HVAC Question (Heater Core replacement)

[Bobalos]

Evening Folks,

 

I probably should have posted this up a couple of weeks ago, but it just occured to me.  Im fixin to pull the HVAC box out & replace the heater core & AC core (& replace the dash & fix the EGT gauge), & figured while I had it all out I should check the vacuum pods under there.  I saw from Mikes video that there is one directly on the HVAC box, but I dont know if there are other ones up under the dash (I would suspect there are as there is a bunch of vacuum lines connected together in the middle of the dash).   

 

How do you test them?  apply X amount of vacuum & it should hold that for Y period of time?  or is it enough that if I apply vacuum & it moves through its entire stroke then its good?? 

 

Also, is there a vacuum diagram for this truck?  I looked through my shop manual & could not find one & I figured there would be one under the hood, but there is not...

 

thanks folks.

Bob

 

[Bobalos]

Im having a hard time getting the AC lines apart.  I have the tool to push the spring back,but the lines are not coming apart.  I had the system evacuated & all of the freon removed.  I have double checked & there is no pressure or vacuum in the lines.  its like they are glued in.  I dont want to crank on these things real hard, but............. seems like I have too.

 

These are the tools that Im using......  I also have a few others, but these fit the large AC lines.

 

 

any tips on getting these apart?

 

thanks folks, Im 10 seconds into this project & pissed off............

 

Bob

 

 

 

[Bobalos]

I got them lose, just had to crank on them (harder than I thought I should have had too.........)

 

[dripley]

Same here when I did mine. Really had to work them hard to get them apart.

 

I am pretty sure that all the vacuum lines under the dash connect to the HVAC box, IIRC. I did mine about 4 or 5 years ago and replaced none of the vacuum stuff. It was working then and still is now.

[Bobalos]

When I get it all out, I will draw up a vacuum diagram.  I have just about everything ready to come out, I have to get ready to goto dinner. 

 

When I disconnected the vacuum line @ the firewall by the PCM the hose that goes through the firewall @ the AC lines broke.  kind of looks like it was cracked where it broke.  I wonder if that was not part of my strange ducting behavior...........

 

 

thanks

Bob

 

Edited December 17, 2017 by Bobalos

[Mopar1973Man]

I just push the release tool in twist the two lines and give a light pull. The o ring might be dry and sticky.

[IBMobile]

21 hours ago, Bobalos said:

How do you test them?  apply X amount of vacuum & it should hold that for Y period of time?  or is it enough that if I apply vacuum & it moves through its entire stroke then its good?? 

With a vacuum pump, can be hand pump type, apply up to 15" of vacuum to hose and watch the movement of the lever attached to the vacuum diaphragm.   The vacuum applied to the diaphragm should hold for several minuets if not then there is a leak in the diaphragm.  

 

21 hours ago, Bobalos said:

Also, is there a vacuum diagram for this truck?  I looked through my shop manual & could not find one & I figured there would be one under the hood, but there is not...

                                   See if this will work for you.

 

                                  

[dripley]

1 hour ago, Bobalos said:

 

When I disconnected the vacuum line @ the firewall by the PCM the hose that goes through the firewall @ the AC lines broke.  kind of looks like it was cracked where it broke.  I wonder if that was not part of my strange ducting behavior.........

I wish I had replaced that one when I had mine out. Mine broke later and I dont have much left sticking out of the firewall. My problem was in the blend door and yours might be also.The little plastic coupling cracks and causes problem. Google heater treater. They make a part to replace it with. It is easier to do with the box on the bench than in the truck.

[Tractorman]

I just replaced my heater core about two weeks ago.  I had the HVAC unit on the bench (the only way to do it in my opinion) and spent some time replacing weather stripping around doors and duct connections.  I bought some universal adhesive weather stripping in various sizes for windows at a local hardware store.  In some places where I needed a thin seal, I used the fuzzy side of adhesive Velcro.  Whatever you use, just make sure it has a strong adhesive.

 

I had already done the Heater Treater blend door repair and all vacuum lines and motors were in good condition and passed the vacuum test.  I will be getting the after market cabin filter from Geno's - I definitely recommend it.  My evaporator core had lots of debris blocking air flow. 

 

My windshield and side windows now stay clear and the heater keeps the cab warm on the lowest settings.  Success!

