2nd Gen Non-Engine/Transmission Replacing heater core what else while there

[FCrowder]

I have a 99 qc that the heater core started leaking. I'm going to replace it and the evap while im in there. What else should i replace while i do this? Thanks for any advice. Francis

 

[RHestand]

I just replaced my htr. core and evap. recently due to a evap. leak. Somehow leaves got in there and caused corrosion.
The only thing I would add is to thoroughly inspect the plastic blend doors and vac. hoses for cracks. Mine were still good, but it's not unusual for them to break or leak.
Ray

 

[griggsd]

A new dash board may fit the bill during this project; they're easily damaged in on-off cycle to get to the area. Geno's has them. I didn't when replacing my heater core 2 yrs ago, now I have all the resultant dash cracks covered with a dash-mat instead.

 

[Glen Pratt]

Definitely change the evaporator while you're in there. -Glen

 

[Matt42]

I have a 99 qc that the heater core started leaking. I'm going to replace it and the evap while im in there. What else should i replace while i do this? Thanks for any advice. Francis

Francis: Where are you located? If there's a TDR member nearby who has done that, you might be able to get some local help. How-some-ever, here's my fifty cents worth, having done so myself.



-My heater core is what failed, and it developed a pinhole leak. I think it was caused by a poor electrical ground from the core to chassis, causing electrolysis. (The ground wire was loose. ) I made double-certain sure that all metal parts of the new core were firmly and securely grounded.

-I suggest that you use a core that has flexibly mounted tubes. That will make it much easier to hook up the heater hoses in the engine bay. Trust me on this.

-As others have suggested, this is the time to also replace the AC evaporator. Spend the extra $$ and use a MoPar evaporator. DO NOT try to do this on the cheap. You will be sorry. Do not ask how I know this.

-VERY IMPORTANT!! There are five plastic clips that snap into the steel firewall just under the windshield. These clips receive the sheet metal screws that hold the dashboard in. Buy exact replacements from the dealer (or AuVeeCo if they have them) and replace all five. Hold your nose and spend the money. If you don't do this, the dashboard will rattle and squeak and drive you and your passengers completely insane. The clips may look OK, but they will not be OK.

-Lubricate the pivot points on the air blend door, if you don't replace the assembly. I suggest that you make up a paste of lock cylinder graphite and molybdenum ("moly") disulfide anti-seize compound. Lightly paint it onto the pivot points with a Q-Tip.

-Check all of the under-dash vacuum hoses. If they are cracked, replace them now.

-Have a look at the location of where the heater core and AC evaporator will be in relation to the black plastic cover. Consider drilling -neat- 1/4 inch holes using a brad point bit at the top of the housing, and then snapping in a cap. That will allow you to later use a foaming cleaner to get rid of mildew and bad smells. I didn't do that and I wish I had. Drilling after installation means I have to stand on my head and risk puncturing something expensive.

-Lubricate the mechanical parts that operate the under-dash stuff. I suggest Lubriplate, or a paste of lubriplate and anti-seize. In the southwestern heat, I use a peculiar synthetic oil called Snake Oil. It stands up to the heat really well.

-Consider painting the under-dash areas that rust, if that sort of thing bothers you.

-Check all of the wires that ground to locations under the dash. Check the clutch pedal area to make sure that you don't have a hydraulic fluid leak. (If your truck is a manual. )

-When you reinstall the heater hoses, I suggest re-using the spring-clamps that were installed at the factory. I ruined one, and I have never been able to get a stainless worm-drive clamp to work right.

-When you take the A/C evaporator off, follow the discharge instructions carefully. It has to be discharged slowly, not with a big boom or a roaring hiss. Check inevitable drips of oil for black specks. Those are an indication that you may need a new $10 orifice or a new compressor. Now is the time to take care if the problem, if you can. I needed both, which I was able to do myself at big savings.

-Replace the accumulator. You need to take it 3/4 of the way off anyway, and any time you open up the A/C system, you should replace it anyway. This outfit Automotive Air Conditioning Parts & Equipment - www.ACKITS. COM can help you. They are local to me, and they have never, ever steered me wrong.



Bottom line: You have done a Good Thing by asking what else ought to be done when you open up the system. You can save yourself a boatload of trouble later. Questions? Just ask. There's a world of experience here. And not everybody will agree with me.

 

[FCrowder]

I had the dash off about 18 months ago to replace the top. wish i had done heater and evap then. already have got new oem heater core $200 and evap $180. started taking apart today. will finish during the week.



Thanks for all the advice!!!

Francis