Well, I finally got around to changing out my leaking heater core yesterday. I will tell you, if you can find someone that will replace it cheap do it. It has got to be one of the most annoying things to do in the truck. I am really beginning to think that when they built my truck they hung the heater core by a string and then built the truck around it.

Things that I learned from doing this:

1) Dashes in the newer truck, at least the 1994 2wd that I have, are different than the ones in the older 89-90 trucks. There are several things such as the dash support bracket behind the stereo, along with almost every other dash part that I tried to swap over. After about 3 hours of modifying, cutting and bending I finally got the 1994 stereo braketry to work in my 1990 pickup. I did this only because where my stereo was was tore up because the guy that owned the truck before me didn't know how to properly install a radio.

2) Sunpro supertach IIs (mini) fit perfectly in the ac vent to the left of the steering wheel. Pics to come, I'm at school and don't have them here.

3) Taking your time and doing things right, especially with dash parts, pays off in the long run.

4) If you can when replacing the heater core replace the fan also, hit two birds with one stone.

5) I was lucky and could just swap the plastic box that holds the heater core with the box from my 2wd pickup. If you can go this route it will be a whole heck of alot easier. I pulled the leaking heater core out of my old one to make sure it was what was leaking and lets just say it wasn't very easy.

Any questions or someone want some tips let me know I'd be glad to help. I started on the heater core at about 1pm yesterday, got delayed and had to take a break for about 4 hours, was battling a hang over in the process, and fabricated all the pieces for the dash and ended up getting done at 11:30pm. Its not that hard of a job just a royal PITA.

 

6) Do your back a favor and just take out the shotgun seat instead of trying to bend around it.

 

I didn't do that just because I'm lazy. Plus it gave me a place to sit while I was working on the dash parts. It would have made it easier on me cause the hanging upside down with feet hanging over the top of the seat with a hangover didn't help <-- didn't do that though.

Tach Mounting:

I took pics to do a write up incase anyone wants me to.

 

Hi, just wondering if in all your heater/dash work you learned how the temp control knob works. I recently did some work on my stereo and when I was done the temp control knob on the dash would only turn about half way. It was like I dropped something down into the gears turning inside the mysterious white box. After poking around for a while I finally just turned the thing (a little too hard) and heard a plastic breaking sound. It's turning fine now. But the problem is the temperature doesn't change at all.

The thing is though, I traced the cable connected to the knob and it's still moving fine. It goes through the firewall to a junction of tubes just under the windshield. Like I said, that all seems to be working fine. Do you know if there's something electrical or otherwise that that knob also does to allow air to flow through the selected vents? I'm only getting cool air right now.

Any advice you can offer will help, I'm fresh out of ideas short of buying a new control box (that can't be cheap!).

Greg

 

If I remember right there are two cables connected to the temperature control. One opens and closes a flap that either lets air move through the heater core or move through the a/c and bypasses the heater core. The other one, as you said, goes through the firewall and out to that junction.

The one that you didn't check is connected to the bottom of the box that contains the heatercore. You should be able to access it near the vent that blows onto the floor on the right of it. I'll check today if it ever stops raining and get back to ya. (EDIT: I'm willing to bet thats the plastic breaking sound that you heard. The flap is controlled by a plastic lever. )

I'm willing to be that is the problem, the flap that needs to open to let air pass through the heatercore. Correct me if any of this is wrong, I am trying to work from memory since I did it all without a manual.

 

Dang, I'll bet that has to be it. Thanks a lot! I'll dig into it later this weekend.

Appreciate the reply!

 

No problem, If you have any other problems don't hesitate to ask.