one of the heater hoses?

 

[6speedsd]

Yes. Read some of my earlier posts on this thread and you'll see where I talked about it.

Not trying to sound like a smartass, just don't want to type it all out again.

 

[6speedsd]

Ok new T-stat is in. No help. Still blows just warm enough to knock the chill off. But now, it seems to blow colder when you are coasting or idling. Going down the road at speed it's warmer. I don't get it.

 

[Atsah]

Two things that will cause this you can check..


1.)
The metal pipe that the heater hose hooks onto. The one that curves around the alternator and goes down to the timing cover near the water pump. Remove the pipe, and check to make sure the end of the pipe is not clogged with rust or other crud. I have seen them, with a rust chunk stuck in the end of the pipe, and cause no heat at idle.

2.)
The temperature blend door motor actuator is located behind the glove box. It is on top of the heater box. There is a square in a circle that is the end of the shaft. You can watch this as you turn it from hot to cold to see if it moves. I have also seen a few times, the door inside the heater box break off the shaft where the actuator motor turns it. This allows the blend door to move around at will. If you remove the actuator, you can turn the door by hand from the spot where the actuator fits to check the door. This is most likey the issue..

Your not getting any residue around the bottle correct?

 

[6speedsd]

Residue as in puking? Not one single bit. Truck doesn't use a drop of coolant.

That's the thing though. I get SOME heat at idle. I get SOME heat throughout the whole driving range. It's not like it's just blowing cold air. Like I said, I call it Luke warm heat. It's just warm enough to knock the chill off most of the time. Then other times I can shut the heat off, leave it off for 20 mins, turn it back on and it's blowing toasty warm! This at first made me think it was the blend door. But I can alternate from the highest heat setting to the lowest cold setting and the temps change accordingly. And instantly. I guess if the blend door wasn't closing/opening fully it would cause it to not get toasty warm like it should.

 

[6speedsd]

So what would cause the temp to change with rpms/speed? If I'm going down the road at speed, say 65 mph, it's blowing good and warm. But as soon as you stop at a light or something, it immediately cools off. Not cold, but a definite drop in warmth.

 

[HOOV3R]

So what would cause the temp to change with rpms/speed? If I'm going down the road at speed, say 65 mph, it's blowing good and warm. But as soon as you stop at a light or something, it immediately cools off. Not cold, but a definite drop in warmth.

Lack of flow. Fins broken off of the water pump, or a plugged heater core.

 

[6speedsd]

I've been wondering about the heater core. I wouldn't think it's water pump related. Truck had never ran over the 190's on coolant temp, even when it was 105 degrees outside, towing my trailer with the AC on max.