Hello all. Got myself a 2000 Expy and it's perfect exceeeeeeeppppttttt......

The heater has issues. I doubt it's part of the coolant system. Since owning the vehicle (2 years), I've flushed the radiator twice, and never had had an overheating issue. Nor do I notice leaks anywhere under the dash.

Here is an actual description of the problem. A/C works perfect. But then I go to put the heat on and the air is not hot. However, when I step on the gas, it gets hot. Once I take my foot off the gas though, to stop for a red light let's say, and the cold air comes back.

It's pretty much the same story with the rear heat.

So is this a vacuum issue, or something more sinister?

On a side note, it's not the digital control system, it's the regular turn **** control style system.

Oh, and one more, smaller, issue. No one, and I mean no one seems to be able to even tell me where to start looking. It's the horn. It doesn't work. Let me rephrase that. It doesn't work if the key is on. Neither does the steering wheel buttons like cruise.

However, the horn works if the truck is off. The only reason I know this is the horn makes noise is due to the remote door lock and alarm. It works when I lock the doors and set the alarm with the remote.

There are two reasons I'm bent about this. One is you really need a horn in case someone is going to back into you into a parking lot, or something to that effect. And two, I want to install a train horn

Thanks in advance.

 

On your horn and cruse control issues, did you check your fuses ? Your heater could be a bad blend door, or you haven't got all the air out of your cooling system.

 

Both of the heater cores are restricted. You said you flushed the radiator twice, but you didn't say you flushed both heater cores. At this point there could be 10 years of deposits clogging the bottom half of both cores.

The horn and steering wheel buttons not working are the result of a worn out clockspring at the base of the steering wheel. The door locks and alarm directly operate the horn relay and do not utilize any of the wiring that passes through the clockspring. That's why the horn works for the door chirp and alarm.

 

Wow. Seriously, even mechanics just looked at me and shrugged over the horn thing. I don't suppose you'd know the best way for me to fix it?

As far as the heater cores, how would I flush them?

Thanks again!

 

Yeah, change the clockspring.
RockAuto Parts Catalog
After you click the above link wait a few seconds for the page to load then click the INFO button and there will be a couple of videos.

The absolute best way is to remove the two hoses going to it and then run a garden hose through it full blast, in both directions.

 

You're the ****ing man! I'll be doing both of these this weekend. Will report back. Thanks!!!

 

Hmmmm, OK, I need a little more direction. I see two hoses going into the firewall by the back of the engine, and they have T splitters in them with the hoses running down parralell to the firewall.

Are these the hoses that go to the heater core? Also, How do I disconnect them at that T junction? Are they threaded or do I just pull them off?

Oh, and do I have to flush the entire system while I'm doing this? I just did it two months ago. I don't have a problem re-flushing it, it's easy, but it'd be easier to just flush the heater core hehe

Example pic:

 

The two lines that T off going down the firewall are the lines that also supply the rear heater coil. What I did when I did mine was to add flush fittings to the supply and return lines of the front coil on the firewall side of the T's you mentioned. Then I bought these clamps (shown here) 3 Piece Line Clamp Set which allowed me to clamp off the rest of the system and exclusively flush the core itself. You'll have to buy a couple of sets of these in order to have enough of the right size. I don't think you're able to take the T's apart, but I didn't mess with them myself. Flushing the core worked for a short period but it seemed to plug up again not long after, I ended up replacing the core itself which was a real pain in the a$$ and took 10 hours to do, and of course I had to do it in the middle of winter. If you get to that point let me know, I have some pretty good instructions I can e-mail you.

 

Well, success. I cut one of the hoses going into the firewall and installed a t-line and I flushed the **** out of it. Ended up doing the entire system again. Heat blows hot now.

Problem is, I must have did something to the PCV valve. I noticed a loud hissing noise and when I wiggled the PCV valve it got better and worse depending on how I wiggled it.

So I went to Auto Zone and bought a new PCV valve but it didn't help. It hisses a little less but it still does it. If I pull it towards the front of the engine compartment it stops hissing.

Can anyone tell me how I fix this?

Thanks!

 

I just finished replacing my front heater core. The pcv valve was doing the same thing. I replaced it and it doing fine now. I think my rear heater core needs to be replaced though. Rear heat is just luke warm. Pulled the panel off and the supply line to rear heater core is hot but the return line is barely warm. May try to flush just that core.

 

OK, grrr, I just got done replacing the pcv and the groumet that it plugs into. So I guess it's the hose that attaches to the pvc.

Is that correct? Is it hard to replace. It looks....tight....in that area. To say the least.