Hi All,  Got in the truck to get the Christmas tree we are having our first good storm of the year in Northern CA.  So we drove with no defrost and foggy windows.  Reading the trouble shooting options the hoses are both Hot with the right being hotter,  no hot air blowing anywhere  If you turned off the fans and idled I did feel some heat but not enough to warm the cab.  Looking at  a trip to Seattle at Xmas time this isn't going to cut it. 

 

Is the Heater Treater still the hot ticket for this issue?

 

Thanks Cold in the Central Valley!!

Michael

Edited December 2, 20195 yr by int3man
Typo's

The HVAC box really isn't bad to pull, and it will be worth it because everything will be easier to work on.  

O.K.  So I taught the kid about Series and Parallel batteries.  I asked if they had a carbon pile tester, to test under a load and they looked at me like I had 2 heads.  Next time I'm taking my hand held Snap On Heater (Battery load tester) and BLOW their minds!!

 

So looking at the heater hoses I get it now the heater core is active 24/7 I thought that it was like my normal Mopars and there was a heater control valve but there is not.  So I think that my heater core is plugged and possibly the air inlet.  When I go on MAX with the AC the wind will blow you out of the truck when I go defrost you can feel a movement of air but it is cold.  So if the water is not circulating in the core, then I am blowing outside air against he windshield, that is why it is cool to the feel.  So Back flush and forward flush it is.  Anyone know the hose diameter?

 

Thanks

Michael :- )

There is a very good chance the heater core is blocked by debris in the HVAC box since there is no filter blocking the debris from enetering thru the cowl. You also seem to have poor air flow. We have seen many instances of that here. When you grab the heater hoses are both of them hot? If the inlet and outlet are both hot, the water is circulating thru the core.

 

Pretty sure the heater hose is 5/8".

Yes Sir both hoses are hot!  Doesn't the AC use the same air for cooling.  It can't because the Heater core is hot all the time.  HMM are there separate fresh air inlets for A.C. and Heat?  No it would cost too much.

 

HMM

Michael: - )

1 hour ago, int3man said:

Yes Sir both hoses are hot!  Doesn't the AC use the same air for cooling.  It can't because the Heater core is hot all the time.  HMM are there separate fresh air inlets for A.C. and Heat?  No it would cost too much.

 

HMM

Michael: - )

Thats what the blend door is for. Exactly how it does it is a bit beyond me. Others could explain it much better. In the articles section under 2nd gen 24v, cab interior there is an article on removing the case with some photos of the HVAC box split open that might help. Sorry but my tablet will not let me link it.

 

Sounds like your problem is in the hvac box and not internal to the heater core. But flushing is easy to try.

40 minutes ago, dripley said:

Thats what the blend door is for. Exactly how it does it is a bit beyond me. Others could explain it much better. In the articles section under 2nd gen 24v, cab interior there is an article on removing the case with some photos of the HVAC box split open that might help. Sorry but my tablet will not let me link it.

 

Sounds like your problem is in the hvac box and not internal to the heater core. But flushing is easy to try.

O.K.  Found the post to the HVAC removed.

 

The Heater Runs 24 / 7 weither it allows air to flow over it is the job of the Blend door it controls the air flow from the fan.  The recirculation door is vacuum operated.  And it looked like the Evaporator was the dirt filter.  So HUMM  I think I'm back to flushing it.

 

Michael : - )

@Mopar1973Man has a good write up in there too on just removing the box without taking the whole interior apart. Thats what I used when I replaced the dash pad and rebuilt the the box.  Nothing wrong with the one you found just a good bit more involved.

O.K.  Bought some hoses and fittings and back flushed.  Got a piece of something out of the inlet when I back flushed it.  Looked like a leaf or a piece of foil seal that you cut out of a antifreeze container, I didn't capture it.  So I took the truck for a drive and low and behold we have Heat.  Not blasting out the defrost vents but the face vents are blowing warm / hot air, and at hot higher volume.  So I am going to wire tie off the recirculation door so that it stays in the recirculation mode.  I can remove the 2 nuts and slide down the actuator and tie it off actuated.

 

Thanks for the assist!!

