Hey Guys,

Bare with me here as I try and explain my situation... but for starters, my truck seems to take a really long time to get heat going in the cab (like to the point where I think my powerstroke diesel warms up faster) as well as a coolant temperature suitable for forced hot air heating.

This has been continuing issue from last year. I've really only had this truck 2 years now and the first season I had it I barely drove it in the winter.


This time last year I pulled the heater core. Flushed it internally, cleaned the already clean coils (where the air flows past) and removed any debris that might have made it way into the HVAC system (leaves, pine needles, etc...). I also had the blower motor out and did the same there. The air conditioning evap. coil was clean on the visible side (the side you can see when you pull the blower motor) and the blower motor appears to be working fine in all speeds.

When I use the A/C in the summer (or vent but in re-circ mode) there seems to be significant air flow through the vents. A little less airflow comes through when the actual "vent" selection is made. (recirc versus fresh air). As far as I have ever seen this is 100% normal.

The moment you slide the temp control from cold to hot the air flow seems to decrease significantly. The temp control moves freely.

Is this "normal" for this particular HVAC system? I mean aside from coolant temp which i'll address next, what else could be contributing to poor heat in the cab? I mean its mainly an airflow issue... Any thoughts? Vacuum motors appear to be working fine. There are no know/visual vacuum leaks either.


Now as far as the coolant temp goes, the other night it was in the low 30* temps around here. Leaving my friends house I drove about a mile on a rural road and then hit the highway. Jumped on the highway and was running about 60/65 mph at around 2500 rpm. My mileage on the highway was roughly 5 miles. By time I got off the highway and onto the other rural road I take home, the coolant temp was just barely over 100*f

Now before you say thermostat...I JUST put a brand new 195* t-stat in a month ago. Prior to that the thermostat I removed was only a year old as well and a 195. I had the new one so figured just replace it... I also had the same kind of issue with the coolant last year. I'm just determined to get heat and quickly in this truck this year! Any thoughts on how to heat the engine quicker? My first and most obvious thought is that since this is a factory A/C truck AND a 4x4, the cooling system is probably much larger.

The cooling system is full, i've bled it out and I am pretty sure the heater core is bled of air as well... shy of using a piece of clear pipe to be certain of course.

Any thoughts where I could start to get this thing warmer faster? I am open to all crazy ideas!!! I'm a plumber (for the most part) so trying to re-route something doesn't scare me. Just the cost of the project does. ha-ha

One crazy idea I had was to maybe pull the mech. fan and replace it with an electric one. This way I could regulate when the fan pulls air through the radiator. Speaking of fans, I also don't think my fan is the problem but if you have a thought on this i'm all ears...

or... another crazy idea i had was to somehow throttle the coolant into the heater core from a different point off the water pump ? maybe re-route something just for the winter?

Sorry for the long-winded post. I'm just sick of being cold... To any older gents out there, does getting cold quicker and being miserable have any direct relation with age? I swear I am continually colder as each year goes by...


Thanks for any suggestions,

 

You could have a radiator the size of a football field, it wouldn't matter.
The thermostat is a variable restriction to keep the coolant leaving the engine (and heater loop) at a constant temperature.
If the radiator is over cooling the thermostat should just restrict the flow some more until the engine is able to heat what coolant gets by is at 195*

People don't get it.
It is not an on/off switch.
It modulates flow.
It should not allow the engine to run too cool.

If your truck is running at 100* the thermostat will never open.
BUT coolant will continue to flow through the heater loop.
If you see any flow in your radiator with the cap off, your thermostat is stuck open.

You're a plumber, so you understand how a tempering valve or anti-scald shower body works.

 

Oh I absolutely get it...(well sort of, I obviously had some doubt or I wouldn't have inquired LOL). that's why I'm banging my head against the wall as to why the cab isn't heating.

Correct me if I'm wrong here but the water pump does still pump some water through the block but through the smaller ports (i.e. the bypass hose thats part of the t-stat housing) so just as you said it's not really pushing through the radiator until the stat opens up and allows for the coolant to push through the upper hose.