 

- John

Edited December 17, 2017 by Tractorman

[Bobalos]

2 hours ago, dripley said:

I wish I had replaced that one when I had mine out. Mine broke later and I dont have much left sticking out of the firewall. My problem was in the blend door and yours might be also.The little plastic coupling cracks and causes problem. Google heater treater. They make a part to replace it with. It is easier to do with the box on the bench than in the truck.

 

I out the heater treater coupling in a couple of years ago.  I assumed that was what was my heater issue.  It was not.  

 

Thanks

 

1 hour ago, Tractorman said:

I just replaced my heater core about two weeks ago.  I had the HVAC unit on the bench (the only way to do it in my opinion) and spent some time replacing weather stripping around doors and duct connections.  I bought some universal adhesive weather stripping in various sizes for windows at a local hardware store.  In some places where I needed a thin seal, I used the fuzzy side of adhesive Velcro.  Whatever you use, just make sure it has a strong adhesive.

 

I had already done the Heater Treater blend door repair and all vacuum lines and motors were in good condition and passed the vacuum test.  I will be getting the after market cabin filter from Geno's - I definitely recommend it.  My evaporator core had lots of debris blocking air flow. 

 

My windshield and side windows now stay clear and the heater keeps the cab warm on the lowest settings.  Success!

 

- John

I did not know there was a cabin filter retrofit...  I will have to look into that.  Thanks.  

 

I will pull the HVAC box out tomorrow and see what's up.  

 

Thanks. 

[Bobalos]

I have the HVAC box out and the foam seals on the doors and duct joints are all rotten.  Anyone have any luck getting this kind of stuff at the hardware store or auto parts store?  I was thinking maybe a fabric store like Jo Ann's or similar....  

 

Also if hat about this vacuum line??  Is it just plastic tubing?  I would imagine it should be kind of heat resistant as it's right above the turbo and exhaust.  

Also what about this vacuum line??  Is it just plastic tubing?  I would imagine it should be kind of heat resistant as it's right above the turbo and exhaust.  

Edited December 21, 2017 by Bobalos

[Mopar1973Man]

13 minutes ago, Bobalos said:

I have the HVAC box out and the foam seals on the doors and duct joints are all rotten.  Anyone have any luck getting this kind of stuff at the hardware store or auto parts store?

 

Try Home Depot... Weather stripping foam.

 

13 minutes ago, Bobalos said:

Also if hat about this vacuum line??  Is it just plastic tubing?  I would imagine it should be kind of heat resistant as it's right above the turbo and exhaust.

 

Go to NAPA and get 1/8" air brake line. It meets the requirements for that. Just use a small piece of rubber vacuum hose to piece together.

[Bobalos]

Thanks!!

Now if I could only find my vacuum pump..... 

[Dieselfuture]

2 hours ago, Bobalos said:

Thanks!!

Now if I could only find my vacuum pump..... 

It's in line with power steering pump all one unit. First vacuum pump and ps pump bolts to it. Under injection pump. 

[Bobalos]

2 minutes ago, Dieselfuture said:

It's in line with power steering pump all one unit. First vacuum pump and ps pump bolts to it. Under injection pump. 

I was talking about my hand held vacuum pump to test these vacuum pods. 

 

I'm know where that one is, I just replaced it and dammit was that expensive.....  Lol.  

 

I think I have everything I need now.  I can't find anything to replace the seal that goes around the heater core and evap tubes...  It's a semi soft rubber sheet.  I might have something at work that might work.  

 

Thanks Bob

 

 

[Mopar1973Man]

On a previous job, I used the same weather stripping tape just wrapped around the tubes to fill the void. Something that is wide but not overly thick. 

[Bobalos]

I think the blend door is sticking.  I hooked it up last night & when I go from hot to cold it only moves about 1/16th of a revolution.  I seem to recall that it should move 1/3rd.  Im going to take the motor off tonight (assuming its not raining again) & see if I cant figure out whats going on.  

 

Any ideas or suggestions would be appreciated.  

 

Bob

[Mopar1973Man]

Any updates to this if you got the blend door working?

[BBHD]

Have you checked the set screw on the heater treater coupling? I found out the PO had already installed one in my truck and the set screw had backed out a little and wasn't allowing full swing of my blend door.