Michael :- )

You can pull blower motor off and get a lot of junk out away from heater core, if you're flexible you can use a rubber hose on a vacuum cleaner and suck it clean for the most part. I had good luck doing it, but of course had to take dash apart not long after to change heater core as it developed a tiny pin hole at the bottom and I was smelling antifreeze. Maybe junk at bottom is what was keeping it from leaking. 

1 hour ago, Dieselfuture said:

You can pull blower motor off and get a lot of junk out away from heater core,

 

If my memory serves correct, and that is a big if, I think you were cleaning the junk away from the evaporator core since the evaporator core is the next item in the path downstream from the blower box.  All of the air passes through the evaporator core and then through the blend door, and then the heater core.  I don't think the heater core is accessible for cleaning unless the whole HVAC assembly is removed. 

 

You can flog me if I'm wrong..

 

- John

8 hours ago, Tractorman said:

 

If my memory serves correct, and that is a big if, I think you were cleaning the junk away from the evaporator core since the evaporator core is the next item in the path downstream from the blower box.  All of the air passes through the evaporator core and then through the blend door, and then the heater core.  I don't think the heater core is accessible for cleaning unless the whole HVAC assembly is removed. 

 

You can flog me if I'm wrong..

 

- John

Honestly I don't know what I was cleaning, I just know it had some junk there blocking air flow and coincidentally the heater core started to leak shortly after. 

Well I was out in the front yard today and found the foil that came out, when I back flushed the heater core.  At least it was this color that flashed by in the clear hose.

 

So the P.O. didn't do a good job of policing his trash.

Michael :- )

On ‎12‎/‎19‎/‎2019 at 9:37 PM, int3man said:

So I am going to wire tie off the recirculation door so that it stays in the recirculation mode.

 

Since you live in a moderate climate, you can probably get away with that. Once you get into moist conditions in below freezing weather, the AC will operate considerably less often and you will probably see windows begin to fog in the cab.  You need outside air to keep windows clear.

 

If that yellow piece did come from your heater core, that would certainly restrict the flow.  So, hope all is well now.

 

- John

51 minutes ago, Tractorman said:

 

Since you live in a moderate climate, you can probably get away with that. Once you get into moist conditions in below freezing weather, the AC will operate considerably less often and you will probably see windows begin to fog in the cab.  You need outside air to keep windows clear.

 

If that yellow piece did come from your heater core, that would certainly restrict the flow.  So, hope all is well now.

 

- John

Huh I thought that the AC ran in Defrost mode to dehumidify the air.  At least the Cadillacs were that way.

 

Michael :- )

54 minutes ago, int3man said:

Huh I thought that the AC ran in Defrost mode to dehumidify the air. 

 

Your are correct.  But, defrost mode brings in outside air.  Any significant moisture from the outside is removed in the evaporator core with the AC running.  The dry air then flows across the windshield and mixes with the air inside the cab picking up any moisture available (wet clothes, moisture from breathing passengers, etc.) and then exits the cab via one-way vents usually located in an inconspicuous area.  So, there always fresh, dry air flowing across the windshield.

 

On ‎12‎/‎19‎/‎2019 at 9:37 PM, int3man said:

So I am going to wire tie off the recirculation door so that it stays in the recirculation mode. 

 

Recirc mode just continues to recirculate all of the air inside the cab over and over again.  None of the air exits the cab and no fresh air enters the cab.  Any moisture that is picked up in the cab can only be removed if the AC is operating and  the outside temperature is well above freezing.  Once the outside air temperature falls below freezing the AC will operate less frequently so the water that is condensed from air passing through the evaporator core will not freeze and block the air flow.  The result is that the air in the cab will slowly become saturated with moisture and at some point can and probably will start condensing on the windows.

 

Once the outside temperature gets well below freezing, it really doesn't matter if the AC doesn't cycle at all when in the defrost mode.  Example:  outside air temperature is 20 degrees and it is foggy.  Even that air that is fully saturated (100% humidity) will be very dry by the time it is heated to at least 120 degrees and reaches the windshield.   The air will whisk away any moisture an then leave the cab through the one-way vents.

 

- John