Bought a POS conversion van / motor home, '98 B3500. Currently has multiple issues with the main (van) HVAC system. I am pretty familiar with other Chrysler products of this era, Jeeps, trucks etc but I've never had a van so "packaging" will be different. And one issue I have is the van is currently about two hours away from me so I can't just run outside and look.

Basically, every function doesn't work properly so I'm either trying to come up with a game plan for repair, or maybe search for a common link between all the problems.

Issues:
- Blower only blows on high. This is the resistor, I know.

- Pretty sure the evap box is full of leaves and pine needles. Can you get this apart to clean it out or no?

- No real selectability between vents. So, what will happen is if I put it on the dash vents, the dash vents don't blow. The def/floor vents do seem to work. When I switch the **** between settings SOMETHING happens, but it rarely seems to be the right thing, and it doesn't seem to always do the same thing wrong, if you know what I mean. I know with a similar issue in a Grand CHerokee, the blend doors were electrically actuated and plastic so they break. You had to disassemble the entire interior, seats, column, everything to pull the HVAC unit out and replace the doors. Of course because this was a 3 days job you were also doing the heater core and evap. I feel like I'm looking at the same issue here, but I figured I'd check - are these doors electric or vacuum? Because if they're vacuum I might just have a vac leak I can smoke out to try and fix this without tearing the whole interior out. Also, unfamiliar with the internal design - is it possible for the leaves and pine needles to make their way through the system and block the doors maybe? The dude I bought it from gave me a new control panel and was like, "here this will fix it in ten minutes", to which I replied, "my friend, you know nothing about cars, and you'd better cut your asking price in half for me to do this god damn job". Which he did. Surprisingly.

- HVAC blows HOT when A/C is selected. Again, maybe a blend door issue? I know some designs have the heater core and evap core "constantly open" and they use a blend door to mix the air to meet temperature. Again maybe one single source issue for all these problems? I didn't think to check if the compressor was running and now the van is a few hours away at a shop so....

Is these a tutorial anywhere that describes the process and maybe tips/tricks for pulling the entire HVAC assembly out from behind the dash, if I do have to get into blend doors and actuators? Or, maybe it's actually serviceable without going through all that?

Any thoughts?

Thanks guys!

 

pretty sure it's blend doors problem

 

Blend doors, vent actuators, and water to heater core are vacuum controlled on these vans. Sounds like you've got a vacuum leak. If you fix that, it will likely take care of all the issues you described (except the blower motor resistor, of course).

It's basically impossible to get the evap box open, since one of the screws is completely inaccessible. You might be able to remove all the screws you can reach, and then bend the top of the box up enough to look down inside and see if there's trash inside.

Another (much easier) option is to remove the blower motor and clean out the bottom of the box through that hole. I found an old wasp nest attached to my blower fan. Turned out it sounded awful because of the nest, and there was nothing wrong with the actual motor.

Good luck, these vacuum leaks are a pain.