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Evaporator core and heater core

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Old 07-19-2021, 07:56 AM
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Default Evaporator core and heater core

I recently purchased an ‘87 Dakota. I’m completely new to working on my car however I can follow directions pretty well (especially with pictures and videos). I haven’t seen any on my ‘87 Dakota that shows how to replace the evaporator core. While I’m in the box I’d like to just replace all the parts, they are 34 years old and not working well. Does anyone have any videos or pictures of the process to get the box out of the truck so I can replace these? Thank you
 
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Old 07-19-2021, 04:21 PM
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You're in luck!

The boxes didn't change worth mentioning from 1987 to 1996 (around 1990 they added a sensor in the evap coils, and dropped the vacuum tubing to activate the heater control valve - which shuts the heater off on recirculate, so not a big deal).

I say that because both the 1995 and the 1996 factory service manuals are here available for download.

It has drawings, which can do for the pictures.

And you're right, I'd replace ALL of that, including the blower motor, while it's open.

Oh, wait, I DID replace all that last time I was in.

I used some blue 1/8" silicon vacuum hose to replace that old brittle hard line into the engine bay; I used a pair of Adel clamps to hold them in place also.

I don't have many pictures of that, though ... since I was working from the FSM for my 1988. (Hint: Bishko shows it still in stock paper and disc for a 1987; paper i$ expen$ive for my ta$te$, but the disc is handy especially if you have a PDF viewer that lets you notate)

But a quick overview -

Remove the heater hoses inside the engine bay.

Get the A/C evacuated or recovered by a proper machine if there's any R12 or R134a still in it (R12 factory, R134a if it's been worked on.)

Plan on new A/C lines while you're doing, BTW ... and if they're factory, get them remade at a proper hose shop (we have several in town where I live).

Might want to clean, prime, and paint them before you take them to the hose shop ...

Remove the radio.

Carefully remove the heater or HVAC control unit (be careful! The tab holding that cable for the temperature control is brittle. I had to use zip ties because the tab broke on mine.)

Remove the lower half dash which includes the glove box.

Remove the plenum that feeds the driver's and passenger's vents.

Under the hood, remove the four 1/4-20 nuts (7/16" or 1/2", I forget which) that hold the HVAC box in place.

Pull it into the cab, and rotate it slightly to drop it down.

WHILE it's apart, also replace all the weatherstripping and seals with generic weatherstripping. I had to build up the big one on the plenum (you'll recognize what I mean).

Carefully split the box - you'll have to pop out all the clips and remove all the screws. Also, carefully remove the clips that hold the pivot shafts in place. Plus, you'll have to remove the recirc valve (passenger side, by the blower motor). Do note which color hose goes where; take LOTS of color pictures.

While the box is open, I'd carefully lubricate all the pivot points

Also, be sure to weatherstrip AROUND both the heater core and the evaporator to keep air from leaking.

Reverse to re-assemble.

If in doubt when taking apart, take pictures. Even if you're sure, take pictures

RwP
 
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Old 07-20-2021, 05:57 AM
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Originally Posted by RalphP
You're in luck!

The boxes didn't change worth mentioning from 1987 to 1996 (around 1990 they added a sensor in the evap coils, and dropped the vacuum tubing to activate the heater control valve - which shuts the heater off on recirculate, so not a big deal).

I say that because both the 1995 and the 1996 factory service manuals are here available for download.

It has drawings, which can do for the pictures.

And you're right, I'd replace ALL of that, including the blower motor, while it's open.

Oh, wait, I DID replace all that last time I was in.

I used some blue 1/8" silicon vacuum hose to replace that old brittle hard line into the engine bay; I used a pair of Adel clamps to hold them in place also.

I don't have many pictures of that, though ... since I was working from the FSM for my 1988. (Hint: Bishko shows it still in stock paper and disc for a 1987; paper i$ expen$ive for my ta$te$, but the disc is handy especially if you have a PDF viewer that lets you notate)

But a quick overview -

Remove the heater hoses inside the engine bay.

Get the A/C evacuated or recovered by a proper machine if there's any R12 or R134a still in it (R12 factory, R134a if it's been worked on.)

Plan on new A/C lines while you're doing, BTW ... and if they're factory, get them remade at a proper hose shop (we have several in town where I live).

Might want to clean, prime, and paint them before you take them to the hose shop ...

Remove the radio.

Carefully remove the heater or HVAC control unit (be careful! The tab holding that cable for the temperature control is brittle. I had to use zip ties because the tab broke on mine.)

Remove the lower half dash which includes the glove box.

Remove the plenum that feeds the driver's and passenger's vents.

Under the hood, remove the four 1/4-20 nuts (7/16" or 1/2", I forget which) that hold the HVAC box in place.

Pull it into the cab, and rotate it slightly to drop it down.

WHILE it's apart, also replace all the weatherstripping and seals with generic weatherstripping. I had to build up the big one on the plenum (you'll recognize what I mean).

Carefully split the box - you'll have to pop out all the clips and remove all the screws. Also, carefully remove the clips that hold the pivot shafts in place. Plus, you'll have to remove the recirc valve (passenger side, by the blower motor). Do note which color hose goes where; take LOTS of color pictures.

While the box is open, I'd carefully lubricate all the pivot points

Also, be sure to weatherstrip AROUND both the heater core and the evaporator to keep air from leaking.

Reverse to re-assemble.

If in doubt when taking apart, take pictures. Even if you're sure, take pictures

RwP
I will try and find those manuals for the ‘95 and ‘96. Many thanks for the hands on experience too and sharing that with me. How long would you say it would take a first timer to complete this?
 
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Old 07-20-2021, 09:55 AM
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Took me about a day working; but I had preordered everything I thought I'd need, and had another set of wheels to pick up the weatherstripping at the local Big Box Store. (Home Depot and Lowe's for me here.)

RwP
 
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Old 07-20-2021, 01:04 PM
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Ralph, you were able to get the box out without dropping the steering column down and freeing up the entire dash? I have had the heater box on my 95 5.2 out twice. I rebuilt the box just as you did. I thought I needed the dash completely free in order to get the box out.
 
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Old 07-20-2021, 09:35 PM
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Originally Posted by Flounderguy
Ralph, you were able to get the box out without dropping the steering column down and freeing up the entire dash? I have had the heater box on my 95 5.2 out twice. I rebuilt the box just as you did. I thought I needed the dash completely free in order to get the box out.
I may have dropped the column, but no, just the lower dash, as specified in the factory service manual.

RwP
 



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