On a total side note, and this is something I have been meaning to tackle for a while but am going to try and get to this weekend, could too far advanced timing create a cooler water temp? OK it sounds a little silly but it was just a thought... however in warmer months (i.e. summer) the water temp manages to jump up to it's operating temp rather quick.

I'm just trying to go through all my options at this point. I don't think it's a simple solution like the thermostat being stuck open. I could only be so lucky.

thanks!!!

 

Too much lead (advance) will cause detonation, and overheating.

Take the cap off and start the truck.
Look for coolant flowing in the radiator. (it shouldn't be)

If it is, your thermostat is letting it by.

The various bypass hoses should only allow water to circulate within the engine or heater loop, not through the radiator.

 

ok, that's exactly what I thought. I know for certain the t-stat is staying closed. I drained the cooling system 3 weeks ago in order to change out my timing cover gasket and when I filled it back up I did just that. Let the engine warm up until the t-stat opened, yadda yadda yadda.

Interesting point on the timing advance causing detonation and overheating... I do not have either condition! Franklin2 noted that the balance could have slipped and timing may be on just showing an advanced timing because of the slip. Again, something I just have to poke around with...hopefully today sometime!

Thanks!

 

Well, if the thermostat opened when the engine warmed I would say your gauge is no good.

Are the two heater hoses getting hot before the thermostat opens?

 

I will get back to you on the hose question. I am almost certain those hoses are too hot to handle before the stat opens but I'm not 100%. I'll go fire her up and take a look-see. I haven't run the truck today so it's been dead cold since yesterday afternoon.

I'll also have to check on that temp gauge. It's an aftermarket gauge with the sensor installed into the intake manifold. Maybe I should move that sensor or mount another gauge onto the heater hose side so I can monitor heater core coolant temp. ha-ha I have one of those infrared thermometers. I'll do a comparison... not sure how accurate they are either but if the infrared thermometer is comparable to the gauge then I can probably rule out a bad gauge....

OK all good places to start beyond the simple stuff!

 

Point the non-contact IR thermometer at the outlet of the thermostat housing.
It should be very close to the thermostat rating.

If both heater hoses are hot then the heater core is flowing.
If your truck is still blowing cold air you need to look at the doors in the ductwork.

 

EDIT: ok, I'm a bonehead... I just found this link from the FAQ section (after posting my inquiry below).
https://www.ford-trucks.com/forums/1...cs-needed.html
I'll thumb though this first but in the meantime if anyone has other input I'm still on board for suggestions. -Thanks



It's been a while but I finally found some time to come back to this topic...

I found that the engine temp is fine. The heater hoses heat just fine. Using an IR thermometer the heater hoses reached 140*f pretty quickly (maybe 5 minutes? I forget at this point) but more importantly they got hot and in a timely fashion.

SO this leads me to believe there is a problem with my ductwork/venting. Just for fun I pulled the blower fan. Found a few leaves & needles but nothing significant. I also pulled off the ac core cover. Nothing blocking the way.

After trying to get some heat in the truck yesterday I switched the selector to vent. Temp was on cold and I got a blast of cold air. I noticed though when I switch to Hot the air flow is almost cut down to nothing. I think this may be the culprit.

Anyone have extensive experience with the innards of the HVAC or are there links/pics avail? I don't know where to begin without tearing the dash apart. There eventually is heat but if feels like something is blocking the airflow when in Hot mode.

Thoughts???

Thanks so Much!

 

Here's some pictures. I wonder if your temp blend door is stuck.

 

Maybe the door has come off its hinge?
Maybe the back of the heater core is also packed with debris?
Maybe the core itself is covered in corrosion and restricting the airflow?

I think I would pick a warm day and pull the core to look at what I can.

 

Dave, Thanks for posting. This is awesome. I think you're onto something with the temp door sticking. Hopefully if I can find some time this weekend or during the holiday I can take a better look.

The core was my first thought too. I pulled it last year and it was perfectly clear. Internally and externally. I wish the problem was as simple as that ha-ha. I'll "third" the door issue.

This weekend is suppose to be comfortable around here. But of course I need to be on a job with the truck...Just my luck.

Thanks again for the input.